Retired a Stars and Their Companions IV. Seven Jovian

arXiv:1003.3445v1 [astro-ph.EP] 17 Mar 2010 aa ta.(08 eetdasnl lntszdobject planet-sized axis single semimajor a a detected with (2008) al. et Kalas ao ietn ihtefis ietiaigdetec- stars direct-imaging sequence main first around systems the planetary of with tions milestone major yasse ftresbtla bet ihsemimajor with objects substellar orbited three is Fo- of 8799 axes HR star system star A4V a dwarf young A5V nearby, by young the The around malhaut. belt dust the of omn ohhs-tr r -yedaf ihstellar in with dwarfs characteristics A-type of are masses host-stars number Both a common. share systems markable r ue-uieswt masses with super-Jupiters are dylresmmjrae rnigfo 20 from unexpect- (ranging with axes stars semimajor central large their edly from far orbit panions hr xssn rprmto olwu ftefitojc i object Simi faint 2008). the al. proper (Lafrenière 2009a). of et by J160929.1-210524 follow-up al. confirmed motion 1RXS et around proper been Lagrange no yet 2009; exists not al. there has et (2009b) (Fitzgerald al. motion et Lagrange by onAhrJohnson Asher John tt nvriy 50Jh .MritBv. o 9501, Box 06511 16802 PA Blvd., Park, University University, Merritt State nia A. John 37209 3500 TN Nashville, University, State 94720 CA Berkeley, 3411, Code 96822 HI Honolulu, Drive, lawn 91125 CA Pasadena, California. 249-17, of MC be University ogy, has the time and Keck NASA Calif Technology. both of of by University Institute granted the California by the jointly and operated is which vatory, [email protected] 8 h edo xpaeaysinercnl ece a reached recently science exoplanetary of field The rpittpstuigL using 2018 typeset 26, Preprint September version Draft h lntcniaeaon h -yestar A-type the around candidate planet The 7 6 5 4 3 2 1 a eateto srnm,Yl nvriy e ae,CT Haven, New University, Yale Astronomy, of Pennsylva- Department The Astrophysics, & Tennessee Astronomy of Systems, Department Information in Excellence Mail of California, of Center University Astronomy, of Wood- Department 2680 Hawai’i, of University Astronomy, for Institute Techn of Institute California Astrophysics, of Department ae nosrain banda h ..Kc Obser- Keck W.M. the at obtained observations on Based = > opnos hs rns oehrwt h ihpae assa masses im direct planet for high targets promising the trend headings: very with are f linear Subject stars sensitive long-term, together A-type a of trends, that is evidence indicate These planets show of systems st companions. migration planetary dwarf and around mon the formation planets disc of Our of the far properties that thus targets. the planets suggests from the interpreta the different of of very the characteristics are five strengthening orbital for further The observatory variability. stable, Fairborn photometrically at be APT m 0.4 M 1 metallicities ris h otsashv assrnigfo 1 from ranging planet– masses with have consistent stars velocities host radial The their orbits. in variability show stars { 1 erpr rcs ope esrmnso ee ugat from subgiants seven of measurements Doppler precise report We 24 . M 5 Jup , 38 ⊙ n aesmmjraxes semimajor have and ) , 68 1. uruddb ersdss h planets the disks, debris by surrounded } INTRODUCTION A − U(aose l 08.Teere- These 2008). al. et (Marois AU 2,3 T E 0 a nrwW Howard W. Andrew , tl mltajv 11/10/09 v. emulateapj style X . EE OINEOLNT RMKC OBSERVATORY KECK FROM EXOPLANETS JOVIAN SEVEN 21 ≈ H 33 D909 D114,H 060 D100,H 136418 HD 180902, HD 206610, HD 181342, HD 95089, HD 4313, (HD ehius ailvlcte—lntr ytm:formation—sta systems: velocities—planetary radial techniques: ≤ 2 U riigjs inside just orbiting AU, 120 ao .Wright T. Jason [Fe/H] EIE TR N HI OPNOSIV. COMPANIONS THEIR AND STARS A RETIRED . M 3 ≤ Jup +0 n h com- the and , β . i announced Pic > a − 6 h lnt r l oemsieta uie ( Jupiter than massive more all are planets The 26. rf eso etme 6 2018 26, September version Draft 6 4 2 AU). 120 er .Fischer A. Debra , rna .Bowler P. Brendan , U epeetmliantd htmtyfo h T3 the from photometry millimagnitude present We AU. 1 maged ornia larly, ABSTRACT ol- en 8 . . 1 ≤ htteocrec fJva lnt clswt stel- with ( scales stars planets A-type Jovian mass: of counter- lar found occurrence “retired” have giants) the the and fre- that (subgiants around dwarfs al. the A-type et planets of of Liu parts giant al. Measurements 2007; et of al. Reffert et 2009). quency surveys Niedzielski 2005; al. Döllinger 2007; imaging et al. 2008; al. may direct et et Setiawan dwarfs for Sato 2003; A stars 2006; target that al. et ideal apparent (Hatzes be recent becoming fact of mas- is in of light it searches in stars planet However, sive fainter, Doppler-based with Solar from stars. discoveries systems the central ra- to in massive contrast compared make population less unfavorable star-planet stars stellar are the the A tios because of that and 3% given neighborhood than unlikely, less seem up first at might etdi h ikSbinsSre,wihcom- which Survey, ( Subgiants stars al. de- et Lick massive planets Bowler of 31 the from analysis prises dwarfs. in distinct statistical FGK a from is tected around drawn performed that planets are (2010) population of stars parent A those statistical around planets a 2007b; of al. Sun- et acteristics around (Johnson dwarfs found (FGK) 2008). planets al. K farther et do and Sato orbit G than and F, stars like, 2007) their Mayor & are from plan- (Lovis stars imaged A massive of retired al. sample more around et current planets Johnson the Doppler-detected 2010; like ets, al. just planet et And giant Bowler a 2009). 2007a; harbor al. to et dwarfs M (Johnson than likely more times h rqec fpaesrsn oadlwrmasses lower distribu- toward with typically mass-period rising is relationship, planets The dwarfs of double-power-law FGK frequency a . the around by years exoplanets described 5 of past tion the for htbt ytm eedsoee riigAstars A orbiting discovered were systems both That ned hr ssrn vdneta h ria char- orbital the that evidence strong is there Indeed, M ⋆ 7 /M oadIsaacson Howard , 3 rgr .Henry W. Gregory , ⊙ ≤ r fseta yeF n ,and K, and G F, type spectral of ars ino h bevdrda velocity radial observed the of tion vrdaon omrAtp stars A-type former around overed gn surveys. aging 1 niaieo diinldistant additional of indicative s . ,rdi3 radii 9, nto fselrms.Three mass. stellar of unction ascmain nKeplerian in companions mass dicesdocrec rate, occurrence increased nd ekOsraoy l seven All Observatory. Keck trn hw hs tr to stars these shows itoring . 