Draft version January 22, 2021 Typeset using LATEX default style in AASTeX63

Massive White Dwarfs in Young Star Clusters

Harvey B. Richer ,1 Ilaria Caiazzo ,2 Helen Du,1 Steffani Grondin,1 James Hegarty,1 Jeremy Heyl ,1 Ronan Kerr,3 David R. Miller1 And Sarah Thiele1 —

1University of British Columbia Vancouver, BC, Canada 2California Institute of Technology Pasadena, Ca, USA 3University of Texas at Austin Austin, Texas, USA

(Received December 4, 2020; Revised January 6, 2021; Accepted January 15, 2021) Submitted to The Astrophysical Journal

ABSTRACT We have carried out a search for massive white dwarfs (WDs) in the direction of young open star clusters using the Gaia DR2 database. The aim of this survey was to provide robust data for new and previously known high-mass WDs regarding cluster membership, to highlight WDs previously included in the Initial Final Mass Relation (IFMR) that are unlikely members of their respective clusters according to Gaia astrometry and to select an unequivocal WD sample that could then be compared with the host clusters’ turnoff masses. All promising WD candidates in each cluster CMD were followed up with spectroscopy from Gemini in order to determine whether they were indeed WDs and derive their masses, temperatures and ages. In order to be considered cluster members, white dwarfs were required to have proper motions and parallaxes within 2, 3, or 4-σ of that of their potential parent cluster based on how contaminated the field was in their region of the sky, have a cooling age that was less than the cluster age and a mass that was broadly consistent with the IFMR. A number of WDs included in current versions of the IFMR turned out to be non-members and a number of apparent members, based on Gaia’s astrometric data alone, were rejected as their mass and/or cooling times were incompatible with cluster membership. In this way, we developed a highly selected IFMR sample for high mass WDs that, surprisingly, contained no precursor masses significantly in excess of ∼6 M .

Keywords: stars: clusters – massive – supernovae – white dwarfs – Galaxy: open clusters

1. INTRODUCTION arXiv:2101.08300v1 [astro-ph.SR] 20 Jan 2021 The maximum mass of a star that is capable of forming a WD is an important astrophysical quantity. It controls the SN II rate, the rate of formation of neutron stars and black holes and the chemical enrichment and star formation rate of galaxies. If the maximum mass is in fact lower than previously thought, the number of supernova explosions would be higher, as would the number of neutron stars and black holes formed. Additionally, the amount of heavy elements pumped back into the interstellar medium would increase along with the dust production and likely the star formation rate in a galaxy. A related quantity is the maximum possible mass of a WD, whose upper limit from theoretical considerations is thought to be 1.38 M (Nomoto 1987). However, presently, there are no WDs known with

Corresponding author: Harvey B. Richer [email protected] 2 Richer et al.

Gaia parallaxes for which we can say with a high degree of confidence that they have evolved via single star evolution that approach this limit. Single star evolution implies that in any phase of its life the star was not involved in mass transfer from another star or in a merger. The current record-holder for the most massive WD thought to be the product of single-star evolution is GD 50, at 1.28 M . Historically associated with the Pleiades, recent Gaia analysis seems to indicate that GD 50 is not associated with any star cluster but appears to be a member of the 150 Myr old AB Doradus moving group (Gagn´eet al. 2018). If GD 50 is excluded from the formal IFMR because of its uncertain origin (which makes it difficult to establish its precursor’s mass) and the possibility that it may indeed be a merger remnant (Vennes et al. 1996), the most massive single-evolution WD in a star cluster with a well-determined Gaia parallax currently known becomes the Pleiades WD LB1497 at 1.05 M , whose precursor was 5.86 M (Cummings et al. 2018). This WD is well below the Chandrasekhar mass, and therefore the current sample does not come close to testing this upper limit. It is the goal of our current survey to try and locate more massive single-source WDs. On a related issue, there appears to be some discrepancy in the rate of supernovae explosions from massive stars. The current upper main sequence mass limit for WD production is thought to be about 8 M (Weidemann & Koester 1983); however, Horiuchi et al.(2011) have shown that, if every star above 8 M becomes a core-collapse SN II, the predicted rate for type II supernovae would be roughly double the observed rate. One way to resolve this problem would be if the lower mass limit for supernova production were significantly higher: about a 12 M lower limit to stars exploding as SN II would be needed for a Kroupa IMF (Kroupa & Weidner 2003) to bring the prediction in line with observations. We would then expect to see WDs that evolved from main sequence stars as massive as 12 M . At present, no WDs are known with progenitors anywhere near as massive as this, but it is not at all clear whether searches carried out thus far would have been sensitive to these massive WDs, as their high masses would have resulted in small WD radii and hence low luminosities. Additionally, this would have required examining star clusters as young as 20 Myrs for possible WD members, a search that has not been done systematically. In this survey paper, we remain agnostic about the mass limit for supernova production and we search for WDs in the Gaia DR2 database within open clusters whose turnoff masses are as high as 15 M .

2. THE WHITE DWARF SURVEY

The Gaia DR2+ catalogue provides a 5-parameter astrometric solution (α, δ, µα, µδ, π) for more than 1.3 billion sources. The catalogue is only complete for G magnitudes between ∼12 and 17 with a general limiting G magnitude of approximately 21 (Gaia Collaboration et al. 2018). However, this value can be as bright as G = 18 in dense areas of the sky due to blending from other sources. Considering these restrictions, we primarily surveyed clusters from 10 Myr (turnoff mass ∼19.3 M ) up to 500 Myr (turnoff mass 2.9 M ) within 1 kpc of the Sun. A 1 M hydrogen atmosphere WD that has been cooling for ∼250 Myrs has an absolute G magnitude of ∼11.8 (B´edardet al. 2020), corresponding to an apparent G magnitude of 20.3 at 500 pc. Since young clusters are near the Galactic plane, at this distance we can generally expect about 0.7 mag of extinction, placing the WD close to the Gaia limit of detection. The current paradigm is that WDs form when a star with mass less than ∼8 M expels its outer layers after the red giant phase, leaving only a core remnant behind. Without fusion occurring, the degenerate core slowly radiates its thermal energy, causing the WD to become increasingly faint and cool. The limitations in the completeness of the Gaia catalogue, coupled with the typical faintness of WDs, results in a bias toward young and nearby open clusters as hosts for massive WDs. Young clusters with higher turnoff masses are more likely to produce higher mass WDs which have not yet cooled beyond Gaia’s photometric limit. Additionally, the closer the cluster is to the Sun, the brighter the sources will appear. Nearby clusters can be older and still have observable massive WDs while distant clusters must be very young for potential high-mass WDs to be observable. The complete list of the 386 surveyed clusters was compiled from WEBDA data. Of this sample, 262 clusters are in the 10-500 Myr age range and are located within 1 kpc of the Sun, 111 have distances of 1-1.5 kpc and ages <220 Myr (young + distant) and 8 are in the 500 Myr-2.5 Gyr age range with distances < 400 pc (old + close). The first group is the best suited to look for WDs that might have evolved from massive main sequence stars, but we extended our search to the latter two groups because they also might still contain massive WDs that are observable in Gaia. The distribution of the ages and distances of these clusters are shown in Figure1. Also included are the Hyades and NGC 2099 (M37) who do not fit our age restrictions but contain known massive WDs we wished to rediscover. Four extremely young clusters IC 5146, Lynga 14, NGC 6383, Ruprecht 119, with ages <10 Myr, were also added as we wanted to remain agnostic to the upper mass limit for WD formation and any WDs present in these clusters could be derived from high-mass progenitors at the upper limit of the IFMR. Massive White Dwarfs in Young Star Clusters 3

We queried the Gaia DR2 archive for each cluster using equatorial cluster centre coordinates as the target and 2× the angular diameter as the search radius, using data from the DAML02 database (Dias et al. 2002). In each cluster, we retrieved the top 500,000 stellar results. Choosing the search radius as twice the literature diameter is an arbitrary choice; we expect that it should allow for the majority of cluster members to be included, accounting for a possible underestimate in the literature diameter while not searching too widely and flooding the data with non-cluster stars. No further preliminary cuts were made to reduce contamination.

Figure 1. Distance and age of all WEBDA clusters within our survey range (blue circles). The filled circles indicate the clusters that we included in our survey. As can be seen here, the completeness of our survey is very high (> 97%) for 7.0 ≤ log (Age) ≤ 8.5 for distances ≤ 1500 pc.

3. DETERMINING CLUSTER PARAMETERS In tandem with the search for massive WDs, new cluster parameters were determined for every identifiable clus- ter to allow for membership determination and follow-up analysis. We identified cluster members through cuts in positional space, parallax and proper motions, assuming that the probability distributions are well approximated by Gaussian probability density functions (PDFs): 2-dimensional in proper motion and equatorial positional space and 1-dimensional in parallax. Reported cluster centres and errors in our survey table (Table5) correspond to the means and standard deviations of the Gaussians. We fitted Gaussian functions to kernel density estimates (KDEs) in each space. KDEs are used as a method to obtain a density map for a collection of coordinates1. We chose to use KDEs instead of histograms for the purpose of fitting Gaussian models to density distributions for three main reasons. Firstly, discretely binned data leads to a loss of information, whereas in a KDE, each coordinate is uniquely assigned a density. This provides the model fitting algorithm with a larger number of points to improve the quality of the fit, which is even more important when working with open star clusters that can be very sparse, with sometimes less than 100 members. Secondly, the number of bins in an histogram needs to be properly determined for each data set, while KDEs are determined by two parameters: kernel and bandwidth h. We chose a Gaussian kernel, which is the most common choice, for which the bandwidth h

1 We use the scikit-learns KernelDensity class in Python (Pedregosa et al. 2011). 4 Richer et al. is equivalent to the standard deviation σ. We found the ‘best’ bandwidth to be always close to 0.1 in proper motion and parallax and close to 0.5 in position2. Finally, the KDE is useful as a visual aid. We show an example in Figure2: when the radius of the cut in proper motion is too large (upper panels), we see an excess density of stars towards the right hand side of the KDE because of contamination from the galactic disk, which causes the fitted standard deviation to be overestimated. The distortion in the KDE in the direction of the contamination from the field is helpful to iteratively adjust the subset of candidate stars chosen for fitting, to find a balance between including as many cluster members as possible and reducing the contamination.

Figure 2. KDE colormap with h=0.1 (left) and proper motion selection (right) for M47 (NGC 2422). The KDE was generated from a cut in proper motion with a radius 1 mas yr−1 (top) and 0.5 mas yr−1 (bottom), also indicated by the solid blue line in the right-hand plots. A 2σ ellipse from the resulting fit is shown as a red dashed line. Also visible is the large, dense region of contaminating stars from the galactic disk and NGC 2423 (below, circled in green). From this figure it is clear that clusters are required to have a significant peculiar motion with respect to the galactic disk to be separated by a proper motion cut and avoid important contamination.

The limitation of this manually conducted survey is that a cluster needs to be clearly identified in proper motion space (see Fig.2). Of the total sample of 386 clusters, 219 were distinguishable in proper motion space and 167 were not. Cantat-Gaudin et al.(2018) used Gaia data to derive cluster parameters for 1229 nearby open clusters using the unsupervised membership code UPMASK. Whenever the identification of clusters in contaminated and crowded fields

2 The ‘best’ bandwidth was determined by scikit-learns GridSearchCV algorithm in Python (Pedregosa et al. 2011). Massive White Dwarfs in Young Star Clusters 5 was not possible visually in proper motion space, we used this catalog instead. However, out of 169 clusters which were not identifiable by eye in proper motion, 110 also do not appear in Cantat-Gaudin et al.(2018). We applied astrometric cuts in proper motion and parallax space, assuming the cluster population to be well described in each dimension by a Gaussian PDF. We find that retaining only stars that lie within 2-σ of the mean proper motion and parallax of the cluster strikes the best balance between retaining as many ‘real’ cluster member as possible and avoiding contamination from field stars. Employing a 3-σ cut instead leads to an important contamination, which affects later analysis such as subsequent fit quality, cluster reddening, extinction and cluster age determination. Therefore, only sources within 2-σ of the mean proper motion and parallax are considered likely cluster members. However, due to typically high uncertainty in Gaia proper motion and parallax data for faint sources, once cluster parameters were fully determined, we tested 4-σ cuts to probe the presence of WDs farther from the cluster centres whose error bars might intersect the 2-σ region even if nominal values do not. After making 2-σ cuts in proper motion space, we analyzed KDEs in parallax space. We assumed that the parallax data could be described by the sum of two 1-D Gaussians: one describing the distribution of the field sources (noise) and one the distribution of the cluster. Fits for these two Gaussians were performed on the KDE. The parallax centre for the noise was typically in the range 0.1-0.5 mas. If the cluster is ‘nearby’ and has a parallax centre ≥1.5 mas, the Gaussian describing the noise could be omitted from the fitting. Describing the data with a pair of Gaussians becomes extremely useful for clusters whose parallax centre is ≤ 1.5 mas as the noise does not displace the fitted parallax centre and does not cause the fitted σ to be overestimated. We then retain all the stars that are within 2 σ from the mean. After making cuts in parallax space, we have completed all astrometric cuts. We then fit a Gaussian to a KDE of the equatorial position distribution of remaining sources. We carry out photometric filtering by removing all objects with the photometric excess flag (phot bp min rp excess factor), E ≥ 1.5. E is the sum of GBP (phot bp mean flux) and GRP (phot rp mean flux) over the total G band flux (phot g mean flux) and is expected to be larger than 1 by a small factor, with wide de- viation suggesting lower photometric precision (Evans et al. 2018). Lindegren et al.(2018) has recommended keeping sources which satisfy

2 2 1 + 0.015(GBP − GRP ) < E < 1.3 + 0.065(GBP − GRP ) . (1)

