Search for Close-in Planets around Evolved Stars with Phase-curve variations and Radial Velocity Measurements

Teruyuki Hirano, Bun'Ei Sato, Kento Masuda, Othman Benomar, Yoichi Takeda, Masashi Omiya, Hiroki Harakawa

Research output: Contribution to journalArticle

Abstract

Tidal interactions are a key process to understand the evolution history of close-in exoplanets. But tidals still have a large uncertainty in their prediction for the damping timescales of stellar obliquity and semi-major axis. We have worked on a search for transiting giant planets around evolved stars, for which few close-in planets were discovered. It has been reported that evolved stars lack close-in planets, which is often attributed to the tidal evolution and/or engulfment of close-in planets by the hosts. Meanwhile, Kepler has detected a certain fraction of transiting planet candidates around evolved stars. Confirming the planetary nature for these candidates is especially important since the comparison between the occurrence rates of close-in planets around main sequence stars and evolved stars provides a unique opportunity to discuss the final stage of close-in planets. With the aim of confirming KOI planet candidates around evolved stars, we measured precision radial velocities (RVs) for evolved stars with transiting planet candidates using Subaru/HDS. We also developed a new code which simultaneously models and fits the observed RVs and phase-curve variations in the Kepler data (e.g., transits, stellar ellipsoidal variations, and planet emission/reflected light). As a result of applying the global fit to KOI giants/subgiants, we confirmed two giant planets around evolved stars (Kepler-91 and KOI-1894), as well as revealed that KOI-977 is more likely a false positive.

Original languageEnglish (US)
Pages (from-to)63-64
Number of pages2
JournalProceedings of the International Astronomical Union
Volume11
Issue numberA29A
DOIs
StatePublished - Jan 1 2015

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velocity measurement
radial velocity
planets
planet
stars
curves
main sequence stars
obliquity
extrasolar planets
transit
damping
histories
occurrences
timescale

Keywords

  • KOI-1894
  • KOI-2133
  • planets and satellites: individual (KOI-977

ASJC Scopus subject areas

  • Astronomy and Astrophysics

Cite this

Search for Close-in Planets around Evolved Stars with Phase-curve variations and Radial Velocity Measurements. / Hirano, Teruyuki; Sato, Bun'Ei; Masuda, Kento; Benomar, Othman; Takeda, Yoichi; Omiya, Masashi; Harakawa, Hiroki.

In: Proceedings of the International Astronomical Union, Vol. 11, No. A29A, 01.01.2015, p. 63-64.

Research output: Contribution to journalArticle

Hirano, Teruyuki ; Sato, Bun'Ei ; Masuda, Kento ; Benomar, Othman ; Takeda, Yoichi ; Omiya, Masashi ; Harakawa, Hiroki. / Search for Close-in Planets around Evolved Stars with Phase-curve variations and Radial Velocity Measurements. In: Proceedings of the International Astronomical Union. 2015 ; Vol. 11, No. A29A. pp. 63-64.
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