4 M 3 ≤ M ⋆ ⋆ R & 5 1 ⋆ efryW Marcy W. Geoffrey , & /R 1 s individual rs: . D212771) HD , M 5 ⊙ 1 M . ≤ M 5 P ⊙ 6 r tlat5 least at are ) sin . ,and 1, ⊙ > i monitored ) 4 , 2 and remaining flat in logarithmic semimajor-axis bins other planet search programs and are known to exhibit from ∼ 0.05 AU to ∼ 5 AU (Tabachnik & Tremaine velocity jitter > 10ms−1 (Sato et al. 2005; Hekker et al. 2002; Lineweaver & Grether 2003; Cumming et al. 2008; 2006; Niedzielski et al. 2009). The lower MV restriction Johnson 2009). Based on the 7 planet detections from avoids Cepheid variables, and the upper limit excludes the Lick survey, Bowler et al. concluded that the power- stars with masses less than 1.3 M⊙ when compared to law indices of the distribution of planets around A stars the Solar-metallicity ([Fe/H] = 0) stellar model tracks and Sun-like stars differ at the 4-σ level; the planets in of Girardi et al. (2002). We also excluded stars in the their sample all have MP sin i > 1.5 MJup and none orbit clump region (B − V > 0.8, MV < 2.0) to avoid the within 1 AU. However, their small sample size precluded closely-spaced, and often overlapping mass tracks in that a determination of the exact shape of the mass-period region of the theoretical H–R diagram. +9 distribution. Fortunately, given the 26−8% occurrence rate measured from the Lick survey, it will not take long 2.2. Stellar Properties to build a statistical ensemble comparable to the collec- Atmospheric parameters of the target stars are esti- tion of planets around less massive stars. mated from iodine-free, “template” spectra using the To increase the collection of planets detected around LTE spectroscopic analysis package Spectroscopy Made massive stars, and to study the relationships among Easy (SME; Valenti & Piskunov 1996), as described by the characteristics of stars and the properties of their Valenti & Fischer (2005) and Fischer & Valenti (2005). planets, we are conducting a survey of massive sub- To constrain the low surface gravities of the evolved stars giants at Keck and Lick Observatories. The de- we used the iterative scheme of Valenti et al. (2009), creased rotation rates and cooler surface temperatures which ties the SME-derived value of log g to the gravity of these evolved stars make them much more ideal inferred from the Yonsei-Yale (Y2; Yi et al. 2004) stellar Doppler-survey targets compared to their massive main- model grids. The analysis yields a best-fit estimate of sequence progenitors (Galland et al. 2005). The ob- Teff , log g, [Fe/H], and Vrot sin i. The properties of the served effects of stellar mass on the properties of plan- majority of our targets from Lick and Keck are listed in ets have important implications for planet formation the fourth edition of the Spectroscopic Properties of Cool modeling (Ida & Lin 2005; Kennedy & Kenyon 2008; Stars Catalog (SPOCS IV.; Johnson et al. 2010, in prep). Kretke et al. 2009; Currie 2009; Dodson-Robinson et al. We adopt the SME parameter uncertainties described in 2009); the interpretation of observed structural fea- the error analysis of Valenti & Fischer (2005). tures in the disks around massive stars (Wyatt et al. The luminosity of each star is estimated from the 1999; Quillen 2006; Brittain et al. 2009); and the plan- apparent V-band magnitude, the bolometric correc- ning of current and future planet search efforts, such tion (Flower 1996), and the parallax from Hipparcos as the Gemini Planet Imager (GPI; Macintosh et al. (van Leeuwen 2007). From Teff and luminosity, we de- 2008), Spectro-Polarimetric High-contrast Exoplanets termine the stellar mass, radius, and an age estimate by REsearch (SPHERE; Claudi et al. 2006), the Near associating those observed properties with a model from Infrared Coronographic Imager (NICI; Artigau et al. the Y2 stellar interior calculations (Yi et al. 2004). We 2008), and Project 1640 (Hinkley et al. 2008). Our Lick also measure the chromospheric emission in the Ca II line survey has resulted in the discovery of 7 new Jovian cores (Wright et al. 2004; Isaacson 2009), providing an planets orbiting evolved stars more massive than the SHK value on the Mt. Wilson system, which we convert ′ Sun (Johnson et al. 2006, 2007b, 2008; Peek et al. 2009; to log RHK as per Noyes et al. (1984). Bowler et al. 2010). In this contribution, we present the The stellar properties of the seven stars presented first seven planets discovered in the expanded Keck sur- herein are summarized in Table 1. vey. 3. OBSERVATIONS AND ANALYSIS 2. A DOPPLER SURVEY OF SUBGIANTS AT 3.1. Keck Spectra and Doppler Analysis KECK OBSERVATORY We obtained spectroscopic observations at Keck Obser- 2.1. Target Selection vatory using the HIRES spectrometer with a resolution ′′ We are monitoring the radial velocities (RV) of a sam- of R ≈ 55, 000 with the B5 decker (0. 86 width) and red ple of 500 evolved stars at Keck Observatory. The Keck cross-disperser (Vogt et al. 1994). We use the HIRES ex- program expands upon our Doppler survey of 120 sub- posure meter to ensure that all observations receive uni- giants at Lick Observatory, which has been ongoing since form flux levels independent of atmospheric transparency 2004(Johnson et al. 2006; Peek et al. 2009). The stars in variations, and to provide the photon-weighted exposure the Lick program have now been folded into the Keck tar- midpoint which is used for the barycentric correction. get list and that subset of brighter subgiants (V < 7.25) Under nominal atmospheric conditions, a V = 8 target is currently monitored at both observatories. We began requires an exposure time of 90 seconds and results in a the Keck survey in 2007 April for the majority of our signal-to-noise ratio of 190 at 5500 A.˚ target stars, and a handful of stars were part of the orig- The spectroscopic observations are made through a inal Keck planet search sample dating as far back as 1997 temperature-controlled Pyrex cell containing gaseous io- (Marcy et al. 2008). dine, which is placed at the entrance slit of the spectrom- We selected the targets for the expanded Keck survey eter. The dense set of narrow molecular lines imprinted from the Hipparcos catalog based on the criteria 1.8 < on each stellar spectrum from 5000 A˚ to 6000 A˚ provides MV < 3.0, 0.8 < B − V < 1.1, and V . 8.5 (ESA 1997; a robust, simultaneous wavelength calibration for each van Leeuwen 2007). We chose the red cutoff to avoid red observation, as well as information about the shape of the giants, the majority of which are already monitored by spectrometer’s instrumental response (Marcy & Butler 3

