Time Allocation Committee for Application No. MPG time at the ESO 2.2m-telescope c/o MPI f¨urAstronomie Observing period April 2013 K¨onigstuhl17 Received D-69117 Heidelberg / Germany

APPLICATION FOR OBSERVING TIME

from X MPIA MPG institute other

1. Telescope: 2.2-m X 092.A-9008(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 spectrosopic follow- up observations with FEROS for 18 high-priority transit candidates from the HATSouth survey. These candidates include several with orbital periods longer than 10 days, and with radii in the Neptune-regime; all of these candidates are 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 their masses, radii, and orbital eccentricities.

4. Instrument: WFI X FEROS GROND

5. Brightness range of objects to be observed: from 8.23 to 14.02 V-mag

6. Number of hours: applied for already awarded still needed 79 450 300 no restriction grey dark

7. Optimum date range for the observations: ...... 1.04.2014 – 30.09.2014 Usable range in local sideral time LST: ...... 8:15h – 5:10h 8a. Description of the observing programme

Astrophysical context per target. 3. Identifying RV variability for 7 targets with Since the discovery of the first exoplanet, the effort to a promising detection light curve: For 7 targets a find exoplanetary systems steadily increased and still promising detection light curve is available. For some does. In order to identify possible planet-hosting stars, of the candidates additional reconnaissance observa- large-scale surveys are of prime importance. System- tions with low-resolution spectrographs already deter- atic transit surveys like HATNet [3], WASP [9], TrES mined the nature of the possible host stars as slowly [1] and the Kepler mission [7, 8, 6] have demonstrated rotating dwarfs without large RV variations. In order the high return in terms of planet discoveries. Transit- to identify small RV variations, as caused by possi- ing planets are of particular interest because in addi- ble sub-stellar companions, and accurately determine tion to measuring their radius with the transit method, spectral types, ∼7 data points per target are needed. we can also determine their mass, if precise radial ve- locity (RV) observations are added. The HATNet tran- sit survey has already identified 48 exoplanets (exo- Previous work planet.eu, Nov 8 2013). The global southern counter- So far, by analysing 15 of the 37 monitored fields, the part of HATNet, HATSouth [2, 4], started in 2010 to HASouth survey has identified 547 candidates for host- produce exciting candidates, especially in the regime ing a substellar companion. 39% of the candidates have of relatively bright stars. The regime of bright stars reconnaissance observations from the ANU 2.3 m tele- is not well covered by the Kepler project and are ideal scope, which allow the identification of false positives target for spectroscopic follow-up observations. HAT- such as grazing eclisping binaries and giants. 75 objects South is a transit network operated by Princeton Uni- have been analysed by RV follow-up measurements versity, Australian National University (ANU), Ponti- with FEROS so far. Additionally, 60% of these and fur- ficia Universidad Catolica de Chile (PUC) and MPIA ther ones have been followed-up photometrically and with three stations in Chile, Namibia and Australia. It spectroscopically with different telescopes and instru- is the first homogeneous global network in the south- ments by members of the collaboration. More can- ern sky. One of the challenges of transit surveys is to didates are expected to flow from the analysis of the confirm the planetary nature as the origin of the pho- remaining 22 fields, already observed, and from the tometric -transits events and to exclude false positives more than 60 fields which are planned to be monitored such as grazing eclipsing binaries and variable stars. during the next five years. This implies that RV follow-up observations are essen- tial. Except in the rare case of multi-transiting-planet systems, RV measurements are the only way to measure Layout of observations the masses of transiting planets. The additional spec- We plan to observe 18 targets during the ESO P93 troscopic analysis can provide system information like period. The long-term stability of FEROS has been spectral type and binarity. We have confirmed more proved over the last 8 years to be 10 m/s [13]. Spec- than a dozen extra-solar planets so far. Three of these tra will be obtained in the Object-Calibration mode have been published (HATS-1b, -2b, and -3b; [15],[12] of FEROS. The data will be first reduced with the and [5], Fig. 1), two are being finalized for submission FEROS pipeline at the telescope (MIDAS). The RV ([18], [11], see fig. 2.), and the others are undergoing computation will be performed by cross-correlating the analysis. object spectra with a matching synthetic one chosen on background of the spectral type analysis with Spec- Immediate aim troscopy Made Easy (SME) [17]. The observations are part of the Ph.D. thesis of Simona Ciceri. A proposal 1. Constraining orbital solutions for 5 ob- by L. Mancini to follow-up candidates with GROND is jects with matching RV and photometric pe- handed-in. riod: Follow-up observations of 5 targets for which several FEROS data points are available and the deter- mined RV period is in good agreement with the pho- Strategic importance for MPIA tometric one. Some of them have been successfully This program is of high strategic importance for the followed-up photometrically as well (e.g. HATS582- MPIA. Since the HAT-South transit survey is a collab- 006 is Fig. 3). We need for each of these targets ∼ 10 oration among the MPIA, Princeton, PUC and ANU, extra RV-data points to constrain the orbital solution it is necessary that the MPIA confirms its status of and call out them as exoplanets. being a dedicated partner of this project. Furthermore 2. Identifying RV periodicity of 6 objects: For follow-up observations for transit survey candidates are 6 of the targets only a few high precision RV measure- crucial and the FEROS spectrograph at the ESO/MPG ments are available. These reveal a clear variability 2.2 m telescope at La Silla is one of the few suitable in- and low RV errors. In order to identify RV periodicity struments on the southern hemisphere. and crosscheck them with the detection period in the photometric data, we need ∼7 additional data points

