Time Allocation Committee for Application No. MPG time at the ESO 2.2m-telescope c/o MPI f¨urAstronomie Observing period Fall 2014 K¨onigstuhl17 Received D-69117 Heidelberg / Germany

APPLICATION FOR OBSERVING TIME

from X MPIA MPG institute other

1. Telescope: 2.2-m X 093.A-9004(A) P

2.1 Applicant Simona Ciceri Max-Planck-Institute for Astronomy Name Institute K¨onigstuhl17 69117 Heidelberg street ZIP code - city Germany [email protected] ESO User Portal username e-mail

2.2 Collaborators T. Henning1, L. Mancini1 1MPIA name(s) institute(s) G. Bakos2, J. Hartman2 2Princeton University name(s) institute(s)

2.3 Observers S. Ciceri L. Mancini name name By specifying the names under item 2.3 it is obligatory to also send out these observers to La Silla, if required. Correspondence on the rating of this application will be sent to the applicant (P.I.) as quoted under 2.1 above.

3. Observing programme: Category: E

Title : Radial velocity confirmation of HAT-South exoplanet candidates Abstract : Nowadays transit surveys are among the most successful techniques to detect extrasolar planets. The HAT-South transit network is now producing a regular stream of transiting planet candidates. We propose to support this program by performing spectroscopic follow- up observations with FEROS for 17 high-priority planet candidates. Among these candidates there are several with orbital periods longer than 10 days, and with radii in the Neptune- regime; all of these candidates orbit around relatively bright stars, so that the planetary masses can be directly measured through RVs. The observations that we propose to carry out will aid in rejecting false positives, confirming true planets, and determining their properties, including masses, radii, and orbital eccentricities.

4. Instrument: WFI X FEROS GROND

5. Brightness range of objects to be observed: from 8.2 to 13.5 V-mag

6. Number of hours: applied for already awarded still needed 83 529 250 no restriction grey dark

7. Optimum date range for the observations: ...... 1.10.2014 – 31.03.2015 Usable range in local sideral time LST: ...... 21:30h – 15:00h 8a. Description of the observing programme