1992). Doppler shifts are measured from each spectrum Therefore, all five of the planetary candidate stars in using the modeling procedure described by Butler et al. Table 2 are photometrically constant to the approximate (1996). The instrumental uncertainty of each measure- limit of the APT observations. The measured photomet- ment is estimated based on the weighted standard devi- ric stability supports the planetary interpretation of the ation of the mean Doppler-shift measured from each of radial velocity variations. The two stars that we did not ≈ 700 2–A˚ spectral chunks. In a few instances we made observe photometrically, HD 136418 and and HD 181342, two or more successive observations of the same star and have similar masses, colors, and activity levels (Table 2) binned the velocities (in 2 hr time intervals), thereby re- as the five stars we did observe and so are likely to be ducing the associated measurement uncertainty. photometrically constant as well. 3.2. Photometric Measurements 3.3. Orbit Analysis We also acquired brightness measurements of five of For each star we performed a thorough search of the the seven planetary candidate host stars with the T3 measured velocities for the best-fitting, single-planet Ke- 0.4 m automatic photometric telescope (APT) at Fair- plerian orbital model using the partially-linearized, least- born Observatory. T3 observed each program star dif- squares fitting procedure described in Wright & Howard ferentially with respect to two comparisons stars in (2009) and implemented in the IDL package RVLIN9. Be- the following sequence, termed a group observation: fore searching for a best-fitting solution, we increased K,S,C,V,C,V,C,V,C,S,K, where K is a check (or sec- the measurement uncertainties by including an error con- ondary comparison) star, C is the primary comparison tribution due to stellar ”jitter.” The jitter accounts for star, V is the program (normally a variable) star, and any unmodeled noise sources intrinsic to the star such S is a sky reading. Three V − C and two K − C dif- as rotational modulation of surface inhomogeneities and ferential magnitudes are computed from each sequence pulsation (Saar et al. 1998; Wright 2005; Makarov et al. and averaged to create group means. Group mean dif- 2009; Lagrange et al. 2010). ferential magnitudes with internal standard deviations greater than 0.01 mag were rejected to eliminate the observations taken under non-photometric conditions. The 100 RVs for 72 "stable" stars surviving group means were corrected for differential ex- σ −1 tinction with nightly extinction coefficients, transformed = 5.1 m s to the Johnson system with yearly-mean transformation 80 coefficients, and treated as single observations thereafter. The typical precision of a single group-mean observa- 60 tion from T3, as measured for pairs of constant stars, is ∼0.004–0.005 mag (e.g., Henry et al. 2000, tables 2 & 40 3). Further information on the operation of the T3 APT can be found in Henry et al. (1995b,a) and Eaton et al. 20