2 8b. Figures and tables

Figure 2: Center-of-mass corrected RV measurements with the Magellan/PFS (dark filled circles) and Sub- aru/HDS (open triangles) as function of orbital phase with best-fitting model for the system HATS-5. Zero phase corresponds to the time of mid-transit. The residua are displayed underneath [18]. Initial observa- tions with FEROS were crucial to identifying the low- amplitude orbital variation due to this Saturn-mass planet, and promoting this target for observations with 6 and 8-m class telescopes.

Figure 1: Center-of-mass corrected RV measurements of HATS-3b obtained with FEROS (open triangles), CORALIE (filled circles) and CYCLOPS (filled tri- angles) as function of orbital phase with best-fitting model. Zero phase corresponds to the time of mid- transit. The residua are displayed underneath [5].

Figure 3: Photometric follow-up light curves of HATS582-006 obtained simultaneously in four optical bands (g, r, i, z). The data were collected using the GROND instrument on the 2.2 m MPG telescope in La Silla. Observation were carried out on June the 12th 2013. The orbital variation due to the planet has been detected with FEROS.

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 [17], and other tools Ciceri. The topic of her thesis is ‘Characterizing extra- like BinMag [12]. The spectral type is not only a sig- solar planets’, and deals with identification and con- nificant system parameter and will improve the radial firmation of new exoplanets, and characterization of velocity results by helping to choose the right simu- known transiting exoplanetary systems. Regarding the lated spectrum for cross-correlation, but will also allow first aim, she is involved in two different projects: the to rule out giants from the sample. Giants are not ex- HATSouth project and the the CAHA-MPIA collab- pected to host extrasolar planets at such short periods oration for the project Radial velocity study of Ke- due to their large radii. Such potential sub-stellar sig- pler exoplanet candidates. In the HATSouth collabora- nals are typically false positives, e.g. eclipsing binaries tion the main goal is confirm the HATSouth planetary 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, more than 500 of the host stars and will produce radial velocity curves targets 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 emisphere 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 ∼0.5 (HATS568-003) and ∼18 days (HATS585-008). Logistics of data reduction and analysis The three categories of objects planned to be observed and analysed as part of this PhD thesis are the Reduction of the data will be done with the standard following (see 8a): Category 1: 5 objects with Data Reduction System (DRS) of FEROS. Due to the promising detection light curves and some FEROS optimized observing strategy and to the stability of RV data points which revealed the same period as the telescope and the instrument, the accuracy is suf- the photometric light curve (one with successful ficient for the tasks. In order to reveal signals of sub- photometric follow-up measurements obtained with stellar companions in systems with these targets, the GROND), Category 2: 6 objects with a promising RV has to be analyzed. The RV will be computed detection light curve and few FEROS RV data points using the cross-correlation technique. The observed which show clearly a variability and low RV errors and stellar spectrum will be cross-correlated with a syn- Category 3: 7 objects with a promising detection thetic spectrum, generated with the program SPEC- light curve and no FEROS RV data points so far. TRUM by Richard O. Gray that matches the spectral Reconnaissance observations of all targets listed in type of the target, which has been determined with this proposal show no signs of false positives such as Spectroscopy made easy (SME) [17]. This computa- grazing eclipsing binaries or giants. 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 [16]. 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 [10], 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: HATS563-002 11h 21m 00s.00 −22◦ 230 00.000 13.93 A∗, B, C HATS563-034 11h 44m 00s.00 −22◦ 090 00.000 13.92 A∗, B, C HATS579-007 19h 17m 00s.00 −23◦ 500 00.000 13.09 B, C, D∗, E, F HATS582-006 20h 52m 00s.00 −25◦ 410 00.000 14.02 B, C, D∗, E, F HATS563-014 11h 24m 00s.00 −25◦ 200 00.000 12.95 A∗,B

