CHARACTERIZATION OF THE K2-19 MULTIPLE-TRANSITING PLANETARY SYSTEM VIA HIGH-DISPERSION SPECTROSCOPY, AO IMAGING, AND TRANSIT TIMING VARIATIONS
- Astrobiology Center, 2-21-1 Osawa, Mitaka, Tokyo, 181-8588 (Japan)
- Department of Earth and Planetary Sciences, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551 (Japan)
- Okayama Astrophysical Observatory, National Astronomical Observatory of Japan, Asakuchi, Okayama 719-0232 (Japan)
- Department of Astronomy, University of California, Berkeley, CA 94720 (United States)
- Department of Physics, and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)
- National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo, 181-8588 (Japan)
- Subaru Telescope, 650 North A’ohoku Place, Hilo, HI 96720 (United States)
- Institut d’Astrophysique et de Géophysique, Université de Liège, Allée du 6 Août 17, Bat. B5C, B-4000 Liège (Belgium)
- Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL (United Kingdom)
- Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States)
- SOKENDAI (The Graduate University for Advanced Studies), 2-21-1 Osawa, Mitaka, Tokyo, 181-8588 (Japan)
K2-19 (EPIC201505350) is an interesting planetary system in which two transiting planets with radii ∼7 R{sub ⊕} (inner planet b) and ∼4 R{sub ⊕} (outer planet c) have orbits that are nearly in a 3:2 mean-motion resonance. Here, we present results of ground-based follow-up observations for the K2-19 planetary system. We have performed high-dispersion spectroscopy and high-contrast adaptive-optics imaging of the host star with the HDS and HiCIAO on the Subaru 8.2 m telescope. We find that the host star is a relatively old (≥8 Gyr) late G-type star (T{sub eff} ∼ 5350 K, M{sub s} ∼ 0.9 M{sub ⊙}, and R{sub s} ∼ 0.9 R{sub ⊙}). We do not find any contaminating faint objects near the host star that could be responsible for (or dilute) the transit signals. We have also conducted transit follow-up photometry for the inner planet with KeplerCam on the FLWO 1.2 m telescope, TRAPPISTCAM on the TRAPPIST 0.6 m telescope, and MuSCAT on the OAO 1.88 m telescope. We confirm the presence of transit timing variations (TTVs), as previously reported by Armstrong and coworkers. We model the observed TTVs of the inner planet using the synodic chopping formulae given by Deck and Agol. We find two statistically indistinguishable solutions for which the period ratios (P{sub c}/P{sub b}) are located slightly above and below the exact 3:2 commensurability. Despite the degeneracy, we derive the orbital period of the inner planet P{sub b} ∼ 7.921 days and the mass of the outer planet M{sub c} ∼ 20 M{sub ⊕}. Additional transit photometry (especially for the outer planet) as well as precise radial-velocity measurements would be helpful to break the degeneracy and to determine the mass of the inner planet.
- OSTI ID:
- 22521794
- Journal Information:
- Astrophysical Journal, Vol. 815, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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