(2003). Number of Measurements Our photometric observations are useful for eliminat- 0 −20 −10 0 10 20 ing potential false positives from the sample of new plan- Radial Velocity [m s−1] ets. Queloz et al. (2001) and Paulson et al. (2004) have demonstrated how rotational modulation in the visibil- ity of starspots on active stars can result in periodic ra- 100 −1 dial velocity variations and potentially lead to erroneous Median = 1.2 m s planetary detections. Photometric results for the stars 80 in the present sample are given in Table 2. Columns 7–10 give the standard deviations of the V − C and 60 K −C differential magnitudes in the B and V passbands with the 3σ outliers removed. With the exception of 40 HD 206610, all of the standard deviations are small and approximately equal to the measurement precision of the 20 Number of Measurements telescope. 0 For HD 206610, the standard deviations of the four 0.0 0.5 1.0 1.5 2.0 2.5 data sets (V − C)B, (V − C)V , (K − C)B , and (K − C)V Internal Measurement Error [m s−1] are all larger than 0.01 mag and indicate photometric variability. Periodogram analyses revealed that all four Fig. 1.— Top—Distribution of RVs for 72 standard stars, com- data sets have a photometric period of 0.09 day and an prising a total of 382 measurements. The dashed line shows the amplitude of ∼ 0.03 mag. Thus, the variability must best-fitting Gaussian with a width σ = 5.1ms−1. Bottom – Distribution of internal measurement uncertainties for 382 RV mea- arise from HD 206610’s primary comparsion star (C = 1 surements. The median is 1.2 m s− . Together with the distribu- HD 205318), which is included in all four data sets. Given tion of RVs in the top panel, this provides us with a jitter estimate its period, amplitude, and early-F spectral class, it is of5ms−1, which we apply to all of the stars presented herein. probably a new δ Scuti star. We computed new differential magnitudes for HD 206610 using the check star (K) We estimate the jitter for our subgiants based on the to form the variable minus check data sets (V − K)B velocity variability of a sample of ”stable” stars, for and (V − K)V . The standard deviations of these two 9 data sets are 0.0066 and 0.0067 mag, respectively. http://exoplanets.org/code/ 4 which we have obtained > 4 observations over a time for a particular model with k free parameters and N span greater than 2 years. These stars do not show ev- data points10. A difference of & 2 between BIC values idence of an orbital companion, except in a few cases with and without a trend indicates that there is sufficient where the stars exhibit a linear trend. In those cases evidence for a more complex model (Kuha 2004). we remove the trend using a linear fit and consider the We also use the MCMC-derived pdf for the velocity scatter in the residuals. Figure 1 shows the distribution trend parameter to estimate the probability that a trend of RVs for all 72 stable stars, comprising 382 measure- is actually present in the data. If the 99.7 percentile ments. We fit a Gaussian function to the distribution of the pdf lies above or below 0 m s−1 yr−1 then we with a width σ = 5.1ms−1. The measurement uncer- adopt the model with the trend. The BIC and MCMC tainties, shown in the lower panel, span 0.6–2.5 m s−1, methods yield consistent results for the planet candidates with a median value of 1.2 m s−1. We subtracted this described in § 4. median internal error in quadrature from the measured width of the distribution of RVs to produce a jitter es- 3.5. False-Alarm Evaluation timate of 4.95 m s−1. In the analysis of each star’s RV For each planet candidate we consider the null– time series we round this value up and adopt a uniform hypothesis that the apparent periodicity arose by chance jitter estimate of 5 m s−1, which we add in quadrature to from larger-than-expected radial velocity fluctuations the measurement uncertainties before searching for the and sparse sampling. We test this possibility by cal- best–fitting orbit. culating the false-alarm probability (FAP) based on After identifying the best–fitting model, we use a 2 Markov-Chain Monte Carlo (MCMC) algorithm to es- the goodness-of-fit statistic ∆χν (Howard et al. 2009; Marcy et al. 2005; Cumming 2004), which is the differ- timate the parameter uncertainties (See, e.g. Ford 2005; 2 Winn et al. 2007). MCMC is a Bayesian inference tech- ence between two values of χν : one from the single-planet nique that uses the data to explore the shape of the like- Keplerian fit and one from the fit of a linear trend to the lihood function for each parameter of an input model. data. Each trial is constructed by keeping the times of observation fixed and scrambling the measurements, with At each step, one parameter is selected at random and 2 altered by drawing a random variate from a normal dis- replacement. We record the ∆χν value after each trial tribution. If the resulting χ2 value for the new trial orbit and repeat this process for 10,000 trial data sets. For 2 the ensemble set we compare the resulting distribution is less than the previous χ value, then the trial orbital 2 parameters are added to the chain. If not, then the prob- of ∆χν to the value from the fit to the original data. ability of adopting the new value is set by the ratio of the The planets presented below all have FAP < 0.001, cor- probabilities from the previous and current trial steps. If responding to < 0.5 false alarms for our sample of 500 the current trial is rejected then the parameters from the stars. previous step are adopted. We alter the standard deviations of the random pa- 4. RESULTS rameter variates so that the acceptance rates are be- We have detected seven new Jovian planets orbiting tween 20% and 40%. The initial parameters are chosen evolved, subgiant stars. The RV time series of each host- from the best-fitting orbital solutions derived using the star is plotted in Figures 2–8, where the error bars show least-squares method described above, and each chain is the quadrature sum of the internal errors and the jit- run for 107 steps. The initial 10% of the chains are ex- ter estimate of 5 m s−1, as described in § 3.3. The RV cluded from the final estimation of parameter uncertain- measurements for each star are listed in Tables 3–9, to- ties to ensure uniform convergence. We verify that con- gether with the Julian Date of observation and the in- vergence is reached by running five shorter chains with ternal measurement uncertainties (without jitter). The 106 steps and checking that the Gelman-Rubin statistic best–fitting orbital parameters and physical character- (Gelman & Rubin 1992) for each parameter is near unity istics of the planets are summarized in Table 10, along (. 1.02) and that a visual inspection of the history plots with their uncertainties. When appropriate we list notes suggests stability. for some of the individual planetary systems. The resulting “chains” of parameters form the poste- HD 95089, HD 136418, HD 180902—The orbit models rior probability distribution, from which we select the for these three stars include linear trends. We interpret 15.9 and 84.1 percentile levels in the cumulative distri- the linear trend as a second orbital companion with a butions as the “one-sigma” confidence limits. In most period longer than the time baseline of the observations. cases the posterior probability distributions were approx- HD 181342—The time sampling of HD 181342 is imately Gaussian. sparser than most of the the other stars presented in this work. However, the large amplitude of the variations and 3.4. Testing RV Trends observations clustered near the quadrature points result 2 We use the Bayesian Information Criterion (BIC; in a well-defined χν minimum in the orbital parameter Schwarz 1978; Liddle 2004) and the MCMC posterior space. The FAP for the orbit solution is 0.0064%. probability density functions (pdf) to determine whether HD 212771—This low-mass subgiant has a mass M⋆ = there is evidence for a linear velocity trend (Bowler et al. 1.15 M⊙, indicating that it had a spectral type of early- 2010). The BIC rewards better-fitting models but penal- G to late-F while on the main sequence. In addition izes overly complex models, and is given by to being one of our least massive targets, HD212771 is