Astrophysical context tion. In order to identify small RV variations as caused by possible sub-stellar companions, and accurately de- Since the discovery of the first exoplanet, the effort to termine spectral types, ∼6 data points per target are find other planetary systems and Earth-twins steadily needed. increased and still does. In order to identify possible planet-hosting stars, large-scale surveys are of prime importance. Systematic transit surveys like HATNet Previous work [4], WASP [11], TrES [1] or the Corot and Kepler mis- So far, by analyzing 19 of the 49 monitored fields, sion [2, 7, 8] have demonstrated the high return in the HATSouth survey has identified 691 candidates for terms of planet discoveries. Transiting planets are a hosting a sub-stellar companion. A bit less than 50% of privileged category of planets as it is possible to mea- the candidates have reconnaissance observations from sure not only their dimension but, if precise radial ve- the ANU 2.3 m or WiFeS telescope, which allow the locity (RV) observations are added, also their mass. identification of false positives such as grazing eclips- In this way is possible to give some constraint on the ing binaries and giants. 118 objects have been ana- bulk composition and therefore obtain some hint on lyzed by RV follow-up measurements with FEROS so the formation history. The HATNet transit survey has far. Among these, 19 clearly show RV variations con- already identified 54 exoplanets (exoplanet.eu, Jun 3 sistent with being transiting planets (e.g. HATS-1 to 2014). The global southern counterpart of HATNet, -6, HATS552-017, HATS515-001). Additionally, 47% HATSouth [3, 5], started in 2010 to produce excit- of these and further ones have been followed-up pho- ing candidates, especially in the regime of relatively tometrically and spectroscopically with different tele- bright stars. The regime of bright stars is not well scopes and instruments by members of the collabora- covered by the Kepler project and are ideal target for tion. More candidates are expected to flow from the spectroscopic follow-up observations. HATSouth is a analysis of the remaining fields already observed, and transit network operated by Princeton University, Aus- from the more than 60 fields which are planned to be tralian National University (ANU), Pontificia Univer- monitored during the next five years. sidad Catolica de Chile (PUC) and MPIA with six sta- tions located in Chile, Namibia and Australia. It is the first homogeneous global network in the southern Layout of observations hemisphere, providing an unprecedented sensitivity to We plan to observe 17 targets during the ESO P94 pe- planets with orbital periods up to 50 days. One of the riod. To get a sufficient SNR of 50–70, we estimated an challenges of transit surveys is to confirm the plane- exposure time of ∼ 15 minutes for a V ≈11 mag star tary nature as the origin of the photometric-transits (average of target magnitudes) with a typical seeing events and to exclude false positives such as grazing of 1–1.4 arcsec for the reconnaissance target, while a eclipsing binaries and variable stars. This implies that longer time (up to ≈60 minutes for the faint targets) is RV follow-up observations are essential. Moreover, the needed for the high precision RV measurements. Spec- additional spectroscopic analysis can provide system tra will be obtained in the Object-Calibration mode information like spectral type and binarity. We have of FEROS. The data will be first reduced with the confirmed more than a dozen extra-solar planets so far. FEROS pipeline at the telescope (MIDAS). The RV Five of these have been published (HATS-1b, -2b, -3b, computation will be performed by cross-correlating the -4b, and -5b; [16], [6], [12], [19] and [11], see Fig. 1 and object spectra with a matching synthetic one chosen 2), a couple is close to submission (e.g. [11]), and the on background of the spectral type analysis with Spec- others are under analysis. troscopy Made Easy (SME) [18]. The observations are part of the Ph.D. thesis of Simona Ciceri. A proposal Immediate aim by L. Mancini to follow-up candidates with GROND is handed-in. 1. Constraining orbital solutions for 9 objects: For 9 targets some FEROS high precision RV measure- ments are available. These reveal a clear variability and Strategic importance for MPIA low RV errors. Some of them have been photometri- This program is of high strategic importance for the cally followed-up as well (e.g. HATS602-010 is Fig. 3). MPIA. Since the HAT-South transit survey is a collab- We need for each of these targets ∼ 10 extra RV-data oration among the MPIA, Princeton, PUC and ANU, points to constrain the orbital solution and call out it is necessary that the MPIA confirms its status of them as exoplanets. being a dedicated partner of this project. Furthermore 2. Identifying RV variability for 8 targets with follow-up observations for transit survey candidates are a promising detection light curve: We now have crucial and the FEROS spectrograph at the ESO/MPG several dozens of candidates for which a promising de- 2.2 m telescope at La Silla is one of the few suitable in- tection light curve is available. To discard false positive struments on the southern hemisphere. events is necessary to properly identify the host star’s spectral class, and check for possible large RV varia-

2 8b. Figures and tables

Figure 1: Center of mass high precision RV mea- surements of HATS-4b obtained with FEROS (Xs), Figure 2: Center-of-mass corrected RV measurements CORALIE (filled circles), Subaru/HDS (filled trian- with the Magellan/PFS (dark filled circles) and Sub- gles) and PSF (filled squares) as function of orbital aru/HDS (open triangles) as function of orbital phase phase with best-fitting model. Zero phase corresponds with best-fitting model for the system HATS-5. Zero to the time of mid-transit. The residual (O-C) and phase corresponds to the time of mid-transit. The bisector spans (BS) are displayed underneath [12]. residual (O-C) and bisector spans (BS) are displayed underneath [19]. Initial observations with FEROS were crucial to identifying the low-amplitude orbital varia- tion due to this Saturn-mass planet, and promoting this target for observations with 6 and 8-m class tele- scopes.

Figure 3: Photometric follow-up light curves of HATS602-010. The data were collected using the 1.54 m Danish telescope in La Silla. Observation were carried out on March the 14th 2014. The orbital varia- tion due to the planet has been detected with FEROS and CORALIE.

