Transit confirmation and improved stellar and planet parameters for the super-Earth HD 97658 b and its host star

V. Van Grootel, M. Gillon, D. Valencia, N. Madhusudhan, D. Dragomir, A. R. Howe, Adam S. Burrows, B. O. Demory, D. Deming, D. Ehrenreich, C. Lovis, M. Mayor, F. Pepe, D. Queloz, R. Scuflaire, S. Seager, D. Segransan, S. Udry

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Abstract

Super-Earths transiting nearby bright stars are key objects that simultaneously allow for accurate measurements of both their mass and radius, providing essential constraints on their internal composition. We present here the confirmation, based on Spitzer transit observations, that the super-Earth HD 97658 b transits its host star. HD 97658 is a low-mass (M * = 0.77 ± 0.05 M ) K1 dwarf, as determined from the Hipparcos parallax and stellar evolution modeling. To constrain the planet parameters, we carry out Bayesian global analyses of Keck-High Resolution Echelle Spectrometer (Keck-HIRES) radial velocities and Microvariability and Oscillations of STars (MOST) and Spitzer photometry. HD 97658 b is a massive () and large ( at 4.5 μm) super-Earth. We investigate the possible internal compositions for HD 97658 b. Our results indicate a large rocky component, of at least 60% by mass, and very little H-He components, at most 2% by mass. We also discuss how future asteroseismic observations can improve the knowledge of the HD 97658 system, in particular by constraining its age. Orbiting a bright host star, HD 97658 b will be a key target for upcoming space missions such as the Transiting Exoplanet Survey Satellite (TESS), the Characterizing Exoplanet Satellite (CHEOPS), the Planetary Transits and Oscillations of stars (PLATO), and the James Webb Space Telescope to characterize thoroughly its structure and atmosphere.

Original languageEnglish (US)
Article number2
JournalAstrophysical Journal
Volume786
Issue number1
DOIs
StatePublished - May 1 2014

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • binaries: eclipsing
  • planetary systems
  • stars: individual (HD 97658)
  • techniques: photometric
  • techniques: radial velocities

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    Van Grootel, V., Gillon, M., Valencia, D., Madhusudhan, N., Dragomir, D., Howe, A. R., Burrows, A. S., Demory, B. O., Deming, D., Ehrenreich, D., Lovis, C., Mayor, M., Pepe, F., Queloz, D., Scuflaire, R., Seager, S., Segransan, D., & Udry, S. (2014). Transit confirmation and improved stellar and planet parameters for the super-Earth HD 97658 b and its host star. Astrophysical Journal, 786(1), [2]. https://doi.org/10.1088/0004-637X/786/1/2