10 L 2 BIC ≡−2 ln Lmax + k ln N, (1) The relationship between max and χmin is only valid under the assumption that the errors are described by a Gaussian, which 2 is approximately valid for our analyses. where Lmax ∝ exp(−χmin/2) is the maximum likelihood 5

100 P = 356.0 d HD 4313 P = 663.0 d HD 181342 100 K = 46.9 m s−1 Keck Obs. K = 52.3 m s−1 Keck Obs.

] e = 0.041 ] e = 0.18 −1 −1 50 50

0 0 Radial Velocity [m s Radial Velocity [m s −50 M sini = 2.3 M M sini = 3.3 M P Jup −50 P Jup 2007 2008 2009 2010 2007 2008 2009 2010 Year Year

Fig. 2.— Relative RVs of HD 4313 measured at Keck Obser- Fig. 4.— Relative RVs of HD 181342 measured at Keck Obser- vatory. The error bars are the quadrature sum of the internal vatory. The error bars are the quadrature sum of the internal measurement uncertainties and 5 m s−1 of jitter. The dashed line measurement uncertainties and 5 m s−1 of jitter. The dashed line shows the best-ﬁtting orbit solution of a single Keplerian orbit. shows the best-ﬁtting orbit solution of a single Keplerian orbit. The solution results in residuals with an rms scatter of 3.7 m s−1 The solution results in residuals with an rms scatter of 4.7 m s−1 2 2 and pχν = 0.79. and pχν = 1.14.

P = 507.1 d −1 K = 23.5 m s P = 610.4 d HD 206610 40 e = 0.16 i −1 MPsin = 1.2 MJup K = 40.7 m s Keck Obs.

0 ] e = 0.23 ] −1 50

−1 −40 HD 95089 Keck Obs.