Category 2: HATS579-019 19h 17m 00s.00 −22◦ 230 00.000 13.93 B, C, D, E∗,F HATS579-026 19h 37m 00s.00 −22◦ 120 00.000 12.99 B, C, D, E∗,F HATS626-003 20h 19m 00s.00 −26◦ 340 00.000 13.40 B, C, D, E∗,F HATS585-008 22h 41m 00s.00 −20◦ 290 00.000 13.54 C, D, E∗,F HATS579-038 19h 42m 00s.00 −26◦ 050 00.000 13.76 B, C, D, E∗,F HATS585-006 22h 22m 00s.00 −19◦ 470 00.000 13.94 C, D, E∗,F

Category 3: HATS586-002 22h 57m 00s.00 −20◦ 160 00.000 8.23 D, E∗,F HATS606-006 09h 27m 00s.00 −27◦ 280 00.000 9.50 A∗,B HATS606-036 09h 21m 00s.00 −33◦ 130 00.000 10.18 A∗,B HATS606-021 09h 41m 00s.00 −31◦ 490 00.000 11.18 A∗,B HATS606-016 09h 36m 00s.00 −27◦ 110 00.000 11.19 A∗,B HATS606-027 09h 27m 00s.00 −33◦ 390 00.000 11.32 A∗,B HATS568-003 13h 49m 00s.00 −23◦ 430 00.000 11.55 A∗, B, C

comments to tablea

a ∗: these are the periods in which the object is best visible Letter A to F: At each month from April to September 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 40 min including 5 min overhead (to get a S/N of 30–50 for the average visual magnitude of V≈13.6 mag) we need in total 38 hrs for these seven targets. The six objects of category 2 have a couple of high-precision RV data points that clearly reveal a RV variability. In order to identify a period, additional ∼7 data points per target with the same execution time as above are needed. That results in 24 hrs in total. The 7 objects of category 3 have promising detection and follow-up photometry. In order to look for RV variability and further RV periodicity ∼7 data points are needed per target. This results in 17 hrs in total and, summed up with the time for category 1 and 2, in 79 hrs for the whole proposal. 11. Constraints for scheduling observations for this application:

Scheduling constraints for objects of category 1: These 5 objects with already some data points reveal all photometric periods between ∼2.08 d (HATS579-007) and ∼8.56 d (HATS563-014). Hence they should be observed ∼5 times during 9 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 9 consecutive nights after a break of a few weeks. There are no scheduling constraints for the targets of category 2 and 3. 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 2.2m, the MPG/ESO 2.2m, the 1.54m Danish Telescope, the OAB 1.52m Cassini Telescope, and the CAHA 1.23m 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% [14], [15], [13] 2.2m FEROS Oct 11 - Mar 12 131 hrs 90% [15], [13] 2.2m FEROS Apr 12 - Sep 12 149 hrs 100% [15], [13], [5] 2.2m FEROS Oct 12 - Mar 13 152 hrs 100% [15], [13], [5], [19] 2.2m FEROS Apr 13 - Sept 13 77 hrs 100% [5], [18], [11], [19]

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] 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

[3] 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

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

[5] 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

[6] 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

[7] 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

[8] Borucki, W. J., Koch, D. G. at al. (2011): Characteristics of Planetary Candidates Observed by Kepler. II. Analysis of the First Four Months of Data, ApJ, 736,19

[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] Jordan, A. et al., HATS-4b, in prep.

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

[13] 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

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

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

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

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

[18] Zhou, G. et al., HATS-5b, in prep.

[19] Zhou, G., Bayliss, D., Hartman, J.D., et al. (2013) The Mass-Radius Relationship for Very Low Mass Stars: Four New Discoveries from the HATSouth Survey, accepted for publication in MNRAS

7 Tolerance limits for planned observations: maximum seeing: 200 minimum transparency: 60% maximum airmass: 1.8 photometric conditions: no moon: max. phase / 6 : 1/10◦ min. / max. lag: 0/0 nights