The upper bound of equation (1) removes very faint sources that might have been rejected by a filtering on the photometric precision (Arenou et al. 2018). These sources appear most abundantly in the galactic plane, where many of our surveyed clusters lie. Furthermore, faint sources with imprecise photometry could be mistaken for interesting WDs. The value of 1.5 was selected as the upper threshold for all clusters rather than filtering sources individually. A lower cut-off as given in equation (1) is primarily needed to filter perturbations by close-by sources (Arenou et al. 2018) for observing very distant sources, but typically only removes a small number and was deemed unnecessary for our survey. To determine the cluster reddening, we considered only cluster members that had complete reddening and extinction data from the Gaia DR2 catalogue. Due to a lack of adequate parallax and photometric precision, Gaia DR2 does not determine astrophysical parameters for sources with G ≥ 17.068766 (Andrae et al. 2018). For the remaining sources Andrae et al.(2018) use distances determined via parallax and G, GBP, and GRP magnitudes as inputs to train the machine learning algorithm Extra-Trees (Geurts et al. 2006), which, when combined with extinction models, allows it to compute the G-band extinction, AG, and the reddening, E(BP-RP) = ABP − ARP, for each source. Extra-Trees is unable to extrapolate beyond the intervals of the training variable, as a result they avoid negative estimates for AG and E(BP-RP). This leads to some sources being given zero as their 1σ lower-bound extinctions. For consistency, we removed these sources from our reddening calculations. Additionally, a number of sources suffered from degeneracies due to model stars with varying astrophysical parameters having identical apparent magnitudes. Extra-Trees cannot distinguish between these, resulting in some sources having very large uncertainty intervals. Sources whose extinction and reddening uncertainty intervals failed to meet certain conditions were not retained in Gaia DR2 (Andrae et al. 2018). Based on these constraints, only ≈ 42% of the sources in our samples after the astrometric cuts had complete reddening and extinction data. Using these sources we calculated the variance-weighted means to estimate the overall reddening and extinction of each cluster. The error in these estimates was found by first determining the reliability weight-based unbiased sample variance, which was used alongside the number of sources to determine the standard error in each mean. Though this helps to account for the increased statistical error in the clusters with relatively few 6 Richer et al. members, we emphasize that some of these values were calculated based on just a handful of sources and may not be overly reliable. With cluster reddening and extinction determined, an extinction, colour and distance corrected colour-magnitude diagram could then be constructed to identify any potential WDs, their cooling times, and the cluster age. We note that in the late stages of preparation of this manuscript, a related survey appeared on the archives (Priˇsegen et al. 2020) that carried out a similarly motivated search for cluster WDs. Aside from some differences in methodology and scope, one important difference between our search and that one is that we have verified many of our best candidates with spectra, a critical component in establishing the properties of candidate cluster WDs. 4. EXPECTED NUMBER OF WHITE DWARFS IN SELECTED STAR CLUSTERS Although WDs are the final evolutionary point for ninety-eight percent of all the stars in our galaxy, studies have shown that the observed number of WDs in many clusters is significantly smaller than expected (Kalirai et al. 2009; Fellhauer et al. 2003). A possible explanation of this discrepancy are natal WD velocity kicks, occurring if the red giant precursor asymmetrically ejects its outer layers, driving the WD in the opposing direction. These kicks could potentially eject a WD from its parent cluster, resulting in a deficiency of observed WDs (Fellhauer et al. 2003). While a total of 387 clusters were surveyed for massive WDs in this work, here we present an estimate of the number of WDs expected in each cluster, hNWDi, for 163 of the clusters in our sample with a well-defined turnoff (so that isochrones could be reliably fit) and good reddening values (generally σE(BP-RP)≤ 0.05). Using the same filtered data files as in our massive WD search, we first produced CMDs for each cluster in order to determine its age. We converted the Gaia apparent magnitudes to absolute magnitudes using distances determined by cluster centre parallaxes and extinctions derived from reddening values (E(BP − RP )). While the CMDs act as an excellent visual aid when determining cluster ages, it is the information contained within the isochrone of the associated age that is 3 key in determining hNWDi. All isochrones in this study were obtained from the STEV CMD server and use Gaia DR2’s photometric system and passbands from Ma´ızApell´aniz & Weiler(2018). Solar metallicity was used for all isochrones. To expedite the age determination, when available, we used the ages found by machine learning in Cantat-Gaudin et al.(2020) as our first guess for isochrone fitting. We then visually inspected how well the isochrones reproduced the data on the Gaia CMD. Whenever the fitting was satisfactory, we kept the same ages as in Cantat-Gaudin et al. (2020); as the authors mention that the error in log(t) is between 0.15-0.25 for their method, we employ an error of 0.20 in log(t) for each cluster, where t is the age in Myr. For the clusters that are absent from Cantat-Gaudin et al. (2020) or for which the first-guess isochrone fits the cluster data poorly, we manually fit isochrones on each cluster to find the age. Cluster-specific factors such as contamination by field stars and poor definition of the turnoff point affect the uncertainty in our visual age determinations. These uncertainties were computed by manually adjusting the age of the isochrone to best fit the turnoff stars of the cluster, finding a maximum and a minimum age for which the isochrone is still a good fit. The value we quote for the age is then the midpoint between the two, and the error is half the difference. It is also important to note that we were unable to determine ages and thus WD number expectation values for some of the clusters. Reasons for this include poorly determined observational parameters, highly contaminated clusters and the absence of sufficient turnoff stars. Cluster ages and uncertainties are indicated in Table5, where a † denotes an age from Cantat-Gaudin et al.(2020), ‡ indicates manual age determination from this work and * indicates that no age determination was possible. For each cluster, from the isochrone, we assume a Kroupa(2001, 2002) initial mass function (IMF), i.e. the initial distribution of masses of the stars in the cluster dN/dM. From the IMF we could compute the number of WDs that have already been produced by the cluster, or hNWDi, by integrating the IMF from the mass of the stars that are currently producing white dwarfs (Minit,WD) to a chosen upper mass limit for the production of white dwarfs (in particular, we used 8 M ). Of course we had to normalize this number to the actual number of stars in the cluster. In order to do so, we used the brightest main-sequence stars: we sorted all cluster stars by brightness and obtained the number of main-sequence stars in the brightest third of the cluster (N1), up to the turn-off, and divided it by the number of stars in the same range predicted by the IMF, i.e. we divided N1 by the integral of dN/dM between the mass of the faintest of the selected stars (Minit,3) and the mass of the turn-off (Minit,TO). The turnoff point for each cluster was identified by finding the highest temperature value reached by stars on the main sequence. We chose

3 http://stev.oapd.inaf.it/ Massive White Dwarfs in Young Star Clusters 7 to focus on the brightest one-third of stars as a trade-off between having more stars and hence better statistics and the fact that lower mass stars may have already been expelled from the cluster through dynamical interactions. The number of expected WDs for each cluster was therefore obtained as:

" #−1 Z Minit,TO dN Z 8M dN hNWDi = N1 dM dM. (2) Minit,3 dM Minit,WD dM Regardless of whether the age was determined here or obtained from Cantat-Gaudin et al.(2020), the error in hNWDi was computed from the error on the age, by taking the absolute value of the difference between the number of expected white dwarfs for the nominal age plus the error and minus the error and dividing by two. Since these errors arise directly from the uncertainty in the cluster age, the uncertainty in hNWDi varies dramatically from cluster to cluster. The hNWDi and corresponding uncertainties are presented in Table5. The total number of white dwarfs that we expect to have been produced by these clusters is nearly 1,100 if the maximum initial stellar mass for white dwarf formation is 8M . On the other hand, if white dwarfs are produced from stars only up to 6M , the expected number of white dwarfs is 30% smaller at 750. Depending on the age of the cluster, the effect of the upper mass for white-dwarf formation can be modest (about 10%) or large (a factor of several). However, because the expected number of white dwarfs is dominated by the richer clusters which happen to be older as well, the net effect is a 30% decrement. Increasing the upper limit on white dwarf formation to an initial stellar mass of 12M increases the number of expected white dwarfs by 30% to nearly 1,400.

5. SURVEY RESULTS: ASTROMETRY, PHOTOMETRY AND SPECTROSCOPY OF WD CANDIDATES In our narrow search (a 2σ cut in proper motion and parallax), we identified twenty-four WD candidates in the direction of young open star clusters. Of these twenty-four, thirteen were already known cluster members, well-studied in the literature (see Cummings et al.(2018, 2016); Curtis et al.(2013); Dobbie et al.(2012); Dobbie et al.(2004); Gianninas et al.(2011); Kalirai et al.(2008)) and another five have masses, inferred from their location in the Gaia CMD, that appear inconsistent with cluster membership, leaving six new potential high mass WD candidates. Spectra of each of these six candidates were obtained with Gemini North or South in order to determine their surface gravity, temperature and hence their cooling age and eventually their mass. All this data together allowed for a critical assessment of the cluster membership of each candidate. As mentioned above, because of the high uncertainty in Gaia proper motion and parallax data for faint sources, we relaxed our parameters to search for white dwarfs that are within 4-σ from the cluster centres in either parallax or proper motion and we discovered an additional four high mass WD candidates, that we followed-up with spectra from Gemini. A handful of well-studied WDs met our proper motion and parallax criteria but did not appear in our final narrow search results. Two of these were missed because their excess factors were too high, while another five did not appear in the original Gaia queries. The WDs which missed the queries likely missed as a result of being in a particularly nearby cluster with a wide angular extent, in which case the 500,000 returned results was insufficient. The outstanding example of this was the Hyades Cluster, which covers at least 100 square degrees on the sky. It would not be possible to query the Gaia database to include the enormous number of stars in this area. It is possible this issue may have led to us missing additional WDs in other near and large clusters, but we expect the impact to be minor at worst. Table1 lists all of the identified candidate WDs along with the handful of well-studied WDs appearing in Cummings et al.(2018) which were missed for the aforementioned reasons. The † in the comments indicates that the WD passed the 4-σ but not 2-σ cuts, ‡ is for WDs which passed 2-σ cuts but had excess factors which were too high, and the ∗ signifies WDs which were missed by the Gaia queries entirely. The remaining objects listed in Cummings et al.(2018) that did not make our cuts are included in Table6 in the appendix. This section provides the details of the astrometric search in the direction of each of the ten clusters that we discovered to potentially host a new massive WD. As part of the process, we develop the cluster’s CMD, fit isochrones (Bressan et al. 2012) to it in order to estimate the cluster age, and include WD cooling sequences in the CMD in order to photometrically estimate the mass and cooling age of the WD. We also analyse the Gemini spectra of each of the WDs and fit spectral models to the Balmer absorption lines, deriving the WD’s surface gravity (log g) and effective temperature (Teff ). Our fitting method to the Balmer lines is similar to the routine outlined in Liebert et al.(2005): we fit the spectrum with a grid of spectroscopic models combined with a polynomial in λ (up to λ9) to account for calibration errors in the continuum; we then normalize the spectrum using this smooth function picking normal points at a fixed distance 8 Richer et al.

Table 1. Potential Cluster Member White Dwarfs Identified

Cluster WD

Name E(Bp − Rp) Gaia Source ID Gobs (Bp - Rp)obs G0 (Bp - Rp)0 Comments Alessi 8 0.149±0.022 5888965556642170624+ 20.818±0.013 -0.334±0.140 11.360±0.228 -0.483±0.141 followed-up Alessi 21 0.100±0.011 3050806942132626048+ 20.360±0.001 -0.293±0.140 11.357±0.018 -0.393±0.140 followed-up† ASCC 47 0.136±0.015 5529347562661865088 18.714±0.003 -0.509±0.042 8.957±0.241 -0.645±0.045 followed-up ASCC 113 0.078±0.006 1871306874227157376 19.833±0.004 -0.435±0.107 10.889±0.010 -0.513±0.107 followed-up† M39 0.044±0.008 2170776080281869056 19.193±0.003 -0.179±0.050 11.732±0.015 -0.222±0.051 followed-up† M44 0.096±0.013 5597682038533250304 19.567±0.004 -0.075±0.073 10.309±0.172 -0.171±0.074 low mass [1] M44 0.119±0.009 659494049367276544 18.215±0.002 -0.134±0.024 11.603±0.367 -0.253±0.024 well-studied [3]∗ M44 0.119±0.009 661010005319096192 18.356±0.001 -0.075±0.017 11.743±0.367 -0.194±0.017 well-studied [3]∗ M44 0.119±0.009 661270898815358720 17.682±0.002 -0.290±0.025 11.069±0.160 -0.409±0.027 well-studied [3] M44 0.119±0.009 661297901272035456 18.413±0.002 -0.093±0.025 11.114±0.160 -0.212±0.021 well-studied [3] M44 0.119±0.009 661311267210542080 17.682±0.002 -0.024±0.025 11.780±0.160 -0.143±0.019 well-studied [3] M44 0.119±0.009 661353224747229184 17.883±0.001 -0.168±0.017 11.271±0.160 -0.287±0.019 well-studied [3] M44 0.119±0.009 661841163095377024 18.342±0.001 -0.056±0.018 11.729±0.367 -0.175±0.018 well-studied [3]∗ M44 0.119±0.009 662798086105290112 17.960±0.002 -0.171±0.017 11.348±0.367 -0.290±0.017 well-studied [3]∗ M44 0.119±0.009 664325543977630464 17.999±0.002 -0.141±0.033 11.387±0.160 -0.260±0.035 well-studied [3] M44 0.119±0.009 665139697978259200 18.026±0.002 -0.121±0.033 11.413±0.367 -0.240±0.033 well-studied [3]∗ M47 0.149±0.006 3029912407273360512 19.796±0.005 -0.134±0.106 11.071±0.233 -0.283±0.106 followed-up NGC 2516 0.089±0.004 5290834387897642624 19.165±0.002 -0.261±0.069 10.889±0.297 -0.350±0.069 well-studied [2] NGC 3114 0.134±0.004 5256341647300346496+ 20.929±0.018 -0.450±0.532 10.537±0.290 -0.584±0.532 followed-up NGC 3532 0.061±0.006 5340154429370971648+ 20.703±0.012 0.353±0.394 12.046±0.497 0.292±0.394 low mass [1] NGC 3532 0.061±0.006 5338636244376571136+ 20.093±0.006 0.148±0.165 11.437±1.144 0.087±0.165 well-studied [2]‡ NGC 3532 0.061±0.006 5340149103605412992+ 20.189±0.007 -0.382±0.235 11.533±1.144 -0.443±0.255 well-studied [2]‡ NGC 6087 0.292±0.012 5832123141956843648+ 20.753±0.007 0.123±0.360 10.189±0.530 -0.169±0.360 low mass [1] NGC 6633 0.244±0.018 4477214475044842368 18.914±0.004 0.014±0.091 10.426±0.214 -0.230±0.093 low mass [1] Pleiades 0.096±0.005 66697547870378368 16.614±0.001 -0.431±0.013 10.745±0.149 -0.527±0.013 well-studied [4] Ruprecht 147 0.202±0.016 4087806832745520128 18.836±0.004 -0.167±0.069 10.974±0.130 -0.369±0.070 well-studied [5] Ruprecht 147 0.202±0.016 4183919237232621056 18.688±0.004 0.004±0.057 10.826±0.130 -0.198±0.060 well-studied [5] Ruprecht 147 0.202±0.016 4183928888026931328 18.803±0.003 0.012±0.066 10.941±0.130 -0.191±0.068 well-studied [5] Ruprecht 147 0.202±0.016 4183937688413579648+ 19.106±0.004 0.073±0.128 11.243±0.130 -0.130±0.129 well-studied [5] Ruprecht 147 0.202±0.016 4184148073089506304 19.628±0.005 0.028±0.084 11.765±0.130 -0.174±0.085 well-studied [5] Ruprecht 147 0.202±0.016 4184169822810795648 18.894±0.005 -0.021±0.087 11.032±0.130 -0.223±0.088 well-studied [5] Stock 2 0.378±0.009 506862078583709056 19.646±0.005 -0.080±0.088 10.978±0.133 -0.458±0.089 followed-up Stock 2 0.378±0.009 507362012775415552 19.794±0.005 0.175±0.105 11.126±0.133 -0.203±0.106 low mass [1] Stock 12 0.140±0.012 1992469104239732096 19.099±0.003 -0.126±0.055 10.581±0.019 -0.266±0.056 followed-up† vdB Hagen 23 0.108±0.026 5541515415474844544 20.269±0.006 -0.308±0.170 11.776±0.185 -0.416±0.172 followed-up

Notes. + indicates the object does not appear in the Gentile Fusillo et al.(2018) catalog. † indicates the object fell just outside the narrow search range, i.e. a 2-σ cut in parallax and proper motion of the cluster but was nevertheless included in our sample of followed-up WDs. ‡ indicates an object that passed the 2-σ cuts but had an excess factor > 1.5, while ∗ indicates the object missed the original Gaia queries, these well-studied objects were included for completeness. [1] WD appeared to be below 0.6 M in the cluster CMD and was judged to be a non-member and was not pursued further. [2] Dobbie et al.(2012), [3] Dobbie et al.(2004), [4] Gianninas et al.(2011), [5] Curtis et al.(2013) but initial mass below 2.5 M and cluster too old (Marigo et al.(2020)).

in wavelength to the lines and finally use our grid of model spectra to fit the Balmer lines and extract the values of log g and Teff . The nonlinear least-squares minimization method of Levenberg-Marquardt is used in all our fits. We employ the models of pure hydrogen atmospheres developed by Tremblay et al.(2011) for most of the objects and the hydrogen atmospheres polluted by metals developed by Gianninas et al.(2010) for the hot WD in ASCC 47. This WD is so hot (Teff > 110,000 K) that the levitation of metals caused by the resultant high radiation pressure cannot be ignored. These fits are shown in Fig. 13 and the resulting parameters are listed in Table3. A complete listing of all the clusters surveyed for massive WDs can be found in Table5. The ten clusters, together with their ages as derived from our new analysis of Gaia DR2 data, are listed in Table2. For all the candidates we provide the WD mass as well as that of its precursor if the WD appears to be a member of its respective cluster. As we shall see, several WD candidates turned out to be probable foreground or background objects and a few were not even WDs at all! Massive White Dwarfs in Young Star Clusters 9

Figure 3. Astrometric data for vdB-Hagen 23. Proper motion (left), KDE of parallax values (centre) and equatorial position (right). Red dashed lines indicate 1 and 2 sigma contours. Blue star with error bars indicates the WD candidate values.

5.1. vdB Hagen 23 vdB Hagen 23 is an extremely sparse cluster with a WEBDA age of only 14 Myrs. From the CMD Fig. 14 (leftmost panel), it is clear that the cluster is very young (our best estimate is 55±20 Myr) and the WD, if really a cluster member, appears massive (∼1.1 M ). It is surprising and remarkable that such a young cluster seems to potentially host a WD member. If confirmed this would mean a precursor mass of about 15 M . As can be seen in Fig.3, the WD candidate is well within the 2σ limits of all the astrometric criteria, though with rather large errors in all these three quantities.

From the position of the WD in the CMD, however, the WD appears much too faint and cool: cooling models from the Montreal group (Gianninas et al.(2010)) indicate that the time for a WD of about 1.1 M to cool to the absolute G magnitude that we obtain using the parallax of the WD (11.775) and the observed color (Bp − Rp = −0.416) is about 190 million years, significantly older than the cluster. The analysis of the spectrum of the WD (Figs. 12 and 13), provides a surface gravity and an effective temperature (Table3) that imply a WD mass near 0.63 M , in strong disagreement with the photometric estimate. If we apply the cluster parallax to the WD instead of its own parallax, this yields a WD that is only 0.2 magnitudes brighter, not nearly enough to explain the difference. The only reasonable way in which to bring these contradictory estimates into agreement is to assert that the WD is in fact much closer to us than the cluster, and hence unrelated to it. The WD would need to have a parallax that is even larger than its 2σ limit to explain its absolute magnitude — a parallax that puts it at about half the cluster distance. We conclude from this discussion that the WD in the direction of vdB-Hagen 23 is not a cluster member, even though the astrometric data make a plausible case for membership. This example illustrates that, even with our very strict requirements for cluster membership, the large errors in parallax and proper motion of the WDs, due to the fact that they are rather faint objects, often translate into a reasonable possibility of finding false-candidates. For this reason, it is critical to examine all possible data for every candidate, including the spectrum, before deciding on cluster membership.