2007 2008 2009 2010 Year 40 0 20 Radial Velocity [m s Radial Velocity [m s 0

−50 M sini = 2.2 M −20 P Jup Linear Trend Removed 2007 2008 2009 2010 2007 2008 2009 2010 Year Year Fig. 3.— Relative RVs of HD 95089 measured at Keck Obser- Fig. 5.— Relative RVs of HD 206610 measured at Keck Obser- vatory. The error bars are the quadrature sum of the internal vatory. The error bars are the quadrature sum of the internal measurement uncertainties and 5 m s−1 of jitter. The dashed line measurement uncertainties and 5 m s−1 of jitter. The dashed line shows the best-fitting orbit solution of a single Keplerian orbit plus shows the best-fitting orbit solution of a single Keplerian orbit. a linear trend (dv/dt = 30.9±1.9ms−1 yr−1). The solution results The solution results in residuals with an rms scatter of 4.8 m s−1 −1 2 2 in residuals with an rms scatter of 5.7 m s and pχν = 1.32. he and pχν = 1.06. lower panel shows the RVs with the linear trend removed. different from those of planets around FGK stars. Their also one of the most metal-poor stars in the Keck sample findings suggest that the formation and migration mech- [Fe/H] = −0.21. anisms of planets changes dramatically with increas- 5. ing stellar mass. The planets reported in this work SUMMARY AND DISCUSSION strengthen that conclusion. The five new planets we We report the detection of seven new Jovian planets have discovered around stars with M⋆ > 1.5 M⊙ all or- orbiting evolved stars. These detections come from the bit beyond 1 AU and have minimum masses MP sin i > sample of subgiants that we are monitoring at Lick and 1 MJup. These properties contrast with those of plan- Keck Observatories. The host-stars have masses in the ets orbiting less massive stars, which have a nearly flat range 1.15 M⊙ to 1.9 M⊙, radii 3.4 ≤ R⋆/R⊙ ≤ 6.1, and distribution in log a from a = 0.05 AU to a = 1 AU metallicities −0.21 ≤ [Fe/H] ≤ +0.26. Five of the host- (Cumming et al. 2008), and a steeply rising mass func- stars have masses M⋆ > 1.5 M⊙, and are therefore the tion with d ln N/d ln MP = −1.4. Successful theories of evolved counterparts of the A-type stars. We also de- the origin and orbital evolution of giant planets will need rived a jitter estimate for our sample of evolved stars to account for the discontinuity between the distribu- and find that subgiants are typically stable to within tions of orbital parameters for planets around Sun-like 5ms−1. The observed jitter of subgiants makes them and A-type stars (Kennedy & Kenyon 2008; Currie 2009; uniquely stable Doppler targets among massive, evolved Kretke et al. 2009). stars (Fischer et al. 2003; Hekker et al. 2006). The abundance of super-Jupiters (MP sin i > 1 MJup) Bowler et al. (2010) found that the minimum masses detected around massive stars bodes well for future and semimajor axes of planets around A stars are very direct-imaging surveys. In addition to harboring the 6

markers of massive objects in wide orbits around nearby 200 P = 479.2 d HD 180902 K = 30.7 m s−1 Keck Obs. stars, and therefore warrant additional scrutiny from RV e = 0.093 100 i MPsin = 1.6 MJup monitoring and high-contrast imaging. 0 ] −1 −100 We thank the many observers who contributed to the −200 observations reported here. We gratefully acknowledge

2007 2008 2009 2010 Year the eﬀorts and dedication of the Keck Observatory staﬀ, 40 especially Grant Hill, Scott Dahm and Hien Tran for 20 their support of HIRES and Greg Wirth for support

Radial Velocity [m s 0 100 −20 P = 373.3 d HD 212771 K = 58.2 m s−1 Keck Obs. −40 Linear Trend Removed e = 0.11 ]

2007 2008 2009 2010 −1 50 Year Fig. 6.— Relative RVs of HD 180902 measured at Keck Obser- vatory. The error bars are the quadrature sum of the internal 0 measurement uncertainties and 5 m s−1 of jitter. The dashed line shows the best-ﬁtting orbit solution of a single Keplerian orbit plus −1 −1 a linear trend (dv/dt = 135.4 ± 3.5ms yr ). The solution re- −50 −1 2 Radial Velocity [m s sults in residuals with an rms scatter of 3.3 m s and pχν = 0.98. The lower panel shows the RVs with the linear trend removed. i MPsin = 2.3 MJup −100 2007 2008 2009 2010 Year P = 464.3 d HD 136418 100 K = 44.7 m s−1 Keck Obs. Fig. 8.— Relative radial velocity measurements of HD 212771.

] e = 0.26 The error bars are the quadrature sum of the internal measure- −1 ment uncertainties and 5 m s−1 of jitter. The dashed line shows the best-ﬁtting orbit solution of a single Keplerian orbit. The so- 50 lution results in residuals with an rms scatter of 5.8 m s−1 and 2 pχν = 1.29. HD 212771 has a mass M⋆ = 1.15 M⊙, indicating that it was either an early-G or late-F star when it was on the main sequence. 0 Radial Velocity [m s

i MPsin = 2.0 MJup of remote observing. We are also grateful to the time −50 assignment committees of NASA, NOAO, Caltech, and 2007 2008 2009 2010 the University of California for their generous alloca- Year tions of observing time. A. W. H. gratefully acknowl- Fig. 7.— Relative RVs of HD 136418 measured at Keck Obser- edges support from a Townes Post-doctoral Fellowship vatory. The error bars are the quadrature sum of the internal at the U.C. Berkeley Space Sciences Laboratory. J.A.J. measurement uncertainties and 5 m s−1 of jitter. The dashed line thanks the NSF Astronomy and Astrophysics Postdoc- shows the best-ﬁtting orbit solution of a single Keplerian orbit plus 1 1 toral Fellowship program for support in the years leading a linear trend (dv/dt = −5.3 ± 1.7ms− yr− ). The solution re- −1 2 to the completion of this work, and acknowledges support sults in residuals with an rms scatter of 5.0 m s and pχν = 1.15. HD 136418 has a mass M⋆ = 1.33 M⊙, making it a former F-type form NSF grant AST-0702821 and the NASA Exoplan- star. ets Science Institute (NExScI). G. W. M. acknowledges NASA grant NNX06AH52G. J. T. W. received support massive planets that are predicted to be the most easily from NSF grant AST-0504874. G.W.H acknowledges detectable in high-contrast images, A-type dwarfs have support from NASA, NSF, Tennessee State University, the added beneﬁt of being naturally young. A 2 M⊙ and the State of Tennessee through its Centers of Ex- star has a main-sequence lifetime of only ∼ 1 Gyr, which cellence program. Finally, the authors wish to extend means that Jovian planets in wide orbits will be young special thanks to those of Hawaiian ancestry on whose and thermally bright. Three of the planets in Table 10 sacred mountain of Mauna Kea we are privileged to be show linear velocity trends indicative of additional long- guests. Without their generous hospitality, the Keck ob- period companions. These linear trends provide clear servations presented herein would not have been possible.

