CHARACTERIZATION OF THE K2-19 MULTIPLE-TRANSITING PLANETARY SYSTEM VIA HIGH-DISPERSION SPECTROSCOPY, AO IMAGING, AND TRANSIT TIMING VARIATIONS
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Narita-2015-CHARACTERIZATION OF.pdf
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Author(s)
Narita, Norio
Hirano, Teruyuki
Fukui, Akihiko
Hori, Yasunori
Sanchis-Ojeda, Roberto
Ryu, Tsuguru
Kusakabe, Nobuhiko
Kudo, Tomoyuki
Onitsuka, Masahiro
Delrez, Laetitia
Date Issued
December 2015
Journal
The Astrophysical Journal
Publisher
IOP Publishing
Citation
Narita, Norio, Teruyuki Hirano, Akihiko Fukui, Yasunori Hori, Roberto Sanchis-Ojeda, Joshua N. Winn, Tsuguru Ryu, et al. “CHARACTERIZATION OF THE K2-19 MULTIPLE-TRANSITING PLANETARY SYSTEM VIA HIGH-DISPERSION SPECTROSCOPY, AO IMAGING, AND TRANSIT TIMING VARIATIONS.” The Astrophysical Journal 815, no. 1 (December 8, 2015): 47. © 2015 The American Astronomical Society
Version
Final published version
Abstract
K2-19 (EPIC201505350) is an interesting planetary system in which two transiting planets with radii ~7 R[subscript ⊕] (inner planet b) and ~4 R[subscript ⊕] (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[subscript eff] ~ 5350 K, M[subscript s] ~ 0.9 M[subscript ⊙], and R[subscript s] ~ 0.9 R[subscript ⊙]). 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 & Agol. We find two statistically indistinguishable solutions for which the period ratios (P[subscript c]/P[subscript 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[subscript b] ~ 7.921 days and the mass of the outer planet M[subscript c] ~ 20 M[subscript ⊕]. 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.
MIT Department
Massachusetts Institute of Technology. Department of Physics
MIT Kavli Institute for Astrophysics and Space Research
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DOI of Published Version
https://doi.org/10.1088/0004-637x/815/1/47