3 8e. Current logistics of PhD thesis/long term programme

This proposal is linked to the PhD thesis of Simona analysis will be done using SME [18], and other tools Ciceri. The topic of her thesis is ‘Characterizing extra- like BinMag [13]. The spectral type is not only a signi- solar planets’, and deals with identification and con- cant system parameter (it allows to improve the radial firmation of new exoplanets, and characterization of velocity results through the correct choose of simulated known transiting exoplanetary systems. Regarding the spectrum for cross-correlation), but also allows to rule first aim, she is involved in two different projects: the out giants from the list of candidates. Giants are not HATSouth project and the the CAHA-MPIA collab- expected to host extrasolar planets at such short peri- oration for the project Radial velocity study of Ke- ods due to their large radii. Such potential sub-stellar pler exoplanet candidates. In the HATSouth collabora- signals are typically false positives, e.g. eclipsing bina- tion the main goal is confirm the HATSouth planetary ries blended with the light of a giant star. candidate via radial velocity measurements. Observa- All of the data reduction and analysis will be done by tions are carried out with the FEROS spectrograph and S. Ciceri, as one of the main tasks of her PhD thesis. data are subsequently analyzed through already exist- ing pipelines in order to find periodical variations due Logistics of observations to the presence of a planet. The reduction and analysis of the stellar spectra will lead to the characterization As already described in section 8a, almost 700 tar- of the host stars and will produce radial velocity curves gets have been identified by the HAT-South transit that can be examined to derive the masses of the com- survey and many more will be available during the panions. Since FEROS is the only planet search spec- next months. The quality of the photometric data trograph in the southern hemisphere accessible directly allowed the determination of their period and the through MPIA, the use of FEROS is essential for this subsequent phase folding. The photometric periods of PhD work. the targets listed in this proposal range between ∼0.64 (HATS606-027) and ∼34.67 days (HATS554-062). Logistics of data reduction and analysis The two categories of objects planned to be observed and analyzed are the following (see 8a): Reduction of the data will be done with the standard Category 1: 9 objects with promising detection Data Reduction System (DRS) of FEROS. Due to the light curves and some FEROS RV data points which optimized observing strategy and to the stability of show clearly a variability and low RV errors (one the telescope and the instrument, the accuracy is suf- with successful photometric follow-up measurements ficient for the tasks. In order to reveal signals of sub- obtained with the DK 1.54m telescope. Fig.3). stellar companions in systems with these targets, the Category 2: 8 objects with a promising detection RV has to be analyzed. The RV will be computed light curve and no FEROS RV data points so far. using the cross-correlation technique. The observed For a couple of object, previous reconnaissance obser- stellar spectrum will be cross-correlated with a syn- vations show no signs of false positives such as grazing thetic spectrum, generated with the program SPEC- eclipsing binaries or giants. TRUM by Richard O. Gray that matches the spectral type of the target, which has been determined with Spectroscopy made easy (SME) [18]. This computa- tion will be done with an IDL pipeline. The resulting cross-correlation function (CCF) is an average line pro- file of all used spectral lines (typically a few hundred). We can also determine the projected rotational veloc- ity v sin i from the width and the RV from the minima of the function. Additionally, the bisector of the CCF (= deformation of the line shape) can be determined as a supplemental parameter [17]. This parameter is very important for identifying subtle blended eclipsing bi- nary systems where dilution from a bright star results in light curves and RV curves that resemble those due to a transiting planet system. Additionally, RV varia- tions may be induced by stellar activity or non-radial pulsations [9], which may complicate the analysis of the system. Therefore, additional indicators such as shape and equivalent width of different spectral lines like CaII, Hα and Hβ have to be analyzed. Furthermore the systems will be analyzed in terms of spectral parameters including effective temperature Teff , surface gravity log g and metallicity [M/H]. This

4 9. Objects to be observed

(Objects to be observed with high priority should be marked in last column)

magnitude in Designation α (2000) δ (2000) spectral range priority to be observed