5.2. Alessi 21

In Fig.4 we present the astrometric data relating to the membership of the WD in the direction of the cluster Alessi 21. The WD’s parallax is within 1σ of the cluster mean value, while its proper motion and position with respect to the bulk of the cluster members puts it as an outlier in both these latter quantities. The WD is about the faintest object in Alessi 21 with a measurable proper motion, so while it does not make our cut for membership based on proper motion, its error is large (Fig.4, left panel). In addition, it is fairly common that cluster WDs do not generally lie near their respective clusters’ centre. This may be the result of a small natal kick given to the newly formed WDs (Fellhauer et al. 2003). 10 Richer et al.

Figure 4. Astrometric data for Alessi 21. Proper motion (left), KDE of parallax values (centre) and equatorial position (right). Red dashed lines indicate 1, 2 sigma. Blue star with error bars indicates WD candidate.

The cluster CMD, Fig. 14 (second panel from the left), is that of a young cluster with an age of ∼60±20 Myrs. This age is twice as old as the WEBDA age of 30 Myrs. The photometric mass estimate for the WD from the CMD is ∼1.0 M if it is a cluster member. The WD cooling time to reach the observed magnitude (MG = 11.33) and colour ((Bp − Rp)0 = -0.40) is 121 Myrs. This cooling age is considerably longer than the age of the cluster suggesting that the WD is not a member. More information on the WD’s properties are contained in Figure 13 where the Gemini spectrum of the WD is displayed. Fitting spectral WD models to this object yields log g = 8.36±0.03 and an effective temperature of 23,500±200 K. This is well-modeled by a WD of mass 0.85 M with a cooling age of 70 Myrs. A WD of this mass is not entirely consistent with the photometric mass as can be seen in Fig. 14, but it still lies well within its 1σ error bars. Even a cooling age for the WD of 70 Myrs is longer than the cluster age, leaving no time for main sequence evolution. We conclude from this discussion that the WD in Alessi 21 is unlikely a member of the cluster.

5.3. ASCC 47 The ASCC 47 WD can be considered a cluster member with a high degree of confidence. The astrometric data exhibited here together with our earlier publication on this WD and its host cluster (Caiazzo et al. 2020, Fig. 14), make a very strong case for membership. The astrometric data provide the strongest case for membership of any WD found in our survey with all properties lying within about 1σ of the mean cluster values. The cluster age from the CMD is 90±20 Myrs (Caiazzo et al. 2020) and the photometry suggests a WD that is extremely hot and luminous. As we showed in Caiazzo et al., the WD is a hot magnetic DA, in fact the hottest and youngest WD known in any open star cluster. Its temperature is estimated to be 110,000 K and it has been cooling for only 250 kyrs. Analysis of the Zeeman splitting in the H-α line suggests that the WD is threaded by a magnetic field of about 1 MG on its surface.

The spectroscopic fit that we show in Fig. 13 employs non-magnetic models for a polluted hydrogen atmosphere developed by Gianninas et al.(2010). The use of polluted models is crucial for such a hot white dwarf because the levitation of metals in the atmosphere due to high radiation pressure modifies the shape of the Balmer lines. However, we showed in Caiazzo et al. that the values obtained from the fit of non-magnetic models is not reliable, especially for the value of the surface gravity, because when the magnetic field strength is close to 1 MG, gravity and magnetic field are degenerate in broadening the lines. In Table3 we therefore report also the photometric value of log g, which is the one we use in the determination of the mass of this WD.

5.4. Alessi 8 and NGC 3114 Alessi 8 appeared to be a promising WD cluster candidate. All its astrometric parameters lay within about 1σ of the cluster mean properties (Fig.6) while its CMD suggested a cluster age near 100 Myrs and a massive WD ∼1.0 M . However, a Gemini GMOS spectrum indicated that the object was not a WD. Similar comments apply to NGC 3114. In this case, the WD parallax agreed well with that of the cluster but it was somewhat of an outlier in proper motion and position. Here, the cluster age was estimated at ∼130 Myrs with the WD photometry implying a WD Massive White Dwarfs in Young Star Clusters 11

Figure 5. Astrometric data for ASCC 47 and its WD. Proper motion (left), KDE of parallax values (centre) and equatorial position (right). Red dashed lines indicate 1, 2 sigma. Blue star with error bars indicates WD candidate.

Figure 6. Astrometric data for Alessi 8. Proper motion (left), KDE of parallax values (centre) and equatorial position (right). Red dashed lines indicate 1 and 2 σ limits. Blue star indicates WD candidate with its associated error bars. mass just below 1.0 M , but in this case the errors in the photometry were very large (see Table1). Again, a Gemini spectrum indicated the object was not a WD. We do not discuss these two stars any further here.

5.5. Messier 47 (NGC 2422)

The WD in M 47 was discussed by our group in an earlier paper (Richer et al. 2019). The new analysis of the astrometric data presented here confirm the strong case for membership of the WD in the cluster. All the key astrometric parameters of the WD are within about 1σ of the mean cluster values. The cluster itself is moderately rich and has an age, based on the isochrone fit in Fig. 14, of about 150 Myrs. The spectrum of this WD was discussed in detail in Richer et al.(2019). It shows that the WD is a magnetic DB (helium atmosphere) with a mass of 1.06 M . Analysis of the Zeeman splitting in the helium lines indicates a magnetic field of about 2.5 MG. The WD cooling models displayed in Fig. 14 for this cluster are for DB stars and they seem to suggest that the WD has only a moderate mass of slightly under 0.8 M . The reason for this discrepancy is that, as we showed in our earlier paper using more extensive photometry than just that of Gaia (VPHAS+ Pan-STARRS), the WD has an infrared excess. The rather red Gaia colours are sensitive to this excess whereas in our original paper we established the photometric mass of the WD using VPHAS+ u− and g−band data which are much less sensitive to the red excess. 12 Richer et al.

Figure 7. Astrometric data for M47 (NGC 2422). Proper motion (left), KDE of parallax values (centre) and equatorial position (right). Red dashed lines indicate 1, 2 sigma. Blue star indicates WD candidate.

Figure 8. Astrometric data for Stock 2. Proper motion (left), KDE of parallax values (centre) and equatorial position (right). Red dashed lines indicate 1, 2 sigma. Blue star indicates WD candidate.

5.6. Stock 2 The WD seen in the direction of Stock 2 has a high probability of being a cluster member with all its astrometric parameters lying within about 1σ of that of the mean cluster values. This is quite a rich cluster, one of the two richest (together with M 47) of all those in which we identified a new massive WD member in this survey.

The age of the cluster from its CMD is quite uncertain. As can be seen in Fig. 15 (left panel), there is an enormous amount of scatter just below the turnoff region. It is not obvious what the source of this scatter is; it may be differential reddening, rotation of upper main sequence stars or binarity. We have established the cluster age from the three giant stars which together suggest a cluster age of 225±50 Myrs. This can be compared with the WEBDA value of 170 Myrs. Our survey actually located 2 WDs in the direction of Stock 2, as can be seen in Fig. 15). The cooler and fainter one of these seemed to be too low in mass to be a cluster member, so we did not pursue it further. It is a likely foreground object. In fact, the parallax for this star seems to confirm somewhat this suggestion, implying that it is about 10% closer than the cluster. The cluster CMD suggests a photometric mass for the WD of just under 1 M if it is a cluster member. The color, (Bp − Rp)0 = −0.46 , suggests a temperature of 29,000 K and together with the absolute magnitude (MG = 10.98 ) implies that the time it took the WD to cool to these values is 74 Myrs (Gianninas et al.(2010)). Subtracting this Massive White Dwarfs in Young Star Clusters 13

Figure 9. Astrometric data for ASCC 113. Proper motion (left), KDE of parallax values (centre) and equatorial position (right). Red dashed lines indicate 1, 2 sigma. Blue star indicates WD candidate. from the cluster age of 225 Myrs leaves 151 Myrs for the main sequence lifetime of the WD precursor. A star with this hydrogen burning lifetime has a mass of 4.5±0.2 M , which would be the mass of the precursor of this WD. Analysis of the spectrum of the WD yields log g = 8.58 ± 0.05 and an effective temperature of 25, 400 ± 300 K. This is well-modeled by a WD of mass 0.99 M with a cooling age of 110 Myrs. A WD of this mass is entirely consistent with the photometric mass as can be seen in Fig. 15. A cooling age for the WD of 110 Myrs implies that the progenitor spent 115 million years on the main sequence in this 225 Myr cluster. A star of mass 5.0 M spends this amount of time in the main sequence phase. Since the spectroscopic results are expected to be more precise, we adopt these for the properties of the WD in Stock 2.

5.7. ASCC 113 The Gaia parallax of the WD in the direction of ASCC 113 is within 1σ of the mean cluster value while the proper motion and location on the sky put it as a slight outlier. The cluster CMD seen in Fig. 15, second panel from the left, implies a cluster age of about 240±40 Myrs and suggests a photometric mass for the WD near 1.0 M .

Fig. 12 displays our full Gemini-North spectrum of the ASCC 113 WD while Fig. 13 shows the best spectral fits to the four Balmer lines Hβ through to H. The stellar parameters derived from these fits are log g = 8.71 ± 0.07 and T = 25, 400±300 K. These WD properties are well-modeled by a WD of mass 1.06 M with a cooling age of 160 Myrs. This WD mass, as can be seen in Fig. 15 is also consistent with the photometry of the WD given the photometric errors. This cooling age, coupled to the age of the cluster yields the WD precursor’s main sequence lifetime: about 80 Myrs. From the Padova stellar evolution models (Bressan et al. 2012), we find that a star of 5.8 M spends 80 Myrs on the main sequence. The ASCC 113 WD is thus tied with the WD in M 47 as the most massive WD we found in our survey for massive cluster WDs. The M47 WD is, however, quite a different WD, being a magnetic DB star.

5.8. Messier 39 (NGC 7092) The astrometric data for the WD in Messier 39 present a reasonably strong case for its membership in the cluster. The parallax is well within 1σ of the cluster mean, the position on the sky is within 2σ while the proper motion is just outside 2σ. The CMD of this cluster, Fig. 15, suggests an age near 280±20 Myrs and yields a photometric mass for its WD near 0.9 M . The spectrum of the WD was discussed in detail in Caiazzo et al.(2020) and yielded log g = 8.87 ± 0.07 and a temperature of 18, 400 ± 300 K. This apparently high gravity is partially due to the presence of a magnetic field which has the effect of broadening the spectral lines, hence mimicking a higher mass WD. The photometric log g, which we use in this case as it is largely unaffected by the presence of the magnetic field, suggested a value of 8.54 ± 0.04 for log g and together with the temperature yielded a mass of 0.95±0.02 M . 5.9. Stock 12 14 Richer et al.

Figure 10. Astrometric data for M 39 (NGC 7092). Proper motion (left), KDE of parallax values (centre) and equatorial position (right). Red dashed lines indicate 1, 2 sigma. Blue star with error bars indicates WD candidate.

Figure 11. Astrometric data for Stock 12. Proper motion (left), KDE of parallax values (centre) and equatorial position (right). Red dashed lines indicate 1, 2 sigma. Blue star indicates WD candidate.

The astrometric data for the WD in Stock 12 places all the parameters at just about the 2σ-level with respect to the mean cluster values. The Gaia CMD Gaia (Fig. 15) suggests a rather low mass for the WD with our best estimate being 0.47 M while the temperature from this photometry is about 18,000 K.

The spectroscopic values determined from the Gemini North spectrum are in strong disagreement with the photo- metric values for the mass and temperature. The measured spectroscopic value of log g is 8.50 with a temperature of about 31,600 K suggesting a much higher mass (0.94 M ) and hotter WD. Unlike the WDs in M 39 and ASCC 47, there is no obvious evidence of a magnetic field in the Stock 12 spectrum, so it does not appear that the lines have the excess broadening that could account for this higher log g value. This possibility cannot be entirely excluded however. In the Montreal WD database (Dufour et al. 2017) the star is listed as a DA WD (32,158 K, log g 8.30, 0.83 M ). These numbers come from analysis of an SDSS spectrum and are in reasonable agreement with our spectroscopic results except that our log g value, which we adopt, is larger. The Sloan colours for this WD ((u − g)0 = −0.21 and (g − r)0 = −0.38) also suggest a temperature (25,000 K) significantly cooler than the spectroscopic values. Perhaps the reddening has been underestimated. We will adopt the Gemini spectroscopic parameters for this WD in order to estimate its cooling time and precursor mass. The time for a 0.94 M WD to cool to its current observed temperature of 31,600 K is only ∼37 Myrs. Since we estimate the cluster age from the CMD Fig. 15 to be 300±50 Myrs, the main sequence lifetime of the progenitor was Massive White Dwarfs in Young Star Clusters 15

ASCC 47

Stock 12

ASCC 113

Stock 2

Relative Flux Alessi 21

vdb Hagen 23

M 39

3800 4000 4200 4400 4600 4800 5000 5200 5400 6400 6500 6600 6700 [Å] [Å]

1.2

1.0

0.8

0.6 Relative Flux M 47

0.4 4000 4500 5000 5500 6000 6500 [Å]

Figure 12. Spectra of the cluster WDs obtained with Gemini. The upper panels show the DA WDs ordered from the hottest (ASCC 47) to the coldest (M 39). The upper-right panel shows Hα for each of the spectra. The lower panel shows the only DB white dwarf found in this survey (M 47).

∼263 Myrs implying that the WD precursor was a star of mass 3.7±0.4 M . While not a particularly massive WD, this object is consistent with other objects in its location in the IFMR (Fig. 16).

6. CLUSTER WHITE DWARFS LOCATED FAR FROM THEIR BIRTHPLACE

In section4, we calculated the expected number of white dwarfs in each cluster, hNWDi. Although the error in hNWDi is large for some clusters, hNWDi in many clusters exceeds the observed number of WDs, providing evidence for a deficiency of observed WDs. Out of the 163 clusters for which we were able to fit isochrones, hNWDi > 1 for ∼ 65% of the clusters analyzed. This suggests that there may exist a widespread phenomena of missing WDs in many young, open clusters. This discrepancy is somewhat mitigated by the fact that, for the most distant clusters, we did not expect to detect the full population hNWDi of white dwarfs because the more massive are now cold and dim, below the detectability threshold for Gaia. Another potential factor is that WDs may be given a modest kick (a few km/sec) when born (Fellhauer et al. 2003). As a result, as the WDs age and move away from the center of the cluster, they may then often be found near or beyond the periphery of the cluster in positional space and hence be excluded when considering data 16 Richer et al.

ASCC 47 ASCC 113 Alessi 21 vdbH 23 M39 H-

H- 2

H-

Relative Flux H- 1

100 0 100 100 0 100 100 0 100 100 0 100 100 0 100 [Å] [Å] [Å] [Å] [Å]

Stock 12 Stock 2 H-

H- 2

H- Relative Flux H- 1

100 0 100 100 0 100 [Å] [Å]

Figure 13. Fit to the Balmer lines for the cluster WDs. This was used to obtain an estimate of the surface gravity and effective temperature for each WD. For the WDs in the upper panel, the Balmer lines Hβ to H were used in the fit, while for the WDs in the lower panel, the Balmer lines Hα to Hδ were used to determine the stellar parameters. In each panel the best fit is shown in red, while the values for the best fits are given in Table3. within a chosen radial distance. With even a kick of 1 km/sec, one of these WDs could travel around 100 pc away from the cluster in 100 Myr, making it imperative to consider potentially kicked WDs that we may have missed in our initial search. In order to explore this possibility further, we selected 40 of our surveyed clusters and searched within a wide radius for potential stripped WDs. This subset of clusters has WEBDA distances below 800 pc and ages between 10 Myr and 150 Myr (corresponding to turnoff masses of 14.5 M to 4.3 M ). For each cluster, a query was made to the Gentile Fusillo et al.(2018) catalog for high probability WD candidates (their Pwd ≥ 0.75) within 20× the literature cluster radius and 2σ in proper motion of the cluster centre, accounting for the WD proper motion error provided by Gaia. Using such a large search radius for these young clusters should allow us to capture most of the expelled WDs. After removing the objects that already appeared in our original narrow search, a total of 992 potential cluster member candidate WDs were identified in the 40 selected clusters. Massive White Dwarfs in Young Star Clusters 17

Figure 14. A four panel diagram showing the CMDs (increasing in age) for the clusters vdB Hagen 23, Alessi 21 ASCC 47 and Messier 47 (NGC 2422). DA WD cooling sequences (B´edard et al. 2020) for 0.8, 1.0 and 1.2 M are shown for all the clusters except M 47 which are DB sequences of the same mass as this WD is a known DB star (Richer et al. 2019). The WD does not appear as massive here as we claimed in (Richer 2019) as its has an IR-excess which is important in the Gaia filters and less so in the u, g VPHAS+ filters which we used in the previous paper. Isochrone ages are indicated in the diagram.

