Kavli Affiliate: Sara Seager
| First 5 Authors: Alejandro Hacker, Rodrigo F. Díaz, David J. Armstrong, Jorge Fernández Fernández, Simon Müller
| Summary:
We report the discovery of two transiting planets detected by the Transiting
Exoplanet Survey Satellite (TESS), TOI-2374 b and TOI-3071 b, orbiting a K5V
and an F8V star, respectively, with periods of 4.31 and 1.27 days,
respectively. We confirm and characterize these two planets with a variety of
ground-based and follow-up observations, including photometry, precise radial
velocity monitoring and high-resolution imaging. The planetary and orbital
parameters were derived from a joint analysis of the radial velocities and
photometric data. We found that the two planets have masses of $(57 pm 4)$
$M_oplus$ or $(0.18 pm 0.01)$ $M_J$, and $(68 pm 4)$ $M_oplus$ or $(0.21
pm 0.01)$ $M_J$, respectively, and they have radii of $(6.8 pm 0.3)$
$R_oplus$ or $(0.61 pm 0.03)$ $R_J$ and $(7.2 pm 0.5)$ $R_oplus$ or $(0.64
pm 0.05)$ $R_J$, respectively. These parameters correspond to sub-Saturns
within the Neptunian desert, both planets being hot and highly irradiated, with
$T_{rm eq} approx 745$ $K$ and $T_{rm eq} approx 1812$ $K$, respectively,
assuming a Bond albedo of 0.5. TOI-3071 b has the hottest equilibrium
temperature of all known planets with masses between $10$ and $300$ $M_oplus$
and radii less than $1.5$ $R_J$. By applying gas giant evolution models we
found that both planets, especially TOI-3071 b, are very metal-rich. This
challenges standard formation models which generally predict lower
heavy-element masses for planets with similar characteristics. We studied the
evolution of the planets’ atmospheres under photoevaporation and concluded that
both are stable against evaporation due to their large masses and likely high
metallicities in their gaseous envelopes.
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