Category 1: HATS602-030 7h 29m 00s.00 −28◦ 250 00.000 11.97 C, D∗,E HATS555-012 7h 33m 00s.00 −25◦ 580 00.000 12.45 C, D∗,E HATS602-010 7h 16m 00s.00 −31◦ 140 00.000 12.57 C, D∗,E HATS606-010 9h 37m 00s.00 −29◦ 480 00.000 12.92 D, E∗,F HATS563-014 11h 24m 00s.00 −25◦ 200 00.000 12.95 E, F∗ HATS551-012 5h 30m 00s.00 −21◦ 460 00.000 13.01 B, C∗,D HATS554-024 7h 10m 00s.00 −20◦ 030 00.000 13.03 C, D∗,E HATS602-022 7h 17m 00s.00 −31◦ 090 00.000 13.45 C, D∗,E HATS554-051 7h 14m 00s.00 −25◦ 380 00.000 13.55 C, D∗,E

Category 2: HATS586-002 22h 57m 00s.00 −20◦ 160 00.000 8.225 A∗,B HATS606-006 9h 27m 00s.00 −27◦ 280 00.000 9.502 D, E∗,F HATS588-005 23h 58m 00s.00 −29◦ 360 00.000 10.906 A∗,B HATS606-016 9h 36m 00s.00 −27◦ 110 00.000 11.189 D, E∗,F HATS606-027 9h 27m 00s.00 −33◦ 390 00.000 11.317 D, E∗,F HATS632-001 23h 41m 00s.00 −32◦ 030 00.000 11.423 A∗,B HATS607-002 9h 52m 00s.00 −31◦ 400 00.000 11.938 D, E∗,F HATS554-062 7h 05m 00s.00 −22◦ 370 00.000 13.539 C, D∗,E

comments to tablea

a ∗: these are the periods in which the object is best visible Letter A to F: At each month from October to March is assigned a letter respectively from A to F. Category 1–3: An explanation of the different categories see 8a (Immediate Aim)

5 10. Justification of the amount of observing time requested:

The objects of category 1 already have some data points. In order to derive a preliminary orbital solution we propose 10 data points per object. With an execution time of 45 min in average, and including 5 min overhead (to get a S/N of 50–80 for the average visual magnitude of V≈12.8 mag) we need in total 67 hrs for these 9 targets. The 8 objects of category 2 have promising detection and follow-up photometry. In order to look for RV variability and further RV periodicity at least ∼6 data points are needed per target. This results in 16 hrs in total and, summed up with the time for category 1, in 83 hrs for the whole proposal. 11. Constraints for scheduling observations for this application:

Scheduling constraints for objects of category 1: These 9 objects with already some data points reveal all photometric periods between ∼1.89 d (HATS602-010) and ∼12.12 d (HATS602-022). Hence they should be observed ∼5 times during 10 consecutive nights. In order to be able to get data points in the areas of the phase covered by daylight during this time, the remaining 5 data points should be taken during another period of consecutive nights after a break of a few weeks. There are no scheduling constraints for the targets of category 2. Different observation schedules than those listed above will also be useful to optimize the phase coverage for all targets of category 1 but will risk having redundant data points. Anyway our candidates have a wide spread in RA and DEC, and thus we can observe some candidates at any given time. 12. Observational experience of observer(s) named under 2.3: (at least one observer must have sufficient experience) Simona Ciceri has good observing experience of RV measurements and planetary transits with the CAHA 1.23m and 2.2m, Cassini 1.52m, Danish 1.54m and the MPG/ESO 2.2m Telescopes.

Luigi Mancini is an expert observer with medium-class telescopes. He has already observed several times with the 2.5m INT, the CAHA 1.23m and 2.2m, the MPG/ESO 2.2m, the 1.54m Danish Telescope and the OAB 1.52m Cassini Telescope. 13. Observing runs at the ESO 2.2m-telscope (preferably during the last 3 years) and publications resulting from these Telescope instrument date hours success rate publications 2.2m FEROS Apr 11 - Sep 11 126 hrs 90% [15], [16], [14] 2.2m FEROS Oct 11 - Mar 12 131 hrs 90% [16], [14] 2.2m FEROS Apr 12 - Sep 12 149 hrs 100% [16], [14], [6] 2.2m FEROS Oct 12 - Mar 13 152 hrs 100% [16], [14], [6], [21] 2.2m FEROS Apr 13 - Sep 13 77 hrs 100% [6], [17], [12], [20] 2.2m FEROS Oct 13 - Mar 14 77 hrs 80% [6], [18], [12], [11]

