Planetary transit observations at the University Observatory Jena: TrES-2

📝 Abstract

We report on observations of several transit events of the transiting planet TrES-2 obtained with the Cassegrain-Teleskop-Kamera at the University Observatory Jena. Between March 2007 and November 2008 ten different transits and almost a complete orbital period were observed. Overall, in 40 nights of observation 4291 exposures (in total 71.52 h of observation) of the TrES-2 parent star were taken. With the transit timings for TrES-2 from the 34 events published by the TrES-network, the Transit Light Curve project and the Exoplanet Transit Database plus our own ten transits, we find that the orbital period is P=(2.470614 +/- 0.000001) d, a slight change by ~0.6 s compared to the previously published period. We present new ephemeris for this transiting planet. Furthermore, we found a second dip after the transit which could either be due to a blended variable star or occultation of a second star or even an additional object in the system. Our observations will be useful for future investigations of timing variations caused by additional perturbing planets and/or stellar spots and/or moons.

💡 Analysis

We report on observations of several transit events of the transiting planet TrES-2 obtained with the Cassegrain-Teleskop-Kamera at the University Observatory Jena. Between March 2007 and November 2008 ten different transits and almost a complete orbital period were observed. Overall, in 40 nights of observation 4291 exposures (in total 71.52 h of observation) of the TrES-2 parent star were taken. With the transit timings for TrES-2 from the 34 events published by the TrES-network, the Transit Light Curve project and the Exoplanet Transit Database plus our own ten transits, we find that the orbital period is P=(2.470614 +/- 0.000001) d, a slight change by ~0.6 s compared to the previously published period. We present new ephemeris for this transiting planet. Furthermore, we found a second dip after the transit which could either be due to a blended variable star or occultation of a second star or even an additional object in the system. Our observations will be useful for future investigations of timing variations caused by additional perturbing planets and/or stellar spots and/or moons.

📄 Content

arXiv:0905.1842v1 [astro-ph.EP] 12 May 2009 Astron. Nachr. / AN 999, No. 88, 789 – 798 (2006) / DOI please set DOI! Planetary transit observations at the University Observatory Jena: TrES-2⋆ St. Raetz1,⋆⋆, M. Mugrauer1, T. O. B. Schmidt1, T. Roell1, T. Eisenbeiss1, M. M. Hohle1,4, A. Koeltzsch1, M. Vaˇnko1, Ch. Ginski1, C. Marka1, M. Moualla1, N. Tetzlaff1, A. Seifahrt1,2, Ch. Broeg3, J. Koppenhoefer5, M. Raetz6, and R. Neuh¨auser1 1 Astrophysikalisches Institut und Universit¨ats-Sternwarte Jena, Schillerg¨aßchen 2-3, 07745 Jena, Germany 2 Institut f¨ur Astrophysik, Georg-August-Universit¨at, Friedrich-Hund-Platz 1, 37077 G¨ottingen, Germany 3 Space Research and Planetary Sciences, Physikalisches Institut, University of Bern, Sidlerstraße 5, 3012 Bern, Switzer- land 4 Max Planck Institute for Extraterrestrial Physics, Giessenbachstraße, 85748 Garching, Germany 5 University Observatory Munich, Scheinerstrasse 1, 81679 M¨unchen, Germany 6 Private observatory Raetz, Stiller Berg 6, 98587 Herges-Hallenberg, Germany Received 2008 Dec 9, accepted 2009 Apr 3 Published online 2009 May 30 Key words binaries: eclipsing — planetary systems — stars: individual (GSC03549-02811) — techniques: photometric We report on observations of several transit events of the transiting planet TrES-2 obtained with the Cassegrain-Telskop- Kamera at the University Observatory Jena. Between March 2007 and November 2008 ten different transits and almost a complete orbital period were observed. Overall, in 40 nights of observation 4291 exposures (in total 71.52 h of observation) of the TrES-2 parent star were taken. With the transit timings for TrES-2 from the 34 events published by the TrES- network, the Transit Light Curve project and the Exoplanet Transit Database plus our own ten transits, we find that the orbital period is P = (2.470614 ± 0.000001) d, a slight change by ∼0.6 s compared to the previously published period. We present new ephemeris for this transiting planet. Furthermore, we found a second dip after the transit which could either be due to a blended variable star or occultation of a second star or even an additional object in the system. Our observations will be useful for future investigations of timing variations caused by additional perturbing planets and/or stellar spots and/or moons. c ⃝2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1 Introduction TrES-2 is the second transiting hot Jupiter discovered by the Trans-atlantic Exoplanet Survey (TrES, O’Donovan et al. 2006). The planet orbits the nearby 11th magnitude G0 V main-sequence dwarf GSC 03549-02811 every ∼2.5 days. From high-resolution spectra, Sozzetti et al. (2007) derived accurate values of the stellar atmospheric parameters of the TrES-2 parent star such as effective temperature, surface gravity and metallicity. With the help of detailed analysis of high precision z-band photometry and light curve mod- eling of the 1.4% deep transit by the Transit Light Curve (TLC) Project (Holman et al. 2007), estimates of the plane- tary parameters could also be determined. One goal of the TLC project is to measure variations in the transit times and light curve shapes that would be caused by the influence of additional bodies in the system (Agol et ⋆Based on observations obtained with telescopes of the University Ob- servatory Jena, which is operated by the Astrophysical Institute of the Friedrich-Schiller-University Jena and the 80cm telescope of the Wendel- stein Observatory of the Ludwig-Maximilians-University Munich. ⋆⋆Corresponding author: e-mail: straetz@astro.uni-jena.de al. 2005; Holman & Murray 2005; Steffen & Agol 2005). The large impact parameter of TrES-2 makes the duration more sensitive to any changes. Hence, TrES-2 is an excel- lent target for the detection of long-term changes in tran- sit characteristics induced by orbital precession (Miralda- Escud´e 2002). We have started high precision photometric observations at the University Observatory Jena in fall 2006. In this work we use the transit method to observe the transiting planet TrES-2. We paid special attention to the accurate determi- nation of transit times in order to identify precise transit tim- ing variations that would be indicative of perturbations from additional bodies and to refine the orbital parameters of the system. First results were presented in Raetz et al. (2009a). TrES-2 lies within the field of view of the NASA Kepler mission (Borucki et al 2003; Basri et al 2005). During the four year mission, Kepler will observe nearly 600 transits of TrES-2 (O’Donovan et al. 2006). The precision of Kepler will be extremely sensitive to search for additional planets in the TrES-2 system through their dynamical perturbations. In this paper, we describe the observations, the data reduc- tion and the analysis procedures. Furthermore, we present c ⃝2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 790 St. Raetz et al.: Transit observation at the University Observatory Jena results for TrES-2 that we ob

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