Candidate WDs were dereddened using associated cluster parameters, allowing their mass and cooling ages to be 4 estimated using the python package WD models . WD masses ≤ 1.0 M are modeled using the Montreal group CO 5 6 cooling models (B´edardet al. 2020) , while those > 1.0 M use O/Ne core models (Camisassa et al. 2019) , up to a maximum of 1.28 M . Progenitor masses were estimated for each WD using the IFMR from Cummings et al.(2018).

4 https://github.com/SihaoCheng/WD models 5 http://www.astro.umontreal.ca/∼bergeron/CoolingModels/ 6 http://evolgroup.fcaglp.unlp.edu.ar/TRACKS/ultramassive.html 18 Richer et al.

Figure 15. A four panel diagram showing the CMDs (increasing in age) for the clusters Stock 2, ASCC 113, Messier 39 (NGC 7092) and Stock 12. DA cooling sequences (B´edardet al. 2020) for 0.8, 1.0 and 1.2 M are included. Only the bluer and brighter WD candidate in Stock 2 is discussed here as the other star does not appear to be a likely cluster member given its potential mass. Isochrone ages are indicated in the diagram.

Fig. 16 shows the full set of candidate WDs, along with mass models for WD masses between 0.20 M and 1.28 M , for cooling ages between 10 Myr and 1 Gyr. To focus on the most likely cluster members, only WDs whose upper bound cooling age was younger than the cluster age plus the 1 σ error were retained (see Table5). Additionally, WDs whose progenitor mass +3 σ was less than the cluster main sequence turnoff were removed. This loose cutoff allowed us to remove some clear outliers without excluding candidates that may be reasonable given their location in the cluster CMD. There were a handful of objects with masses outside the model grid range (> 1.28 M ) for which we did not have cooling ages. For these candidates, their positions in the cluster CMDs were examined individually for candidacy. In the end, of the 992 WDs in the Massive White Dwarfs in Young Star Clusters 19

Table 2. Properties of New Massive Cluster White Dwarf Candidates

Cluster Name Cluster Age (Myrs) WD Mass (M ) Precursor Mass (M ) Comments vdB-Hagen 23 55±20 0.63±0.03 ...... unlikely cluster member Alessi 21 60±20 0.85±0.02 ...... unlikely cluster member ASCC 47 90±20 1.01±0.02 5.6±0.8 magnetic DA, hottest cluster WD known Alessi 8 100±30 ...... not a WD NGC 3114 130±25 ...... not a WD M 47 150±20 1.06±0.05 6.1±0.5 magnetic DB, IR excess Stock 2 225±50 0.99±0.03 5.5±1.5 cluster age uncertain ASCC 113 240±40 1.06±0.10 5.8±0.8 tied (M47) as most massive WD found in this survey M 39 280±20 0.95±0.02 5.4±0.6 magnetic DA Stock 12 300±50 0.94±0.02 3.7±0.4 magnetic DA?

Table 3. WD Parameters from the Spectroscopic Fits

Cluster Name log g [log(cm s−2)] Effective Temperature [K] Comments

vdB-Hagen 23 8.02±0.03 19,600±200 ...... Alessi 21 8.36±0.03 23,500±200 ...... log g affected by magnetic field, ASCC 47 8.93±0.13 114,000±3,000 photometric log g = 8.47 ± 0.05 (see Caiazzo et al. 2020) Stock 2 8.58±0.05 24,900±400 photometric temperature 29,000 K ASCC 113 8.71±0.07 25,400±300 ...... log g affected by magnetic field, M39 8.93±0.06 18,100±300 photometric log g = 8.54 ± 0.04 (see Caiazzo et al. 2020) Stock 12 8.50±0.04 31,600±200 estimate of log g could be affected by magnetic field

wide search, 151 of them were retained as possible cluster members. The candidates’ physical parameters are shown in Table4, along with the associated cluster and its WEBDA diameter. For additional cluster parameters see Table5. We stress that these additional 151 candidate WDs require significant follow-up, including spectroscopy and a detailed analysis of their proper motions, to better assess their candidacy and that they do not represent bona-fide cluster members. For these same 40 clusters, all the white dwarfs should still be visible in Gaia and the number of expected white dwarfs is hNWDi = 203 ± 39, which is within 2σ of the wide search survey results. Although this result is encouraging, we expect a large fraction of the candidates not to be cluster members. Further studies investigating the physical mechanism behind WD kicks or modelling cluster diffusion in detail could be key in determining where the majority of WDs in open clusters may be hiding. The results of the wide search will be examined in more detail in future work.

7. IMPLICATIONS OF THE SEARCH FOR MASSIVE CLUSTER WDS From the discussion in the previous sections, it is clear that we expected to find many more massive WDs than we ultimately located. As hinted at earlier, this may be a result of a kick imparted to the WD when born. Though the wide search potentially located some of these objects, further examination would be required to verify membership in their respective clusters. Even if all these WDs were bona-fide cluster members (which is surely not correct), many massive cluster WDs remain unaccounted for. In Fig. 17 we present a new version of the IFMR concentrating on the high mass end of the relationship. In this plot we only include those cluster WDs that appear in Gaia, pass all our astrometric tests for cluster membership and have an initial mass in excess of 2.5 M . A number of WDs that appeared in previous instances of this plot (e.g. Cummings et al. 2018) were eliminated from this diagram simply because they are too faint to be in Gaia (e.g. several WDs in NGC 2168, NGC 2323-WD10). Others did not pass all our astrometric tests (e.g. NGC 3532-J1107-584). The current diagram has much less scatter than earlier versions. Of interest is that we were not able to locate WD precursors in these clusters that were more massive than about 6 M . Except possibly for GD 50, there is no cluster WD known that passes strict astrometric tests and that evolved from a single main sequence star in excess of this 20 Richer et al.

Figure 16. Candidate cluster member WDs identified in the wide search. WDs in the CMD have been dereddened using their associated cluster values. Primarily vertical tracks show mass models from 0.20 M (far right) to 1.28 M (far left), while primarily horizontal ones show cooling ages from 10 Myr (top) to 1 Gyr (bottom). mass. In fact, since GD 50 is not really a bona-fide member of any well-defined stellar cluster (it may be part of the AB Doradus moving group) and considering that it may even be a merger remnant (Vennes et al. 1996), it was excluded from the current version of the IFMR. The most massive WD precursor remaining in Fig. 17 is the 6.1 M precursor to the magnetic DB in Messier 47. A mass of 6 M seems to be the upper limit to WD precursors that we found in the clusters that we surveyed here. This may be a fundamentally important result or it may be a consequence of massive WDs either quickly leaving their clusters after birth through some dynamical event or being undetectable due to being located in binary systems. We found that the upper limit of the initial stellar mass for white dwarf formation only has a modest effect of about 30% on the expected number of white dwarfs. On the other hand, the multiplicity fraction amongst high mass stars is thought to be substantial, even greater than 75% (for recent discussions see Kobulnicky & Fryer 2007; Moe & Di Stefano 2017); making this is an important consideration. If this low upper limit to WD formation is a result of stellar evolution and not a consequence of dynamics or binarity, it exacerbates the discrepancy between the observed SN II rate and the number of stars with masses in excess of that capable of producing such a SN. Horiuchi et al.(2011) suggested that a rate that was twice as high as observed would occur if all stars more massive than 8 M produce SN II. If this limit is reduced to 6 M this discrepancy becomes at least a factor of three. Additionally, it appears that single stars do not leave behind electron-degenerate remnants Massive White Dwarfs in Young Star Clusters 21 that even remotely approach the Chandrasekhar Limit — from our survey the highest mass WDs produced appear to be below 1.1 M .

Figure 17. IFMR for stars with initial masses in excess of ∼ 2.5 M including the new cluster WDs discovered in the current survey plus those from the literature which pass all our astrometric tests. The stars plotted as “Various” with black dots are NGC 3532-J1106-584, NGC 3532-J1106-590 and NGC 2516-5. Many of the stars appearing in earlier versions of this diagram are not present here as they did not pass our strict astrometric requirements or simply because they were too faint for Gaia. The Hyades WDs were not actually found in our survey because of the large angular extent of the cluster, but are included here nonetheless. 22 Richer et al.

APPENDIX

Table4 contains select parameters for clusters associated with wide search WDs, as well as a number of WD parameter estimates if they are indeed cluster members. We emphasize that this is not a list of WDs that are necessarily cluster members, instead is a list of WDs that could be part of these clusters and are worth considering in future work. Table5 contains information on the young open clusters that were searched for potential massive WDs in the narrow search. While WEBDA provided the source list for the majority of these clusters (with the exception of 6, as discussed in section 2), all the astrometric information contained in the table was derived by the authors using the Gaia DR2 database. Table6 contains a list of objects which appear in Cummings et al.(2018) as potential cluster member WDs but do not meet our search criteria, along with corresponding Gaia data, if available. Any objects that appear in this reference and make our cuts have already been listed in Table1.

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ACKNOWLEDGMENTS This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa. int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/ web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement.

Facilities: Gaia(DR2), Gemini North and South Software: Astropy (Astropy Collaboration et al. 2013, 2018), Cloudy (Ferland et al. 2013), SExtractor (Bertin & Arnouts 1996)

Table 4. Wide Search WD Cluster Member Candidates

Cluster WD

Name Diam. Turnoff Mass Gaia Source ID G0 (Bp-Rp)0 Dist. Mass Cooling Age

[pc] [M ] [mag] [Clrad][M ] [Myr]

Est. Upper Lower Est. Upper Lower

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13)

Alessi 5 4.76 5.00 5352954771936845440 11.02 -0.51 18.04 1.07 >1.28 0.81 55.48 . . . 89.14 Alessi 8 7.32 4.64 5887666586717940224 10.07 -0.48 16.18 0.69 0.93 0.53 10.55 3.14 18.92 5982381370178315904 9.95 -0.73 9.50 >1.28 >1.28 1.13 ...... 0.14 Alessi 12 9.45 4.64 1762939111272873216 11.08 -0.58 16.10 1.20 >1.28 1.06 6.55 . . . 68.19 1805484267034684672 10.98 -0.30 19.39 0.68 0.87 0.50 98.47 74.50 136.19 1817445136772265856 11.20 -0.27 6.22 0.72 0.95 0.50 142.19 101.40 198.14 1832754079548398848 11.22 -0.35 10.54 0.85 1.00 0.70 120.30 98.30 150.07 1840424272662732544 11.36 -0.20 16.57 0.67 0.94 0.46 203.37 136.24 290.33 1847749287845442176 11.21 -0.34 17.46 0.85 1.02 0.67 120.86 95.56 156.95 1862286485141695104 11.29 -0.43 14.03 1.01 1.17 0.82 108.81 50.06 143.76 1865111023126770560 10.68 -0.48 19.45 0.90 1.06 0.76 39.81 22.95 44.38 1865156034384396672 10.89 -0.55 19.35 1.10 1.25 0.97 18.12 0.17 58.36 Alessi 19 16.94 4.50 4376049337883929984 10.43 -0.40 17.70 0.64 0.92 0.44 27.70 18.68 56.15 4468178417905732864 10.78 -0.41 14.45 0.80 1.18 0.48 53.28 0.68 99.17 4470497631525396864 10.64 -0.35 10.21 0.64 0.98 0.39 49.12 32.76 103.30 4477802370166728192 10.13 -0.47 7.24 0.68 1.12 0.43 12.11 0.25 33.54 4480180961719293056 11.16 -0.25 4.28 0.66 1.08 0.36 143.71 69.92 268.44 4480191681947797632 11.01 -0.12 4.00 0.42 0.79 0.25 176.59 90.46 280.19 4480458519688606848 10.31 -0.33 3.15 0.49 0.76 0.31 35.59 16.04 96.42 4482142280001910400 10.63 -0.87 3.09 >1.28 >1.28 >1.28 ...... 4484494994368242944 10.74 -0.32 1.34 0.62 0.88 0.41 64.99 46.48 113.69 4486590599105841408 10.80 -0.39 14.05 0.76 1.06 0.51 58.71 35.23 94.01 4499995393896134400 10.82 -0.46 9.98 0.91 >1.28 0.59 53.48 . . . 81.83 4502033686597154560 10.62 -0.38 8.04 0.69 0.88 0.52 42.18 34.92 61.96 4507419403783827584 10.84 -0.30 10.25 0.62 1.00 0.35 82.25 50.79 173.90 4508142156589768448 10.87 -0.32 4.76 0.67 0.91 0.47 79.31 58.98 121.61 4508653399438645632 10.52 -0.57 4.83 1.07 >1.28 0.79 7.16 . . . 28.47 4510989208806897792 10.74 -0.39 10.80 0.74 >1.28 0.26 52.32 . . . 209.78 4527635157714872960 11.24 -0.36 11.90 0.88 1.08 0.66 120.64 78.70 167.26 4535822945927846528 10.73 -0.37 18.10 0.71 0.95 0.51 53.73 42.60 81.90 4537315605983651072 10.95 -0.43 20.25 0.90 1.14 0.66 69.10 10.99 96.18 4549137859941184256 10.53 -0.50 15.59 0.89 1.13 0.68 26.39 0.64 33.07 4549929821847911680 10.58 -0.41 16.56 0.72 0.99 0.51 35.17 25.39 57.45

Table 4 continued on next page Massive White Dwarfs in Young Star Clusters 25 Table 4 (continued)

Cluster WD

Name Diam. Turnoff Mass Gaia Source ID G0 (Bp-Rp)0 Dist. Mass Cooling Age

[pc] [M ] [mag] [Clrad][M ] [Myr]

Est. Upper Lower Est. Upper Lower

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13)

4551088943325443712 11.13 -0.33 12.71 0.80 0.98 0.62 112.27 88.04 147.45 4575935024190275328 10.53 -0.46 13.84 0.81 1.06 0.61 28.91 11.53 39.15 4576926710662025472 10.92 -0.27 14.98 0.60 0.77 0.46 100.42 76.99 137.91 4580243696729381888 10.93 -0.25 18.05 0.58 0.78 0.41 107.69 77.56 156.51 Alessi 21 10.03 5.50 2949405787932448384 11.16 -0.46 11.22 1.04 1.20 0.84 86.94 11.50 110.89 2951717579847688960 10.28 -0.63 18.55 1.18 >1.28 1.00 0.14 . . . 4.95 2953180617506290048 11.07 -0.31 10.96 0.74 1.03 0.48 108.61 75.60 168.00 3028302962770764416 11.23 -0.49 17.03 1.08 1.27 0.89 79.62 1.33 116.93 3033651678824971264 11.37 -0.47 12.00 1.08 1.26 0.90 103.91 13.29 145.36 3041793008368326784 10.99 -0.37 16.80 0.81 1.15 0.48 82.98 11.56 143.64 3045185929454409856 11.38 -0.54 6.26 1.17 >1.28 1.00 66.59 . . . 127.50 3047918903045538944 10.01 -0.57 1.91 0.91 1.08 0.75 2.78 0.34 7.34 3049634312983990272 11.20 -0.45 4.33 1.02 >1.28 0.69 94.28 . . . 148.66 3049898092693361792 10.96 -0.47 5.19 0.98 1.21 0.74 65.90 0.92 86.77 3050876554961550848 11.19 -0.57 6.37 1.20 >1.28 0.96 14.96 . . . 99.89 3052133335414358784 11.00 -0.37 4.80 0.81 1.07 0.56 83.94 47.89 125.61 3057432667921034752 11.05 -0.36 19.56 0.81 0.98 0.63 95.38 77.24 123.25 3058657901831394432 10.58 -0.45 12.06 0.80 1.05 0.60 32.78 18.17 44.64 3099313168902595840 10.93 -0.40 9.98 0.85 1.07 0.63 71.17 41.47 98.10 3102498320947143296 11.32 -0.68 12.89 >1.28 >1.28 0.95 ...... 124.89 3103735576466830208 11.18 -0.32 16.32 0.79 1.13 0.46 122.97 47.09 209.30 Alpha Per 20.40 5.81 408144424247559680 9.36 -0.61 4.77 0.92 >1.28 0.86 0.25 . . . 0.34 ASCC 113 9.37 3.47 1853507876918946432 11.04 -0.32 15.50 0.73 1.01 0.48 103.66 73.22 159.69 1854288087800311552 11.25 -0.22 13.13 0.65 0.82 0.51 172.22 134.56 215.47 1858474645820394240 11.28 -0.47 19.95 1.07 1.22 0.90 95.91 19.86 125.86 1866829323581231616 11.11 -0.43 10.75 0.96 1.16 0.75 86.39 26.02 115.41 1866921476396272256 11.22 -0.20 9.91 0.60 0.78 0.46 175.59 134.40 226.94 1867163472040641280 11.02 -0.24 8.21 0.58 0.84 0.39 125.11 84.63 191.35 1867327471071322240 10.10 -0.63 8.82 >1.28 >1.28 0.94 ...... 3.25 1870421359346313088 11.42 -0.17 15.49 0.65 0.90 0.46 227.16 157.65 311.00 1949768165721708544 11.57 -0.44 19.61 1.08 >1.28 0.86 140.33 . . . 216.22 1963968770715879680 11.51 -0.33 4.31 0.93 1.13 0.68 175.97 110.07 253.51 1965199570908941568 11.36 -0.30 2.60 0.83 1.14 0.50 159.50 77.12 262.13 2064173102208150912 11.27 -0.30 17.38 0.79 1.07 0.53 144.65 93.15 216.48 2064364623389656576 11.44 -0.20 14.27 0.71 0.99 0.49 218.18 144.12 311.61 2067097223322941184 11.12 -0.21 15.66 0.59 0.76 0.45 151.58 115.74 198.42 2067450024818993152 11.17 -0.32 20.00 0.80 1.09 0.50 119.60 63.95 188.70 2068194806504634240 11.17 -0.38 18.33 0.90 1.21 0.57 103.97 9.49 170.87 Collinder 121 23.14 7.94 2899802695231620992 10.60 -0.44 10.12 0.78 1.09 0.52 35.12 3.03 58.88 2921327769947744000 10.47 -0.54 3.04 0.99 >1.28 0.70 16.61 . . . 26.93 2924675400598744704 10.70 -0.49 5.85 0.94 1.21 0.69 40.16 0.28 51.74 3033651678824971264 10.36 -0.49 19.56 0.81 1.14 0.56 17.43 0.29 30.14 5584168976198163328 10.77 -0.41 9.69 0.79 1.16 0.48 52.55 0.90 95.60 5588351484074655232 10.36 -0.68 18.58 >1.28 >1.28 1.03 ...... 5.42 5608976535503258496 10.44 -0.50 6.37 0.86 >1.28 0.44 21.11 . . . 57.76 5609238734667240064 9.96 -0.73 8.24 >1.28 >1.28 1.09 ...... 0.24