6 14. References for items 8 and 13: [1] Alonso, Brown, Torres, Latham et al. (2004): TrES-1: The Transiting Planet of a Bright K0 Star, ApJ, 613, L153-L156

[2] Auvergne, M., Bodin, P., Boisnard, L., et al. (2009): The CoRoT satellite in flight:description and performance, A&A, 506, 411A

[3] Bakos, Afonso, Henning, Jordan, Holman et al. (2008): HAT-South: A Global Network of Southern Hemisphere Autmated Telescopes to Detect Transiting Exoplanets, Proceedings IAU Symposium No. 253, 2008

[4] Bakos, Hartman, Torres et al. (2011): Planets from the HATNet project, conference proceedings at the ”Detection and dynamics of transiting exoplanets”, Observatoire de Haute-Provence, 2010 August 23-27, 2011arXiv1101.0322B

[5] Bakos, G., Csubry, Z., Penev, K. et al. (2012): HATSouth: a global network of fully automated identical wide-field telescopes, PASP

[6] Bayliss, D., Zhou, G., Penev, K., Bakos, G. et al. (2013): HATS-3b: An inflated hot Jupiter transiting an F-type star, AJ, 146,13

[7] Batalha, N. M., Rowe, J. F. at al. (2013): Planetary Candidates Observed by Kepler, III: Analysis of the First 16 Months of Data, ApJS, 204, 24B

[8] Borucki, W. J., Koch, D. & Kepler Science Team (2010): Kepler Planet Detection Mission: Highlights of the First Results, AAS/Division for Planetary Sciences Meeting Abstracts #42, 42, 1052

[9] Christian, Pollacco, Skillen, Irwin et al. (2006): The WASP project in the era of robotic telescope networks, Astronomische Nachrichten, Vol.327, Issue 8, p.800

[10] Hatzes, A. (1996): Simulations of stellar radial velocity and spectral line bisector variations: I. nonradial pulsations, PASP, 108, 839

[11] Hartman, J. et al., HATS-6b, in prep.

[12] Jordan, A., Brahm, R., Bakos,G., et al., HATS-4b: a dense Hot Jupiter transiting a super metal rich G star, accepted for pubblication in AJ

[13] Kochukhov, O. BinMag: http://www.astro.uu.se/ oleg/

[14] Mohler-Fischer, M., Mancini, L., Henning, T., Nikolov, N. et al.(2013): HATS-2b: a transiting extrasolar planet orbiting a K-type star showing star spot activity,A&A, 558,A55

[15] Mohler, M., Setiawan, J., Launhardt, R. et al., in prep.

[16] Penev, Bakos, Bayliss, Jordan, Mohler et al. (2013):HATS-1b: The First Transiting Planet Discovered by the HATSouth Survey, AJ, 145, 5

[17] Santos, N. (2002): New studies on stars with giant planets, PhD thesis, University of Geneva

[18] Valenti, J. A. & Piskunov, N. (1996): Spectroscopy made easy: A new tool for fitting observations with synthetic spectra., AAPS, 118, 595

[19] Zhou, G., Bayliss, D., Penev, K., et al., HATS-5b: a transiting Hot Saturn from the HATSouth Survey, AJ, 147, 144

[20] Zhou, G., Bayliss, D., Hartman, J.D., et al. (2014) The Mass-Radius Relationship for Very Low Mass Stars: Four New Discoveries from the HATSouth Survey, MNRAS, 437, 2831

7 Tolerance limits for planned observations: maximum seeing: 200 minimum transparency: 60% maximum airmass: 1.8 photometric conditions: no moon: max. phase / 6 : 25◦ min. / max. lag: 0/0 nights