REFERENCES Artigau, E.,´ et al. 2008, Society of Photo-Optical Instrumentation Dodson-Robinson, S. E., et al. 2009, ApJ, 707, 79 Engineers (SPIE) Conference Series, Vol. 7014, NICI: D¨ollinger, M. P., et al. 2009, A&A, 505, 1311 combining coronagraphy, ADI, and SDI (SPIE) Eaton, J. A., Henry, G. W., & Fekel, F. C. 2003, The Future of Bowler, B. P., et al. 2010, ApJ, 709, 396 Small Telescopes In The New Millennium. Volume II - The Brittain, S. D., Najita, J. R., & Carr, J. S. 2009, ApJ, 702, 85 Telescopes We Use, 189 Butler, R. P., et al. 1996, PASP, 108, 500 ESA, . 1997, VizieR Online Data Catalog, 1239, 0 Claudi, R. U., et al. 2006, SPIE, 6269 Fischer, D. A., et al. 2003, ApJ, 586, 1394 Cumming, A. 2004, MNRAS, 354, 1165 Fischer, D. A. & Valenti, J. 2005, ApJ, 622, 1102 Cumming, A., et al. 2008, PASP, 120, 531 Fitzgerald, M. P., Kalas, P. G., & Graham, J. R. 2009, ApJ, 706, Currie, T. 2009, ApJ, 694, L171 L41 7

Flower, P. J. 1996, ApJ, 469, 355 Makarov, V. V., et al. 2009, ApJ, 707, L73 Ford, E. B. 2005, AJ, 129, 1706 Marcy, G., et al. 2005, Progress of Theoretical Physics Galland, F., et al. 2005, A&A, 443, 337 Supplement, 158, 24 Gelman, A. & Rubin, D. B. 1992, Statistical Science, 7, 457 Marcy, G. W. & Butler, R. P. 1992, PASP, 104, 270 Girardi, L., et al. 2002, A&A, 391, 195 Marcy, G. W., et al. 2008, Physica Scripta Volume T, 130, 014001 Hatzes, A. P., et al. 2003, ApJ, 599, 1383 Marois, C., et al. 2008, Science, 322, 1348 Hekker, S., et al. 2006, A&A, 454, 943 Niedzielski, A., et al. 2009, ApJ, 693, 276 Henry, G. W., et al. 1995a, ApJS, 97, 513 Niedzielski, A., et al. 2007, ApJ, 669, 1354 Henry, G. W., Fekel, F. C., & Hall, D. S. 1995b, AJ, 110, 2926 Noyes, R. W., et al. 1984, ApJ, 279, 763 Henry, G. W., et al. 2000, ApJS, 130, 201 Paulson, D. B., et al. 2004, AJ, 127, 1644 Hinkley, S., et al. 2008, SPIE, 7015 Peek, K. M. G., et al. 2009, PASP, 121, 613 Howard, A. W., et al. 2009, ApJ, 696, 75 Queloz, D., et al. 2001, A&A, 379, 279 Ida, S. & Lin, D. N. C. 2005, Progress of Theoretical Physics Quillen, A. C. 2006, MNRAS, 372, L14 Supplement, 158, 68 Reﬀert, S., et al. 2006, ApJ, 652, 661 Isaacson, H. T. 2009, 41, 206 Saar, S. H., Butler, R. P., & Marcy, G. W. 1998, ApJ, 498, L153+ Johnson, J. A. 2009, PASP, 121, 309 Sato, B., et al. 2005, ApJ, 633, 465 Johnson, J. A., et al. 2007a, ApJ, 670, 833 Sato, B., et al. 2007, ApJ, 661, 527 Johnson, J. A., et al. 2007b, ApJ, 665, 785 Sato, B., et al. 2008, PASJ, 60, 1317 Johnson, J. A., et al. 2009, ArXiv e-prints Schwarz, G. 1978, The Annals of Statistics, 461 Johnson, J. A., et al. 2006, ApJ, 652, 1724 Setiawan, J., et al. 2005, A&A, 437, L31 Johnson, J. A., et al. 2008, ApJ, 675, 784 Tabachnik, S. & Tremaine, S. 2002, MNRAS, 335, 151 Kalas, P., et al. 2008, Science, 322, 1345 Valenti, J. A., et al. 2009, ApJ, 702, 989 Kennedy, G. M. & Kenyon, S. J. 2008, ApJ, 673, 502 Valenti, J. A. & Fischer, D. A. 2005, ApJS, 159, 141 Kretke, K. A., et al. 2009, ApJ, 690, 407 Valenti, J. A. & Piskunov, N. 1996, A&AS, 118, 595 Kuha, J. 2004, Sociological Methods Research, 33, 188 van Leeuwen, F. 2007, A&A, 474, 653 Lafreni`ere, D., Jayawardhana, R., & van Kerkwijk, M. H. 2008, Vogt, S. S., et al. 1994, in Proc. SPIE Instrumentation in ApJ, 689, L153 Astronomy VIII, David L. Crawford; Eric R. Craine; Eds., Lagrange, A., Desort, M., & Meunier, N. 2010, arXiv:1001.1449 Volume 2198, p. 362, ed. D. L. Crawford & E. R. Craine, 362–+ Lagrange, A., et al. 2009a, A&A, 506, 927 Winn, J. N., Holman, M. J., & Fuentes, C. I. 2007, AJ, 133, 11 Lagrange, A.-M., et al. 2009b, A&A, 493, L21 Wright, J. T. 2005, PASP, 117, 657 Liddle, A. R. 2004, MNRAS, 351, L49 Wright, J. T. & Howard, A. W. 2009, ApJS, 182, 205 Lineweaver, C. H. & Grether, D. 2003, ApJ, 598, 1350 Wright, J. T., et al. 2004, ApJS, 152, 261 Liu, Y.-J., et al. 2008, ApJ, 672, 553 Wyatt, M. C., et al. 1999, ApJ, 527, 918 Lovis, C. & Mayor, M. 2007, A&A, 472, 657 Yi, S. K., Demarque, P., & Kim, Y.-C. 2004, Ap&SS, 291, 261 Macintosh, B. A., et al. 2008, SPIE, 7015 8