Table 4 continued on next page 26 Richer et al. Table 4 (continued)

Cluster WD

Name Diam. Turnoff Mass Gaia Source ID G0 (Bp-Rp)0 Dist. Mass Cooling Age

[pc] [M ] [mag] [Clrad][M ] [Myr]

Est. Upper Lower Est. Upper Lower

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13)

5610515714344370560 10.31 -0.56 5.26 0.99 >1.28 0.66 6.34 . . . 19.63 5610628139404763904 10.60 -0.41 4.31 0.73 1.19 0.40 37.68 0.28 92.06 5611082753112158976 10.06 -0.49 5.06 0.70 1.07 0.49 9.78 0.55 22.39 5613411170843319168 9.53 -0.76 10.83 >1.28 >1.28 >1.28 ...... 5616150058598869248 10.70 -0.72 8.19 >1.28 >1.28 0.52 ...... 74.95 5616446858022119936 10.50 -0.58 7.63 1.08 >1.28 0.67 5.24 . . . 31.37 5717606115367003136 10.51 -0.46 18.60 0.80 1.12 0.54 27.46 0.68 45.75 Collinder 132 17.62 7.37 2892194903699687552 10.57 -0.45 18.10 0.80 1.20 0.49 32.27 0.24 60.55 2924675400598744704 11.14 -0.46 19.21 1.01 1.20 0.80 85.78 9.61 112.91 5511212943722649344 10.57 -0.40 19.99 0.70 1.06 0.43 36.22 13.69 77.32 5511542792916930048 10.79 -0.30 20.03 0.60 1.18 0.28 74.35 0.70 214.71 5546969680338155136 10.45 -0.56 19.63 1.04 >1.28 0.72 9.42 . . . 25.46 5559843823326236416 10.62 -0.48 19.26 0.88 >1.28 0.54 34.70 . . . 58.93 5559937350535040384 10.64 -0.43 18.11 0.79 1.09 0.54 38.92 7.93 61.81 5584168976198163328 11.20 -0.37 11.61 0.90 1.17 0.59 110.92 35.35 173.20 5584360119422916736 10.58 -0.41 11.76 0.71 1.13 0.40 35.74 0.79 85.47 5588351484074655232 10.79 -0.64 6.60 >1.28 >1.28 1.05 ...... 39.18 5589923235942686848 10.68 -0.59 6.25 1.15 >1.28 0.87 0.71 . . . 39.91 5595074928959659136 10.63 -0.47 8.08 0.87 >1.28 0.57 35.69 . . . 55.97 5597663797814959488 11.10 -0.47 14.92 1.02 >1.28 0.61 80.10 . . . 138.66 5597782441987499520 10.60 -0.54 12.41 1.02 >1.28 0.71 23.77 . . . 38.05 5604794508666591232 10.91 -0.37 1.04 0.77 1.18 0.43 74.58 2.02 145.95 5605936450274462208 9.78 -0.57 3.43 0.84 1.08 0.65 2.46 0.23 7.21 5606544450148104576 10.87 -0.49 3.81 0.98 >1.28 0.69 54.91 . . . 76.05 5608976535503258496 10.88 -0.46 10.45 0.94 >1.28 0.53 58.63 . . . 105.08 5609238734667240064 10.39 -0.69 5.47 >1.28 >1.28 1.08 ...... 2.74 5610515714344370560 10.74 -0.52 8.05 1.02 >1.28 0.75 38.25 . . . 52.28 5611516884103827328 10.03 -0.51 3.62 0.74 1.04 0.54 8.16 0.63 16.41 5613261190584162048 10.36 -0.58 7.52 1.06 >1.28 0.73 3.80 . . . 19.67 5614341602495158144 10.43 -0.57 12.26 1.05 >1.28 0.59 6.70 . . . 32.05 5618530084662423808 10.33 -0.52 11.58 0.87 1.09 0.69 14.21 1.45 19.13 5644308826265337600 10.90 -0.39 19.92 0.82 1.10 0.54 69.27 18.04 107.95 5697651426736462592 11.23 -0.38 18.07 0.91 1.21 0.58 113.96 16.22 185.37 5710639373476492032 10.85 -0.55 14.30 1.09 >1.28 0.81 16.11 . . . 61.74 IC 2391 2.66 7.01 5317454079808243456 11.19 -0.50 4.73 1.08 1.16 1.01 71.72 36.65 93.01 NGC 2422 3.51 4.05 3028302962770764416 11.51 -0.54 7.17 1.19 >1.28 1.05 80.04 . . . 141.78 3028924221197888768 11.78 -0.41 10.09 1.10 >1.28 0.87 186.51 . . . 297.74 3028937037380440448 11.41 -0.37 9.43 0.97 1.10 0.79 142.38 100.77 185.62 3029069940849870720 11.59 -0.35 5.43 0.99 1.17 0.76 181.28 115.45 257.71 3030482160458326784 11.47 -0.22 7.82 0.74 1.00 0.53 218.32 149.11 305.02 3030544832620996224 11.62 -0.31 12.43 0.94 1.09 0.75 204.09 146.06 270.58 3031106030224132608 11.85 -0.46 16.85 1.17 >1.28 1.01 181.18 . . . 265.69 3033489943235297280 11.80 -0.35 12.45 1.06 1.26 0.79 221.09 93.50 343.38 3033552443600454784 11.65 -0.39 15.02 1.06 1.23 0.85 172.65 85.80 250.48 3039980222933652096 11.74 -0.30 16.81 0.97 1.15 0.74 238.22 158.18 337.64 NGC 2451B 11.61 6.25 5428728474760340352 11.97 -0.62 20.18 >1.28 >1.28 1.21 ...... 191.38

Table 4 continued on next page Massive White Dwarfs in Young Star Clusters 27 Table 4 (continued)

Cluster WD

Name Diam. Turnoff Mass Gaia Source ID G0 (Bp-Rp)0 Dist. Mass Cooling Age

[pc] [M ] [mag] [Clrad][M ] [Myr]

Est. Upper Lower Est. Upper Lower

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13)

5532546561683429888 12.06 -0.66 5.81 >1.28 >1.28 1.18 ...... 236.79 5534595188067100032 11.36 -0.55 4.92 1.19 >1.28 1.05 52.67 . . . 113.83 5551243031058471808 11.68 -0.62 18.19 >1.28 >1.28 1.13 ...... 150.11 5575674041987286400 11.93 -0.63 13.00 >1.28 >1.28 1.12 ...... 223.55 5591693965064811776 11.53 -0.57 5.66 1.24 >1.28 1.09 49.38 . . . 131.09 5609107476168766848 11.45 -0.72 15.74 >1.28 >1.28 >1.28 ...... 5610083052220844800 11.69 -0.51 14.04 1.20 >1.28 1.07 122.13 . . . 176.88 5616906690102297600 11.34 -0.48 15.95 1.08 1.18 1.00 95.11 52.19 118.99 5694411367829835136 11.40 -0.50 15.54 1.12 1.23 1.05 89.61 34.10 121.00 NGC 2516 3.63 3.68 5276965113864595200 11.35 -0.37 18.39 0.94 1.04 0.83 134.49 116.51 156.50 5289447182180342016 11.23 -0.24 5.94 0.68 0.82 0.56 158.61 129.12 193.08 5290719287073728128 11.13 -0.30 0.72 0.73 0.85 0.62 122.89 103.82 146.34 5290834387897642624 10.89 -0.35 1.21 0.73 0.87 0.60 75.76 63.63 93.87 5294015515555860608 11.18 -0.42 5.92 0.96 1.11 0.78 96.54 55.12 123.77 5294686526884585600 11.92 -0.28 11.52 1.01 1.15 0.81 295.28 207.13 403.04 NGC 5662 6.53 4.64 5879516284965902720 9.72 -0.49 18.81 0.57 0.98 0.38 9.09 0.52 25.42 NGC 6025 3.27 4.57 5829676281875471616 10.07 -0.71 17.65 >1.28 >1.28 0.85 ...... 5.71 5832578511570131200 10.49 -0.54 14.82 0.99 >1.28 0.36 17.71 . . . 92.64 NGC 7063 1.76 4.67 1963968770715879680 11.00 -0.40 17.41 0.87 1.15 0.58 78.65 11.45 121.65 Pismis 4 5.05 4.37 5329969103416108032 10.99 -0.31 11.71 0.70 0.98 0.47 97.66 69.90 151.42 5331602526709717760 10.88 -0.36 18.30 0.74 1.05 0.48 73.41 47.24 122.13 5525116852370580864 11.00 -0.38 13.72 0.83 1.18 0.49 82.20 5.70 143.64 Pleiades 4.76 4.20 66697547870378368 10.74 -0.53 1.53 1.03 1.06 1.00 37.52 29.21 40.65 vdB Hagen 164 6.33 7.94 5795934499101239552 10.55 -0.53 13.22 0.98 1.17 0.80 24.05 0.35 30.79 5823612299144570368 10.54 -0.72 9.71 >1.28 >1.28 >1.28 ...... 5823613334236349568 11.09 -0.52 9.49 1.09 >1.28 0.90 52.41 . . . 88.91

