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

    Fingerprint

    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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