Transit confirmation and improved stellar and planet parameters for the super-Earth HD 97658 b and its host star
- Institut d'Astrophysique et de Géophysique, Université de Liège, 17 Allée du 6 Août, B-4000 Liège (Belgium)
- Department of Physical and Environmental Sciences, University of Toronto, 1265 Military Trail, Toronto, ON, M1C 1A4 (Canada)
- Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)
- Las Cumbres Observatory Global Telescope Network, 6740 Cortona Dr. Suite 102, Goleta, CA 93117 (United States)
- Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)
- Department of Astronomy, University of Maryland, College Park, MD 20742-2421 (United States)
- Observatoire de Genève, Université de Genève, 51 Chemin des Maillettes, CH-1290 Sauverny (Switzerland)
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 {sub *} = 0.77 ± 0.05 M {sub ☉}) 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 (M{sub P}=7.55{sub −0.79}{sup +0.83} M{sub ⊕}) and large (R{sub P}=2.247{sub −0.095}{sup +0.098}R{sub ⊕} 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.
- OSTI ID:
- 22357050
- Journal Information:
- Astrophysical Journal, Vol. 786, 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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