Notes. Selected parameters for those clusters associated with wide search WDs. Also included are WD parameter estimates assuming they are cluster members. Columns: (1) cluster name; (2) diameter (from WEBDA); (3) current cluster main sequence turnoff mass (using IFMR from Cummings et al.(2018)); (4) Gaia DR2 WD source ID (Gaia Collaboration et al. 2018); (5) WD absolute G magnitude (using associated cluster distance and reddening and AG = 2.059E(Bp − Rp) , see Table.5); (6) intrinsic ( Bp − Rp) color (similarly dereddened); (7) distance from cluster center in units of cluster radius; (8) mass estimate WD from cooling model fits; (9-10) 1σ upper and lower bound estimates on WD mass; (11) WD cooling age estimate from model fits; (12-13) 1σ upper and lower bound estimates on cooling age. 28 Richer et al. 7 5 1 1 5 2 . 7 7 7 6 68 4 . . 97 63 . . . 93 ...... 1 5 . 1 . 2 . 32 . . 3 3 3 1 0 0 1 0 1 . 0 0 0 1 10 2 ± 0 ± ± ± ± ± ± ± WD ± ± ± ± ± ± ± ± ± ± 6 5 2 3 72 5 ...... σ N Rp) Expected − Mean (Bp E red N ] π [ π σ ] δ µ [ σ δ µ ] α µ [ σ α . Clusters studied µ continued on next page ] δ [ Table 5 Table 5 δ σ ] α Position Proper Motion Parallax [ α σ 2.572 0.674 58.742 0.385 8.186 0.388 -2.43 0.444 2.3 0.287 27 0.566 0.082 0 53.06 1.033 44.862 0.885 0.921 0.24495.02 0.64 -2.999 46.716 0.248 0.561 1.116 1.1 0.188 204 0.322 0.23 0.008 -0.648 23 0.227 1.556 0.15 91 0.141 0.013 7 221.96 0.253 -66.43 0.133 -7.552 0.248 -10.301 0.288 2.326 0.345 37 0.193 0.034 0 52.331 1.447 48.586 1.162 22.65772.42478.636 0.696 1.169 1.936 41.797 -26.014 44.817 0.611 1.825 1.191 -0.577 -0.465 5.729 0.252 0.219 0.131 94 -2.778 -1.736 0.158 0.237 0.01 0.133 0.994 0 0.136 0.912 0.161 121 104 0.31 0.324 0.012 0.018 4 0 13.211 1.68251.905 61.55 1.411 0.88 35.016 1.207 2.777 -1.659 0.303 0.22 -0.934 -1.348 0.292 0.232 1.073 0.594 1.464 56 0.184 0.415 61 0.037 0.306 10.4 0.013 7 109.117 0.664160.802 -46.554 0.885 0.604 -61.109 0.649265.908 -9.876 -15.344 0.217 -46.944 0.617 0.469 0.225 11.883 9.844 2.573 0.601 0.178 0.437 3.559 0.205 2.201 -8.948 1.694 31 0.072 55 0.098 4.792 0.021 0.256 0.512 0.014 8.8 29 1.6 0.07 0.019 2 232.624 1.402 -51.271 0.982 -5.914 0.165 -5.689 0.163 1.479 0.152 62 0.149 0.022 1.6 310.949 0.753 23.799275.248 2.065 0.703 11.923 4.354 1.997 -1.015 0.218 0.158 -4.645 -7.001 0.184 1.848 0.158 0.445 1.545 125 0.276 0.098 12 0.008 0.115 2.8 0.059 0.54 116.711 0.26 0.094 0.28 0.716 0.346 -4.004 0.331 3.35 0.171 29 0.031 0.01 1 107.686 0.699 -9.406 0.659 -5.492 0.211 2.568 0.214 1.74 0.153 104 0.1 0.011 1.4 118.261 0.848 -53.058 0.785 -5.367 0.213 8.892 0.225 1.39 0.15 68 0.219 0.016 8.4 † † ‡ ‡ † ‡ ‡ † † † † † † ‡ ‡ ‡ † ‡ 30 40 90 50 100 20 10 135 4 25 117 45 15 112 20 100 126 102 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± Age [Myr] [deg] [deg] [deg] [deg] [mas/yr] [mas/yr] [mas/yr] [mas/yr] [mas] [mas] [mag] [mag] stars N Cluster Alessi 3Alessi 5Alessi 6Alessi 40 8Alessi 92 9 600 71 192 80 30 - 100 281 ASCC 4ASCC 6 202 300 ------Alessi 12Alessi 13Alessi 19 182Alessi 20 - 100 56 81 110 - 9 ------Alessi 21 176 60 ASCC 11ASCC 12ASCC 13 569ASCC 18 293ASCC 246 19 448ASCC 20 93 ASCC - 21 32 ASCC - 23ASCC - 26ASCC - 28 - 181ASCC 29 -ASCC 234 - 30 -ASCC - 31 -ASCC - - 32ASCC - - 33 -ASCC - - 34 - -ASCC - - 35 - -ASCC - 36 - -ASCC - - 38 - - -ASCC - - 40 - -ASCC - - 41 ------44 ------214 ------ASCC 10 152 263 ASCC 42 124 400 Alpha-Per 133 51 Massive White Dwarfs in Young Star Clusters 29 6 7 3 2 . . . . 5 1 0 1 ± ± ± ± ∗ WD σ N Rp) Expected − Mean (Bp E red N ] π [ π σ ] δ µ [ σ δ µ ] α µ [ σ (continued) α µ continued on next page Table 5 ] δ [ Table 5 δ σ ] α Position Proper Motion Parallax [ α σ 128.15 1.243 -39.355 1.157 -8.1 0.226 5.6 0.238 1.272 0.14 94 0.136 0.015 4.7 282.18 0.432 -18.724 0.46 4.994 0.153 -1.522 0.183 3.188 0.315 12 0.242 0.039 180.634 0.899 -60.895 0.665 -6.626 0.156 1.617 0.159 0.957 0.207 216 0.279 0.009 23.2 131.624 0.743131.908 -38.048 0.855 -42.407 0.61 0.792 -8.49 -12.344 0.336 0.198 6.501 3.631 0.323 0.206 2.258 1.49 0.14 0.14 161 47 0.102 0.225 0.01 0.032 0 0 288.346 0.316294.087 0.373 36.376 35.768 0.308 0.347 1.005 -0.701 0.319 0.421 1.347 -2.366 0.304 0.417 2.507 0.138 2 30 0.16 0.068 62 0.016 0.084 4.0 0.01 3.5 † † † † † † 50 20 90 10 20 10 ∗ ± ± ± ± ± ± Age [Myr] [deg] [deg] [deg] [deg] [mas/yr] [mas/yr] [mas/yr] [mas/yr] [mas] [mas] [mag] [mag] stars N Cluster ASCC 50ASCC 51ASCC 56 257ASCC 58ASCC - 59 30 ASCC - 60ASCC - 66ASCC - 68 - - - - - 582 - - 200 ------ASCC 43ASCC 44ASCC 46ASCC - 47ASCC - 49 - 171 - 78 90 - - 20 - - - -ASCC 69 -ASCC 71 -ASCC 72 -ASCC - 73 -ASCC - 74 -ASCC - - 76ASCC - - 81 -ASCC - - 82 - -ASCC - 83 - -ASCC - 84 - -ASCC - - 85 -ASCC - - - 86 -ASCC - - - 87 - -ASCC - - - 89 - -ASCC - - 91 - - -ASCC - - 96 - - - -ASCC - - 97 - - - -ASCC - - 98 - - - -ASCC - - - 99 ------21 ------ASCC 100ASCC 101ASCC 103 -ASCC 104 49ASCC 105 93ASCC 106 420 - - 230 ------30 Richer et al. 1 8 1 3 69 . . . . . 1 2 2 60 59 0.90 . 2 3 0 . . 1 ± ± 0 0 ± ∗ ∗ ∗ ∗ ∗ ∗ WD ± ± ± ± ± ± 2 6 . . σ N Rp) Expected − Mean (Bp E red N ] π [ π σ ] δ µ [ σ δ µ ] α µ [ σ (continued) α µ continued on next page Table 5 ] δ [ Table 5 δ σ ] α Position Proper Motion Parallax [ α σ 0.964 0.824 -29.945 0.839 18.7 0.524 2.648 0.51 4.202 0.387 161 0.038 0.005 3 97.83197.642 0.334 0.253 9.948 2.895 0.398 0.232 -2.256 -2.294 0.372 0.228 -5.187 -0.566 0.376 0.216 1.398 0.282 0.57 35 0.346 0.752 11 0.094 0.576 0.127 0 131.205 0.157 -41.28 0.131 -5.717 0.35 4.119 0.299 1.033 0.195 34 1.321 0.049 109.344 1.102111.179 -36.909 1.074 1.054 -32.284 1.026 -10.061 -8.026 0.402 0.559 6.236 4.785 0.361 0.461 3.314 0.332 2.529 88 0.485 0.066 53 0.011 0.064 0.018 0 0 112.861 0.333 -17.104 0.395 -2.984 0.201 1.875 0.199 0.776 0.151125.824 72 0.145 0.138 -36.34 0.02 0.131 11.6 -4.969 0.234 3.897 0.289 0.532 0.332 38 0.348 0.023 104.056 1.358110.685 -24.256 2.49 1.42 -31.341 2.633 -2.81 -3.859 0.231 0.236 3.405 3.665 0.232 0.238 1.119 1.321 0.218 0.267 313 52 0.125 0.011 0.089 0.016 0 0 297.167 0.275 21.974 0.262317.989 0.732 -0.174 38.638329.321 0.572 0.675 0.156 51.554 0.787 -5.136 0.42341.959 0.22 -0.542 0.903 0.15 46.322 0.115 -3.696 1.102 0.728349.906 0.162 1.503 -0.553 0.23 0.32 21 54.541 0.951 0.112 1.751 0.77 0.211 0.142 1.216 0.054 1.305 155 0.123 -1.577 0 287.838 0.078 0.226 26 0.107 0.006 0.205 13.109 0.36 0.17 13.3 1.373 0.106 0.026 0.168 0.037 4.17 0.225 103 0.243259.345 1.453 0.231 0.173 0.262 0.01 -35.51 -3.194 75 11.6 0.15 0.22 0.2 -0.296 0.014 0.663 7 0.207 0.321 9 -1.29 1.207 0.241 0.067 0.559 0.352 16 1.099 0.062 292.136 0.106 17.358 0.108 -1.904 0.14 -5.421 0.148 0.398 0.133 31 0.902 0.06 † ‡ ‡ † † † ‡ † ‡ † † ‡ 50 50 8 40 30 13 15 12 10 10 100 120 ∗ ∗ ∗ ∗ ∗ ∗ ± ± ± ± ± ± ± ± ± ± ± ± Age [Myr] [deg] [deg] [deg] [deg] [mas/yr] [mas/yr] [mas/yr] [mas/yr] [mas] [mas] [mag] [mag] stars N Basel 8 ------Cluster Basel 14 ------Blanco 1 250 105 Bochum 5 161 350 ASCC 107ASCC 109ASCC 112 74ASCC 113 -ASCC 114 17 -ASCC 115 234ASCC 117 -ASCC 240 118 - 51ASCC 123 - -ASCC 124 200 -ASCC 126 - - -ASCC 127 192 -ASCC 128 - 300 ------213 - - 251 ------Biurakan 2 ------Bochum 13 120 Berkeley 86Berkeley 87 ------Berkeley 59Berkeley 82 - 62 ------Berkeley 47 80 Collinder 65Collinder 69Collinder 89 -Collinder 95 -Collinder 96 -Collinder 97 134 - 59 20 ------Collinder 135Collinder 140 149 119 26 Collinder 197 35 102 Collinder 173Collinder 185 - 105 ------Collinder 132 237 25 Collinder 121 973 20 Aveni-Hunter 1 ------Massive White Dwarfs in Young Star Clusters 31 7 . 6 . 17 07 2 12 . . 0 0 ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ WD ± ± ± ± 6 8 . . σ N Rp) Expected − Mean (Bp E red N ] π [ π σ ] δ µ [ σ δ µ ] α µ [ σ (continued) α µ continued on next page Table 5 ] δ [ Table 5 δ σ ] α Position Proper Motion Parallax [ α σ 26.788274.14 1.61 0.107 71.728 -18.31538.235 0.6 0.107 0.148 58.766 0.08 -1.734 0.117 0.282 0.467 0.205 -0.268 -1.657 0.21 0.296 0.243 -0.753 0.984 0.39 0.405 0.195 0.174 199 0.324 17 0.248 0.5 0.99 9 0.01 0.081 1.062 0.081 137.64 0.552 -53.863 0.417 -5.979 0.16 5.671 0.157 0.905 0.15 54 0.242 0.013 5 168.25 0.151 -60.781 0.114 -6.124 0.229 1.037 0.226 0.319 0.196 57 0.777 0.029 56.132 0.136 32.165 0.134 4.308 0.851 -6.722 0.775 3.108 0.336 10 1.359 0.035 0 202.495 0.258 -64.181 0.135267.039 0.544 -5.705 1.404 0.153 0.479 -4.968 -1.575 0.296 0.149 0.21 -0.064 0.276 0.284 54 2.679 0.723 0.213 0.034 37 0.458 0.025 129.169 1.306 -52.558141.873 1.211 0.269 -56.996 -23.981 0.177 1.101 -7.75 23.49 0.223 1.297 5.68 6.57 0.189 0.24 10 0.73 0.103 0.108 0.052 201 0 0.345 0.007 22 218.473 0.128251.661 -61.333 0.118 0.109 -47.083 0.107 -5.213 -0.725 0.152 0.171 -2.443 -1.971 0.175 0.195 0.377 0.159 0.349 0.172 10 12 0.223 0.192 0.896 0.045 ‡ ‡ ‡ ‡ 95 78 6 14 ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ± ± ± ± Age [Myr] [deg] [deg] [deg] [deg] [mas/yr] [mas/yr] [mas/yr] [mas/yr] [mas] [mas] [mag] [mag] stars N IC 361 ------IC 348 29 12 Hogg 3 ------Hyades ------Cluster IC 2395IC 2488 - 397 162 ------IC 2391 14 29 IC 2602IC 4665 ------Hogg 12 305 Hogg 14Hogg 17Hogg 22Hogg 23 - 75 76 ------Czernik 8 167 Coma Ber ------Haffner 13Haffner 26 ------Dolidze 42 ------Feinstein 1 ------ESO 123-26ESO 166-04 - 164 200 ------ESO 175-06ESO 332-08ESO 429-13 ------Collinder 236Collinder 258Collinder 271 -Collinder 285 -Collinder 306 338Collinder 350 - -Collinder 351 - -Collinder 359 66 Collinder 367 - -Collinder 394 - - -Collinder 399 - -Collinder 463 - -Collinder - 469 - - - 850 - - - 120 ------32 Richer et al. 0 5 1 . 7 2 7 . 5 2 1 3 . 54 ...... 6 1 4 4 34 86 2 4 2 12 2 26 . . 37 ± ± ± 0 0 ± ± ± ∗ ∗ WD ± ± ± ± ± 6 ± ± 2 1 1 9 . . . . . σ N Rp) Expected − Mean (Bp E red N ] π [ π σ ] δ µ [ σ δ µ ] α µ [ σ (continued) α µ continued on next page Table 5 ] δ [ Table 5 δ σ ] α Position Proper Motion Parallax [ α σ 9.872 0.134 61.097 0.111 0.357 0.215 -3.265 0.205 0.772 0.114 10 0.727 0.071 18 40.69 0.374 61.608 0.276 -1.729 0.228 2.094 0.257 0.877 0.123 135 0.497 0.01 22 22.39 0.155 63.3 0.112 -4.262 0.165 0.254 0.18 0.32 0.122 58 0.804 0.036 62.476 0.164 49.504 0.133 1.307 0.224 -3.652 0.216 0.645 0.116 59 0.99 0.03 43.1 10.991 0.43 61.81740.518 0.19852.939 0.539 -5.31357.318 0.255 42.71261.961 0.199 37.374 0.46 0.23 0.153 52.659 0.21 0.732 62.328 0.118 -0.114 0.546 0.115 -0.72 0.287 -0.562 0.21 0.254 0.375 -5.705 0.323 1.434 -1.609 0.128 -1.809 0.336 -0.812 0.253 32 1.95 0.35 0.304 1.504 0.391 0.179 0.022 0.13 0.857 306 0.908 0.168 0.198 127 5 0.132 13 0.006 0.434 41 0.017 0.963 10 1.127 0.081 37.7 0.05 0 0 159.289 0.521 -59.099 0.424 -14.454 0.37 1.065 0.397 2.195 0.147 97 0.16 0.015 0.55 322.977 0.826130.079 0.545 48.296 19.657 0.701 0.539 -7.554 -36.141 0.406 1.072 -19.73 -12.843 0.421 0.935 3.356 5.327 0.137 0.39 65 174 0.044 0.119 0.008 0.009 8 27.8 114.162 0.381 -14.495 0.382 -7.064 0.277 0.958 0.25 2.072 0.222 291 0.149 0.006 16.5 216.082 0.223253.748 -61.333 0.111 0.129 -45.238 0.105 -6.648 -0.355 0.27 0.27 -4.618 -1.926 0.312 0.248 1.037 0.149 0.336 0.243 58 32 0.39 0.958 0.013 0.047 3 ‡ † ‡ † ‡ † ‡ ‡ ‡ † † ‡ ‡ 20 49 93 63 50 5 5 30 190 100 190 100 138 ∗ ∗ ± ± ± ± ± ± ± ± ± ± ± ± ± Age [Myr] [deg] [deg] [deg] [deg] [mas/yr] [mas/yr] [mas/yr] [mas/yr] [mas] [mas] [mag] [mag] stars N M39M44M47 85 220 398 407 600 150 King 6 162 * 51.995 0.192 56.439 0.141 3.863 0.194 -1.825 0.208 1.338 0.128 49 0.724 0.015 * Cluster IC 4725IC 5146 ------Loden 1 ------Lynga 2 111 102 Mayer 1 ------Loden 59Loden 89 ------Lynga 14 76 NGC 133NGC 189 - 50 398 ------NGC 225NGC 559 69 524 288 Loden 143 127 50 Loden 189Loden 309Loden 565Loden - 682Loden - 807 ------NGC 1027NGC 1039NGC 1342 433NGC 1444 434NGC 195 1502 293NGC 132 1513 61 600 136 361 10 11 200 Melotte 20 ------Mamajek 2 ------Loden 1010Loden 1171Loden 1194 -Loden 2326 ------Melotte 111Melotte 227 ------Johansson 1 ------Markarian 38 ------Massive White Dwarfs in Young Star Clusters 33 1 7 9 5 0 2 8 ...... 7 4 8 8 0 6 3 6 3 . 6 . . . . 6 ...... 1 4.9 7.7 . 9 9 1 4 9 52 73 48 . 12 11 14 17 2 11 179 1 10 2 4 5 1 . . 9 . 1 ± ± ± ± 0 0 0 ± ± ± ± ∗ ∗ WD ± ± ± ± ± ± ± ± ± ± ± ± ± ± 3 ± ± ± 1 3 7 0 7 6 6 2 0 5 4 ...... σ N Rp) Expected − Mean (Bp E red N ] π [ π σ ] δ µ [ σ δ µ ] α µ [ σ (continued) α µ continued on next page Table 5 ] δ [ Table 5 δ σ ] α Position Proper Motion Parallax [ α σ 93.01 0.168 5.453 0.163 0.437 0.177 -1.976 0.173 0.413 0.358 96 0.405 0.019 21 65.19371.479 0.41772.134 0.397 50.23 19.102 0.38 0.355 0.353 10.888 -1.964 -1.002 0.37677.036 0.204 -1.101 0.197 0.375 37.021 -0.112 0.247 -1.492 0.169 0.199 -1.925 0.534 0.316 1.356 0.247 1.677 0.235 0.134 0.162 2.403 64 -3.124 181 0.141 0.45 0.566 55 0.235 0.011 0.014 0.397 0.574 24.1 3 0.014 0.118 18.1 98 0.493 0.016 20 63.888 0.321 51.213 0.235 2.165 0.217 -2.232 0.209 0.95 0.129 139 0.412 0.011 35 75.945 0.426 23.69 0.4 -0.941 0.34988.076 -2.378 0.19 32.545 0.301 0.176 1.348 1.931 0.174 178 0.237 0.466 -5.638 0.01 28 0.223 0.667 0.117 715 0.374 0.005 327 76.174 0.144 23.814 0.136 3.136 0.22592.261 -3.468 0.471 24.326 0.193 0.464 1.1 2.276 0.124 82 0.285 0.469 -2.914 0.015 31.2 0.284 0.441 0.626 776 0.29 0.005 92.122 0.191 13.953 0.179 -0.944 0.612 -1.602 0.501 1.006 0.212 35 0.321 0.057 0 92.557 1.038 -3.343 0.891 -0.605 0.234 -0.291 0.242 1.347 0.247 17 0.252 0.036 5 98.085 0.483 4.875 0.445 -1.581 0.369 0.155 0.363 0.648 0.122 104 0.917 0.04 96.906 0.664 -4.793 0.667 -4.681 0.299 -1.799 0.306 3.06 0.321 59 0.146 0.026 0 107.02 0.13 -10.623 0.123 0.216 0.28 -0.189 0.207 0.909 0.127 107 0.262 0.013 3 119.51 0.901 -60.782 0.595 -4.661 0.619 11.127 0.558 2.406 0.143 719 0.089 0.004 34.6 116.11 0.608 -24.754 0.613 -3.299 0.232 2.945 0.216 0.831 0.205 209 0.104 0.01 7 102.079 0.482 41.041 0.457 -2.954 0.297 -8.316 0.266 1.886 0.146 207 0.153 0.01 28 101.495 0.468 -20.705102.978 0.478 0.14 -4.333 -7.088 0.14 0.224 -1.439 -1.357 0.296 0.246 -0.247 1.356 0.191 0.252 423 0.807 0.039 0.175 0.003 24 75 0.195 0.017 8.7 102.949 0.223 0.47 0.206 -1.337 0.253 -2.178 0.233 1.14 0.13 350 0.092 0.004 25 105.706 0.191106.696 0.133 -8.349 -10.023 0.191 0.129 -0.704 -0.767 0.466 0.229 -0.624 -0.647 0.391 0.217 0.992 0.582 0.146 0.119 378 63 0.306 0.007 0.531 0.027 26 17.8 109.676 0.125 -24.951112.018 0.135 0.485 -11.708 -2.762 0.466 0.263 -1.509 2.934 0.158 -0.239 0.266 0.749 0.149 0.143 0.669 77 0.071 0.17 165 0.029 0.132 0.009 4 0 114.825 0.246 -16.512 0.27 -3.228 0.265 2.439 0.209 0.746 0.122 151 0.134 0.01 47.6 116.155 0.682 -37.903 0.651 -9.529 0.554 4.788 0.458 2.708 0.294 73 0.189 0.021 0 115.824 0.906 -38.383 0.782 -21.053 0.73 15.328 0.71 5.157 0.218 52 0.036 0.016 0 ‡ ‡ ‡ ‡ ‡ ‡ † ‡ ‡ † † ‡ † ‡ † ‡ † ‡ ‡ ‡ ‡ ‡ ‡ ‡ ‡ ‡ 85 6 8 81 50 63 50 53 50 50 50 60 141 123 213 308 120 294 102 42 3 35 100 46 20 17 ∗ ∗ ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± Age [Myr] [deg] [deg] [deg] [deg] [mas/yr] [mas/yr] [mas/yr] [mas/yr] [mas] [mas] [mag] [mag] stars N Cluster NGC 1528NGC 1545NGC 1647 339NGC 1662 143 295 NGC 1746 476NGC 110 1750 113 200 -NGC 650 1778 360NGC 1802 257 NGC 1960 292NGC 1976 - -NGC 178 1977 376NGC 1981 -NGC 2099 - - - * - 1488 - 447 - 84.081 - - 0.144 - 34.137 - - 0.133 - - -0.135 - - - - 0.234 - - - - -3.37 - - - 0.211 - - - 0.659 - 0.437 - - 164 - - - 0.39 - 0.014 - - - - * ------NGC 1758 169 600 NGC 2168NGC 2169NGC 2184 1600 133 158 12 646 NGC 2186 256 251 NGC 2232NGC 2244NGC 2281 142 394 18 313 617 NGC 2287NGC 2301NGC 2302 649 536 170 162 214 250 NGC 2323NGC 2335 795 207 132 200 NGC 2343 174 87 NGC 2353NGC 2362 - 223 6 ------NGC 2368NGC 2396 - 388 72 ------NGC 2413NGC 2430 - 308 600 ------NGC 2448 474NGC 2467NGC 2516 95 - 1073 200 ------NGC 2451B 118 41 NGC 2451A 73 35 34 Richer et al. 1 7 5 2 9 6 8 . . . . 