The HD 60779 Planetary System: A Transiting Sub-Neptune on a 30-day Orbit and a More Massive Outer World
Abstract
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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Cite
@article{arxiv.2508.16805,
title = {The HD 60779 Planetary System: A Transiting Sub-Neptune on a 30-day Orbit and a More Massive Outer World},
author = {Victoria DiTomasso and David Charbonneau and Andrew Vanderburg and Mercedes López-Morales and Shreyas Vissapragada and Annelies Mortier and Thomas G. Wilson and Elyse Incha and Andrew Collier Cameron and Luca Malavolta and Lars A. Buchhave and David W. Latham and Matteo Pinamonti and Stephanie Striegel and Michael Fausnaugh and Luke Bouma and Ben Falk and Robert Aloisi and Xavier Dumusque and A. Anna John and Ben S. Lakeland and A. F. Martínez Fiorenzano and Luca Naponiello and Belinda Nicholson and Emily K. Pass and Francesco Alfonso Pepe and Federica Rescigno and Alessandro Sozzetti and Daisy A. Turner and Saul A. Rappaport and Mark Omohundro and Brian P. Powell and Robert Gagliano and Thomas L. Jacobs and Veselin B. Kostov and Martti H. Kristiansen and Daryll M. LaCourse and Allan R. Schmitt and Hans Martin Schwengeler and Ivan A. Terentev},
journal= {arXiv preprint arXiv:2508.16805},
year = {2025}
}
Comments
18 pages, 12 figures, submitted to AAS Journals