Kavli Affiliate: Saul A. Rappaport
| First 5 Authors: Victoria DiTomasso, Victoria DiTomasso, , ,
| Summary:
We present the discovery of the planetary system orbiting the bright (V =
7.2), nearby (35 pc), Sun-like star HD 60779, which has a mass of 1.050 +/-
0.044 solar masses and a radius of 1.129 +/- 0.013 solar radii. We report two
TESS transits and a subsequent CHEOPS transit of HD 60779 b, a sub-Neptune with
a radius of 3.250 (+0.100 / -0.098) Earth radii on a 29.986175 (+0.000030 /
-0.000033) day orbit. Additionally, 286 HARPS-N radial velocity measurements
reveal the mass of planet b (14.7 +1.1 / -1.0 Earth masses) and the presence of
an outer planet, HD 60779 c, with an orbital period of 104.25 (+0.30 / -0.29)
days and a minimum mass (m sin i) of 27.7 +/- 1.6 Earth masses. Both planets’
orbits are consistent with being circular, suggesting that they have a
dynamically quiet history. The data are not sufficient to determine whether
planet c transits. HD 60779’s uniquely high systemic radial velocity (129.75
+/- 0.12 km/s) allows its Lyman-alpha emission to avoid absorption by the
interstellar medium, making it a prime candidate for probing atmospheric escape
from HD 60779 b. HD 60779 is also the third-brightest host of a sub-Neptune
with orbital period greater than 25 days and with both mass and radius
measured, distinguishing it in terms of accessibility to spectroscopic
characterization.
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