3 3 8 9 3 0 6 9 8 2 . . . 3 ...... 62 . 2 4 3 3 3 5.2 6 8 8 9 . 2 33 73 118 . . . . . 12 10 18 4 1 2 16 5 4 4 3 8 1 . . 0 1 1 2 2 1 ± ± 0 0 ± ± ± ± ± ∗ ∗ ∗ ∗ ∗ ∗ WD ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 3 7 9 ± ± 7 3 5 9 3 6 7 7 4 4 5 9 ...... σ N Rp) Expected − Mean (Bp E red N ] π [ π σ ] δ µ [ σ δ µ ] α µ [ σ (continued) α µ continued on next page Table 5 ] δ [ Table 5 δ σ ] α Position Proper Motion Parallax [ α σ 243.3 0.171 -54.228 0.133 -1.924 0.146 -2.588 0.143 0.433 0.161 329 0.517 0.009 123.11 0.907 -37.584 0.778 -3.742 0.212 3.865 0.225 0.962 0.243 256 0.219 0.009 19 122.48 0.508 -49.191 0.48 -8.507 0.277 4.332 0.341 2.544 0.198 88 0.195 0.026 0 253.56 0.14 -41.83 0.141 -0.562 0.255 -2.156 0.243 0.589 0.11 157 0.692 0.023 248.66 0.141 -49.774250.33 0.119 0.167 -48.783 -0.698 0.131 0.273 1.309 -2.806 0.474 0.261 -3.937 0.66 0.37 0.116 127 0.8 1.253 0.146 0.022 56 1.081 0.05 0 190.573 0.122195.047 -62.996 0.326 0.104 -59.601208.547 0.235 0.448211.885 -4.879 -61.896 0.629218.764 -8.112 -48.307 0.219 0.27 0.614222.201 -56.644 0.208 0.169 0.5 -6.291 -1.023 0.461 -54.508 -1.193 0.131 -6.588 -6.425 0.196 0.206 -2.751 0.204 0.247 0.254 0.658 -1.533 0.133 0.264 0.795 -3.444 -7.179 0.113 0.208 42 -3.07251.539 85 0.252 0.675 0.469 0.257 0.113 0.083 0.02 0.53 1.287 -47.023 0.274 1.292 247 0.239 0.106 0.012 0.129 0.919 0.427 133 19.8 157 -0.703 2.6 0.203 0.008 0.165 0.384 28 29 0.009 0.223 0.009 0.462 9 7.8 -0.565 0.019 2.1 0.198 0.806 0.116 50 0.611 0.017 5 121.261 0.223 -28.156 0.176123.378 -5.571 0.4 -5.738 0.214131.643 0.379 0.533131.381 7.296 -52.929 0.157143.324 -1.334 0.437 -48.799 0.276 0.135 -53.418 0.21 0.211150.577 -4.073 0.218 0.561 -5.378 1.541 -60.046 0.226 0.988156.633 -8.51 0.121 0.197 0.37 0.112 97 4.592 0.206 -60.675164.879 0.263 -7.332 0.104 3.621 0.265 0.096 1.287 0.223 -60.334 -5.888 0.013 5.352 0.133 0.279 0.175 0.179 40 0.904 289 0.173 -7.397 0.188 0.253 3.789 0.635 0.045 157 0.19 0.004 1.286 3.325 0.142 0.258 0.323 38 0.168 78 0.008 0.948 70 0.162 2.684 0.588 0.127 12 0.021 0.082 0.146 666 0.145 0.145 0.01 6 0.134 0.348 31 0.004 3 0.183 0.621 38.2 160 0.038 0.74 0.02 301 124.727 0.127 -29.768 0.131 -4.916 0.249155.301 4.233 0.17159.675 -51.758 0.134 0.26 0.135 -54.134 -14.765 0.734 0.116 0.139 0.524 -7.697 84 -0.681 0.192 0.246 0.018 0.431 2.992 0 2.01 0.187 0.292 0.547 10 0.167 0.098 57 0.024 0.224 0 0.019 2 187.469 0.129 -64.796 0.107206.626 0.131 -5.327 -62.916 0.108 0.197 -4.663 -0.348240.786 0.174 0.516 0.214 -60.44244.708 -2.367 0.239246.466 0.354 0.53 -57.932 1.018 0.104 -2.907 0.182 0.163 -40.476248.937 28 0.61 0.113 0.625 -1.559 0.195 0.714 -45.646 0.114 -0.21 0.105 0.017 0.227 -3.042 63253.885 0.552 0 0.248 0.38 -2.388 0.185 0.123254.439 0.017 -39.466 0.107254.466 0.195 1.247 -2.002 0.247 0.124 -44.817 0.134255.182 0.184 0 0.104 -45.949 0.386 1.017 -3.35 1.142 0.252 170 0.116 -44.661 0.248 1.736 0.244 1.658 0.322 102 0.212 0.407 0.19 0.009 0.355 -1.026 0.292 0.24 106 7 1.102 -0.844 0.012 0.2 0.161 0.671 0.201 -3.452 5 0.209 0.038 8 -2.386 -2.886 17 0.166 0.77 0.339 0.127 0.211 0.792 0.22 0.035 0.159 148 0.39 0.956 0.526 16 0.308 0.191 0 0.01 0.665 342 27 0.053 8 1.058 0.527 0.71 0.014 0.035 0 165.602 2.896186.015 -58.506 0.135 -58.126 1.53 0.109 -10.349 -8.836 0.446 0.135 5.123 1.484 0.438 0.13 1.967 0.45 0.361 0.125 205 0.061 68 0.006 0.423 19 0.023 ‡ ‡ † ‡ ‡ ‡ ‡ † † ‡ ‡ ‡ ‡ † ‡ ‡ ‡ ‡ ‡ ‡ ‡ ‡ ‡ ‡ ‡ ‡ † ‡ † ‡ 50 79 76 10 20 68 65 49 62 25 50 48 91 6 39 330 16 186 13 15 39 100 14 19 190 45 3 37 45 12 ∗ ∗ ∗ ∗ ∗ ∗ ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± Age [Myr] [deg] [deg] [deg] [deg] [mas/yr] [mas/yr] [mas/yr] [mas/yr] [mas] [mas] [mag] [mag] stars N Cluster NGC 2527NGC 2546NGC 2547 139NGC 2548 689 692 NGC 2571 153NGC 141 2579 442NGC 2669 32 160 389 NGC 2670 -NGC 2925 27 521NGC 3033 224NGC 135 3114 128NGC 102 3228 - 62NGC 129 3255 990NGC 3330 16NGC 130 3496 196 * - 135 30 966 147.147 81 - 350 0.119 -56.424 0.108 - -7.592 - 0.174 4.261 - 0.169 0.531 - 0.127 18 0.365 - 0.044 * ------NGC 3532 306 398 NGC 4609NGC 4852 102NGC 5316 304NGC 5460 81 NGC 200 5662 560NGC 5749 321 166 286 159 72 100 100 NGC 6204NGC 6231 134 516 93 NGC 4337NGC 4463 293 127NGC 5281 29 111 40 NGC 6025NGC 6067NGC 6087 322NGC 6124 965 NGC 105 6167 221NGC 6178 524NGC 100 6193 621 191 18 162NGC 6242 12 NGC 6249 5 NGC 6250 322NGC 6259 42 78 75 2396 55 24 Massive White Dwarfs in Young Star Clusters 35 2 9 0 7 2 1 4 . . . . 8 4 3 ...... 1 4.0 8.2 9 7 6 ∗ 27 66 41 . 13 16 2 17 1 17 . . . 3 13 0 0 0 ± ± ± ± ± ± ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ WD ± ± ± ± ± ± ± 1 3 3 ± ± ± 9 4 2 6 8 ...... σ N Rp) Expected − Mean (Bp E red N ] π [ π σ ] δ µ [ σ δ µ ] α µ [ σ (continued) α µ continued on next page Table 5 ] δ [ Table 5 δ σ ] α Position Proper Motion Parallax [ α σ 316.81 0.16 50.863 0.123 -1.213 0.174 -4.216 0.194 0.669 0.333 37 0.602 0.108 333.77 0.366 49.839 0.253 0.41 0.264 -2.817 0.25 1.118 0.129 164 0.28 0.009 11 266.007 0.301 -32.357 0.296268.538 0.871269.103 -1.936 -34.847 0.502 0.748 -18.825 0.177 0.437 2.963 -2.317 0.259 0.851 0.162 0.226 -5.268 0.923276.855 0.115 0.265 -1.802 0.772 156 6.554 0.234 0.387 3.405 0.246 0.011 1.361 0.8 1.11 0.161 24 519 144 0.123 0.497 0.477 0.005 0.013 -1.755 33 35 314.134 0.48 0.178 44.625 2.529 0.143 0.246 -4.317 62 0.244 0.23 0.018 31 -6.848 0.253 1.131 0.12 66 0.808 0.025 42 271.047 0.132 -22.507 0.13 0.394 0.359282.828 -1.361 0.132283.588 0.225 10.319 0.303 -19.891 0.132 0.81 0.23 1.398 0.187 -1.485 92 0.201 0.214 0.666 -3.514 0.048 -6.017 0.196 0.225 0 0.92 1.406 0.116 0.152 112 93 0.401 0.23 0.01 0.01 12 3 255.528 0.131256.178 -39.708 0.173 -37.942 0.12 0.165 0.928 -1.861 0.198 0.261266.722 0.18 -0.773 -4.009 -31.513 0.169 0.18 0.274 3.818 0.635 1.881271.111 0.128 0.144 0.122 0.18 -24.373 151 48 0.117274.988 0.229 0.558 -1.655 0.107 1.282 0.01 0.028 -17.092 0.201 16.3 0.106278.356 0.31 0.977 0.116 -0.545 0.255280.555 -10.4 -2.028 0.212 0.107 82 0.117 -6.207 0.295 0.376 -0.855 -0.007286.944 0.109 0.015 0.753 0.125 -0.336 0.123 0.212 0.227305.805 4.243 23.9 25 0.131 0.636305.934 0.208 0.133 -0.052 0.108 0.139 40.772 0.391 -0.758 38.506 0.121 -2.337 0.019 16 0.227 0.131 -3.399 0.561 0.234 0.469 0.208 -3.391 0.023 0.203 0.213 -3.502 0.256 211 0.203 0.182 0.912 -5.363 0.222 12 0.024 -5.777 0.356 0.982 0.23 0.172 0.212 0.079 0.537 52 0.555 0.161 1.156 0.105 40 0.03 22 1.315 1.198 0.036 0.066 259.624 0.113263.666 -42.938 0.144 0.106 -32.572265.085 0.127 0.362 0.112 -32.231 2.583 0.3 0.22 0.314 -1.324 -2.287 -1.635 0.303 0.211 0.298 -5.764 0.735 0.892 0.134 0.164 0.326 7 55 2.164 0.861 0.296 0.621 0.116 221 0.058 0.285 0 0.009 0 0 317.651 0.167320.431 0.514 45.629321.106 0.191 50.809 0.137322.177 0.489 36.487 0.463322.634 -0.342 47.102 0.166 0.16 7.47 0.425 0.209 51.599 1.544343.583 -0.295 0.125 0.253 0.116 -2.536 0.225 -1.649 60.813 0.207 0.205 0.104 2.9 -2.466 0.21 -1.123 1.298 -2.766 0.199 0.143 0.279 0.196 -1.63 0.217 1.489 9 2.724 0.729 0.282 0.118 0.206 -1.622 0.094 0.34 51 66 226 0.586 0.096 0.249 0.155 0.113 0.104 0.381 0.02 0.282 0.017 0.009 87 0 0.123 21.0 1 0 1.017 142 0.023 1.039 46.0 0.014 264.401 0.11 -35.018 0.107 -0.445 0.232 -2.046 0.206 0.349 0.127 9 0.914 0.073 328.444 0.163 62.593 0.118 -3.437 0.216 -1.28 0.234 1.059 0.147 19 0.568 0.064 0 ‡ ‡ ‡ ‡ ‡ † ‡ † ‡ ‡ ‡ ‡ ‡ ‡ † ‡ † ‡ ‡ 6 91 6 6 50 40 71 7 109 107 182 330 47 308 100 2 17 20 47 ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± Age [Myr] [deg] [deg] [deg] [deg] [mas/yr] [mas/yr] [mas/yr] [mas/yr] [mas] [mas] [mag] [mag] stars N Cluster NGC 744 124 * 29.663 0.159 55.469 0.121 -1.871 0.211 -1.738 0.186 0.73 0.108 62 0.41 0.018 * NGC 6268NGC 6281 151 208 300 NGC 6416NGC 6425NGC 6469 240NGC 6475 159 229 NGC 6494 -NGC 6514 624NGC 6530 293 224 NGC 6531 380 -NGC 6546 - 64 NGC 6613 323NGC 6618 -NGC 6633 - 12 54 -NGC 6649NGC 6664 95NGC 6683 - 564 - -NGC 6709 692 -NGC 6716 126 -NGC - 6755 176 - -NGC 6828 143NGC 191 6910 - 417 -NGC - - 6913 98 - -NGC 6997 137 NGC 7031 119 - - - - - 216 - 149 646 ------NGC 6322NGC 6383NGC 6396 43NGC 6405 184 99 12 356 4 35 NGC 7039NGC 7058NGC 7063 32NGC 7082 87NGC 7086 77 12 516 41 NGC 7243 576 98 NGC 150 7419 140 310 242 148 NGC 7160 49 15 36 Richer et al. 0 8 0 . 1 . 1 . 51 . . . 3 6 2 55 05 2.1 . 2 19 19 0 0.98 0.78 . . 2 ± 0 0 ± ± ± ∗ ∗ ∗ ∗ ∗ ∗ ∗ WD ± ± ± ± ± ± 3 ± ± 4 2 . . . σ N Rp) Expected − Mean (Bp E red N ] π [ π σ ] δ µ [ σ δ µ ] α µ [ σ (continued) α µ continued on next page Table 5 ] δ [ Table 5 δ σ ] α Position Proper Motion Parallax [ α σ 56.61 1.479 24.13 1.467 19.919 1.365 -45.428 1.482 7.341 0.218 413 0.096 0.005 10.1 76.926 2.246 22.034 2.418 0.168 0.331 -6.472 0.398 2.96 0.416 17 0.425 0.046 0.32 334.51 0.685 63.161 0.472 -2.338 0.227 -2.22 0.227 0.997 0.2 23 0.989 0.064 0 141.07 0.126 -51.659 0.111 -6.529 0.24 3.632 0.224 0.462 0.195 10 0.649 0.062 351.195 0.371 61.587 0.266 -1.95 0.213 -1.1 0.209 0.644 0.157 219 0.936 0.017 20.3 128.719 0.627 -44.431 0.535 -8.2 0.203 5.331 0.213 1.439 0.266 84 0.09 0.011 3 357.479 0.322129.413 68.03 0.106 0.21 -39.583229.187 0.105 0.156243.557 1.464 -59.658 0.115 -5.469 0.114 -51.863 0.225 0.105 0.556 -4.152 3.997 -3.816 4.268 0.202 0.343 0.217 -3.743 0.551 0.999 -4.295 0.117 1.02 0.201 0.214 0.271 82 0.307 12 0.187 0.905 0.143 0.152 0.017 0.951 60 0.178 12 0.797 0.035 1.032 0 299.685 0.079 0.107 20.495307.234 0.865 0.106 39.514 -0.388 0.865 0.172 5.933 -5.119 0.304 0.192 2.164 0.582 0.214 0.287 20 2.821 0.127 0.435 0.016 81 0.057 0.007 5.4 313.437 0.702 38.082 0.68 1.723 0.146 -0.371 0.157 0.793 0.098 57 0.452 0.021 6.7 111.157 0.155114.261 -26.226 0.433 0.145 -15.621 0.445 -0.509 -3.179 0.221128.938 0.211 0.889 1.141 -44.403161.912 0.592 0.103 0.457 0.238 -57.477 -8.197 0.334 0.223 0.352 0.351 -11.18 0.132 0.678 0.452 55 5.327 0.181 105 0.844 0.206 0.029 0.295 2.428 0.013 31 1.401 0.191 0 0.14 0.928 81 0.115 0.077 161 0.008 0.129 3.6 0.008 10 114.396 0.528 -26.488 0.498 -1.229 0.15166.057 0.175 0.444 -61.377 0.121 0.153 -6.431 0.386 0.28 0.178 116 3.087 0.26 0.028 0.194 0.376 0.243 112 0.444 0.021 † ‡ † † ‡ † ‡ † † ‡ ‡ ‡ 25 58 5 50 30 62 20 66 50 20 4 15 ∗ ∗ ∗ ∗ ∗ ∗ ∗ ± ± ± ± ± ± ± ± ± ± ± ± Age [Myr] [deg] [deg] [deg] [deg] [mas/yr] [mas/yr] [mas/yr] [mas/yr] [mas] [mas] [mag] [mag] stars N Cluster Pleiades 483 135 Pismis 4Pismis 5Pismis 8 137 31 120 61 10 * 130.406 0.107 -46.269 0.104 -5.698 0.244 4.926 0.197 0.521 0.1 9 1.011 0.093 * Platais 1Platais 2Platais 3Platais 4 -Platais 5 -Platais 6 -Platais 25 8 -Platais 9 - - 70 ------Pismis 22 41 Pismis 21 198 Platais 10Platais 11Platais 12 ------Roslund 1Roslund 3Roslund 5Roslund - 6 71 - 103 - 250 ------Roslund 7 147 130 NGC 7654 1587 60 NGC 7762 431 Ruprecht 12Ruprecht 18Ruprecht 26 -Ruprecht 27 564Ruprecht 31 323 129 Ruprecht 59 834 32 Ruprecht - 64 -Ruprecht 65 -Ruprecht 76 -Ruprecht 91 126 -Ruprecht - 93 77 120 - 229 - 285 - 138 ------Ruprecht 107Ruprecht 113 132 - * - 199.941 0.119 -64.95 - 0.104 -5.837 - 0.218 -1.591 - 0.206 - 0.228 0.173 22 - 0.641 0.047 - * ------Pismis-Moreno 1 98 9 Massive White Dwarfs in Young Star Clusters 37 8 8 9 58 17 . . . 01 1 98 0 30 ...... 9 3 2 1 43 1.0 10.7 1.3 . 0 0 7 1 0 2 0 . 1 0 ± ± ± ± ± ± ± ± ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ WD ± ± ± ± ± ± 2 ± . 81 64 68 45 . . . . σ N Rp) Expected − Mean (Bp E red N ] π [ π σ ] δ µ [ σ δ µ ] α µ [ σ (continued) α µ continued on next page Table 5 ] δ [ Table 5 δ σ ] α Position Proper Motion Parallax [ α σ 264.46 0.117 -36.309 0.11 -0.294 0.203 -2.265 0.229 0.386 0.223 20 0.966 0.067 33.84731.127 1.087 0.697 59.547 64.369 0.689 0.443 15.857 -0.726 0.59 0.2 -13.705 -2.027 0.58 2.643 0.202 0.16 1.024 348 0.153 0.378 28 0.009 0.69 31.3 0.029 6.3 84.802 0.376 37.838 0.355 -3.163 0.39 -0.487 0.329 2.76 0.172 42 0.205 0.018 0 49.252 0.952 60.176 0.651 -4.258 0.193 -0.917 0.216 1.605 0.154 37 0.398 0.021 1.75 48.025 0.883 63.204 0.626 -3.349 0.288 -0.1 0.292 1.442 0.152 166 0.405123.44 0.008 0.438 0 -36.297 0.445 -7.143 0.37 7.327 0.303 2.217 0.18 13 0.108 0.026 0.23 167.85 0.13 -60.654 0.109 -7.139 0.177 0.588 0.159 0.632 0.116 33 0.416 0.015 0 264.08 0.113 -33.503 0.109 -0.155 0.247 -1.25 0.224 0.394 0.13 68 0.984 0.037 246.164 0.122 -51.942 0.108 -3.114 0.197 -4.328 0.189 0.325 0.305 20 0.66 0.036 282.685 0.685 -18.965 1.101 8.235 0.517 -3.906 0.516 1.644 0.164 34 0.334 0.025 10 289.106 0.475 -16.342 0.467 -0.924 0.498353.939 -26.599 0.785 52.684 0.526 0.526 3.242 8.551 0.188 61 0.26 0.202 0.016 -1.841 0.231 2.261 0.124 81 0.14 0.012 6.7 283.583 0.312 36.91 0.312 1.101 0.212 -2.98 0.237 2.778 0.189 40 0.128 0.02 0 269.172 0.167 -35.292 0.153 1.185 0.287128.662 0.879 -2.198 -44.405 0.537 0.321 -8.086 0.709 0.113 0.308 76 0.522 5.41 0.017 47.9 0.297 1.413 0.168 100 0.1 0.011 4.1 111.845 0.134131.896 -23.953 0.775 0.126 -42.46 -2.485 0.675 -12.371 0.223 0.369 3.328 6.501 0.237 0.336 0.577 0.175 2.262 0.243 89 136 0.386 0.103 0.012 0.011133.508 4.8 1.157 0 -43.361 0.822 -12.688 0.732 6.463 0.517 2.294 0.199 42 0.05 0.017 0 151.131 0.121 -55.395 0.106 -6.317 0.215 2.656 0.211 0.42 0.141 15 0.862 0.054 265.321 0.453 -40.162280.726 0.332 0.109 -4.158 0.481 0.11 0.157 -0.981 -2.296 0.269132.394 0.126 0.15 -2.244 -44.363 0.622 0.111 0.268 0.148 -4.794 162 0.325 0.183 0.425 0.221 0.015 16 5.238 0.533 0.102 0.229 0.41 0.147 11 1.258 0.069 203.044 0.125 -62.786 0.104 -4.681 0.184 -2.302 0.179 0.728 0.107 40 0.345 0.015 0 264.236 0.112 -32.479 0.111 -0.821 0.261 -2.773 0.276 0.71 0.141 16 1.037 0.053 ‡ † † † † † ‡ ‡ † ‡ † ‡ † † ‡ ‡ 50 20 50 30 388 14 39 30 22 20 16 100 20 15 23 24 ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± Age [Myr] [deg] [deg] [deg] [deg] [mas/yr] [mas/yr] [mas/yr] [mas/yr] [mas] [mas] [mag] [mag] stars N Cluster Stock 2Stock 5Stock 7 606 137 225 - 150 ------Stock 12 112 300 Stock 10 59 81 Stock 20Stock 23 - 60 90 ------Turner 2Turner 5Turner 9 ------Trumpler 2Trumpler 3Trumpler 6 -Trumpler 7 320 - 47 254 - 80 ------Trumpler 10 226 32 Trumpler 30Trumpler 37 192 200 ------Trumpler 18Trumpler 21 74 63 48 Trumpler 29 49 Trumpler 35 412 106 Trumpler 24Trumpler 27Trumpler 28 154 64 ------Stephenson 1 58 28 Ruprecht 118Ruprecht 119Ruprecht 103 127 156 127 * 247.046 0.14 -51.501 0.117 -1.336 0.17 -3.414 0.167 0.42 0.239 23 0.881 0.034 * Ruprecht 144Ruprecht 145Ruprecht 147 -Ruprecht 161 62 100 813 ------vdB-Hagen 23vdB-Hagen 34 32 164vdB-Hagen 56 55 120 vdB-Hagen 76 91 35 ------vdB-Hagen 87 174 vdB-Hagen 54 61 38 Richer et al. ∗ ∗ WD σ N Rp) Expected − is similarly Mean (Bp WD E N red N ] π [ 059E(Bp-Rp) ( Bressan et al. . = 2 G π σ A ] δ µ [ σ δ µ ] α µ [ σ (continued) α µ 771E(Bp-Rp) or to G-band extinction using . indicates manual age determination from this work, and * indicates that no age ‡ Table 5 ] δ [ δ σ ] α Position Proper Motion Parallax [ α σ 159.483 0.625186.747 -59.161 0.189222.211 0.435 -64.062 1.139259.074 -66.399 -14.438 0.12 0.107 0.586 -40.821 -6.212 0.393 0.106 -7.388 -0.676 0.147 1.015 0.476 0.255 -0.174 0.419 -10.517 -1.805 2.195 0.145 0.599 0.147 0.322 0.211 2.207 139 0.221 0.775 0.326 0.15 18 86 0.22 0.012 0.819 0.229 33 0.047 0.02 0.737 0 0.045 0 † † 20 10 ∗ ∗ ± ± Age [Myr] [deg] [deg] [deg] [deg] [mas/yr] [mas/yr] [mas/yr] [mas/yr] [mas] [mas] [mag] [mag] denotes an age from Cantat-Gaudin et al. ( 2020 ), † stars N determination was possible using our methods. In cases where we could not effectively determine an age estimate expected undetermined. Convert E(Bp-Rp) to E(B-V) using E(B-V) = 0 2012 ), but see also ( Casagrande & VandenBerg ). 2018 Notes. Cluster vdB-H 221vdB-H 245 ------vdB-Hagen 99 178 40 vdB-Hagen 132vdB-Hagen 164 153 vdB-Hagen 217 235 132 20 Massive White Dwarfs in Young Star Clusters 39