TABLE 1 Stellar Parameters

Parameter HD 4313 HD 95089 HD 181342 HD 206610 HD 180902 HD 136418 HD 212771

V 7.83 7.92 7.55 8.34 7.78 7.88 7.60 B − V 0.96 0.94 1.02 1.01 0.94 0.93 0.88 Distance (pc) 137 (14) 139 (16) 110.6 (7.5) 194 (36) 110 (10) 98.2 (5.6) 131 (14) MV 2.2 (0.3) 2.1 (0.3) 2.2 (0.2) 2.2 (0.4) 2.5 (0.3) 2.7 (0.2) 2.2 (0.3) [Fe/H] +0.14 (0.03) +0.05 (0.03) +0.26 (0.03) +0.14 (0.03) 0.04 (0.03) -0.07 (0.03) -0.21 (0.03) Teﬀ (K) 5035 (44) 5002 (44) 5014 (44) 4874 (44) 5030 (44) 5071 (44) 5121 (44) −1 Vrot sin i (km s ) 2.76 (0.5) 2.74 (0.5) 3.04 (0.5) 2.57 (0.5) 2.88 (0.5) 0.17 (0.5) 2.63 (0.5) log g 3.4 (0.06) 3.4 (0.06) 3.4 (0.06) 3.3 (0.06) 3.5 (0.06) 3.6 (0.06) 3.5 (0.06) M∗ (M⊙) 1.72 (0.12) 1.58 (0.11) 1.84 (0.13) 1.56 (0.11) 1.52 (0.11) 1.33 (0.09) 1.15 (0.08) R∗ (R⊙) 4.9 (0.1) 4.9 (0.1) 4.6 (0.1) 6.1 (0.1) 4.1 (0.1) 3.4 (0.1) 5.0 (0.1) L∗ (R⊙) 14.1 (0.5) 13.5 (0.5) 12.0 (0.5) 18.9 (0.6) 9.4 (0.5) 6.8 (0.5) 15.4 (0.5) Age (Gyr) 2.0 (0.5) 2.5 (0.9) 1.8 (0.4) 3 (1) 2.8 (0.7) 4 (1) 6 (2) SHK 0.12 0.13 0.12 0.14 0.15 0.14 0.16 ′ log RHK -5.27 -5.22 -5.31 -5.23 -5.14 -5.19 -5.09

TABLE 2 Summary of Photometric Observations From Fairborn Observatory

− − − − Program Comparison Check Date Range Duration σ(V C)B σ(V C)V σ(K C)B σ(K C)V − Star Star Star (HJD 2,440,000) (days) Nobs (mag) (mag) (mag) (mag) Variability (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11)

HD 4313 HD 4627 HD 4526 54756–55222 466 188 0.0039 0.0046 0.0038 0.0056 Constant HD 95089 HD 94401 HD 93102 55139–55237 98 58 0.0056 0.0059 0.0045 0.0064 Constant HD 180902 HD 179949 HD 181240 55122–55126 4 3 0.0032 0.0031 0.0010 0.0056 Constant? HD 206610 HD 205318 HD 208703 54756–55170 414 88 0.0183a 0.0140a 0.0172 0.0124 Constant HD 212771 HD 212270 HD 213198 55119–55170 51 60 0.0043 0.0048 0.0051 0.0065 Constant

a Comparison star HD 205318 is variable in brightness, so we recomputed the standard deviations of the program star from the (V − K)B and (V − K)V diﬀerential magnitudes and ﬁnd them to be 0.0066 and 0.0067 mag in B and V, respectively.

TABLE 3 Radial Velocities for HD 4313