Table 6. WDs appearing in Cummings et al.(2018) but not meeting narrow search criteria

Name Gaia Source ID Parallax Pmra Pmdec Gobs (Bp - Rp)obs Comments [mas] [mas/yr] [mas/yr] [mag]

GD50 3251244858154433536 32.037±0.060 84.429±0.110 -162.959±0.088 14.035±0.001 -0.555±0.007 Not in search [1] Hyeggr29 45980377978968064 19.940±0.093 111.454±0.268 -22.021±0.146 15.378±0.001 -0.158±0.005 Not identified [2] Hyeggr316 3308403897837092992 21.732±0.056 95.276±0.110 -20.687±0.051 14.932±0.001 -0.196±0.005 Not identified [2] Hygd52 218783542413339648 23.558±0.046 145.993±0.098 -77.695±0.067 15.202±0.001 -0.104±0.003 Not identified [2] Hygd74 958262527212954752 17.189±0.063 -10.587±0.085 -114.047±0.078 15.000±0.001 -0.226±0.008 Not identified [2] Hygd77 966561537900256512 24.857±0.044 -16.619±0.072 -170.643±0.064 14.845±0.001 -0.100±0.006 Not identified [2] Hyhg7-85 39305036729495936 24.053±0.054 141.190±0.107 -24.070±0.084 15.039±0.001 -0.128±0.003 Not identified [2] Hyhz14 3294248609046258048 20.247±0.051 91.354±0.094 -10.643±0.050 13.864±0.001 -0.439±0.007 Not identified [2] Hyhz4 3302846072717868416 28.589±0.054 173.272±0.107 -5.510±0.079 14.564±0.001 -0.134±0.003 Not identified [2] Hyhz7 3306722607119077120 21.140±0.062 99.022±0.124 -14.314±0.071 14.263±0.001 -0.315±0.005 Not identified [2] Hylawd18 3313606340183243136 22.227±0.052 114.412±0.103 -27.715±0.079 14.347±0.001 -0.286±0.004 Not identified [2] Hylawd19 3313714023603261568 20.895±0.057 102.692±0.115 -26.885±0.068 14.075±0.001 -0.376±0.007 Not identified [2] NGC1039-15 340173367032619008 - - - 19.958±0.009 -0.304±0.222 Incomplete data NGC1039-17 337155723012394752 1.281±1.527 1.922±1.459 -1.251±2.584 20.081±0.008 -0.263±0.119 Potential member [3] NGC1039-S2 337044088221827456 - - - 19.388±0.005 -0.402±0.053 Incomplete data NGC2168-LAWDS1 ------Not in Gaia NGC2168-LAWDS11 ------Not in Gaia NGC2168-LAWDS12 ------Not in Gaia NGC2168-LAWDS14 ------Not in Gaia NGC2168-LAWDS15 ------Not in Gaia NGC2168-LAWDS2 ------Not in Gaia NGC2168-LAWDS22 3426288857352638080 0.783±0.694 0.561±1.652 -3.176±1.234 19.703±0.006 0.110±0.111 Potential member [3] NGC2168-LAWDS29 3426285249576179328 - - - 20.799±0.020 -0.525±0.229 Incomplete data NGC2168-LAWDS30 ------Not in Gaia DR2 NGC2168-LAWDS5 3426295183834581376 - - - 20.114±0.009 -0.199±0.109 Incomplete data NGC2168-LAWDS6 3426294977676135168 1.220±0.613 0.557±2.067 -4.744±1.867 19.923±0.009 -0.125±0.100 Potential member [3] NGC2287-2 2927203353930175232 -0.322±1.542 -6.526±1.644 -2.598±1.627 20.538±0.008 -0.134±0.140 Unclear [4] NGC2287-4 2927020766282196992 - - - 20.998±0.014 -0.032±0.213 Incomplete data NGC2287-5 2926996577021773696 -0.487±1.283 -4.177±1.328 -1.371±1.687 20.626±0.009 -0.231±0.111 Unclear [4] NGC2323-WD10 3051559974457298304 - - - 20.754±0.018 0.347±0.482 Incomplete data NGC2323-WD11 3051568873629418624 1.147±2.282 1.216±2.186 0.608±2.539 20.800±0.018 -0.089±0.122 Potential member [3] NGC2516-1 5290720455304928512 2.345±0.036 -4.825±0.082 10.905±0.071 8.984±0.001 0.178±0.001 Unlikely WD [5] NGC2516-2 5290718737318003840 2.306±0.045 -4.590±0.100 12.487±0.081 8.759±0.001 0.151±0.001 Unlikely WD [5] NGC2516-3 5290719287073728128 1.719±0.369 -5.245±0.729 11.171±0.648 19.407±0.004 -0.207±0.062 Potential member [3] NGC3532-1 5338680946400660480 1.900±0.038 -10.229±0.063 5.521±0.060 9.275±0.001 0.080±0.001 Unlikely WD [5] NGC3532-5 ------Not in Gaia NGC3532-9 5338702455587674368 0.641±1.395 -26.573±2.213 4.477±2.223 9.142±0.001 0.120±0.002 Unlikely WD [5] NGC3532-J1107-584 5340148691289324416 1.508±0.822 -11.383±1.306 2.192±1.349 20.235±0.010 -0.387±0.365 Potential member [3] PG0136+251 292454841560140032 12.524±0.116 52.872±0.185 -51.216±0.131 15.945±0.004 -0.532±0.017 Unlikely member prlb8648 660178942032517760 5.340±0.213 -39.308±0.372 -11.449±0.276 18.254±0.002 -0.079±0.019 Potential member [3] VPHASJ1103-5837 5338711045522811776 - - - 20.680±0.015 - Incomplete data

Notes. [1] GD50 is not expected to be part of any cluster included in the narrow search. [2] The Hyades was not identified in proper motion space using our methodology as it has such a large angular extent on the sky. The 11 WDs in this cluster were still included in the IFMR as extensive data has established cluster membership, e.g. see Salaris & Bedin(2018). [3] Do not pass cuts in proper motion and parallax, but with such large errors in the astrometry, we cannot preclude membership. [4] Negative parallax leads to uncertain cluster member candidacy. [5] Appear to be evolving off the main sequence and do not look to be WDs at all.