A hot mini-Neptune in the radius valley orbiting solar analogue HD 110113
Abstract
We report the discovery of HD 110113 b (TESS object of interest-755.01), a transiting mini-Neptune exoplanet on a 2.5-d orbit around the solar-analogue HD 110113 (Teff = 5730 K). Using TESS photometry and High Accuracy Radial velocity Planet Searcher (HARPS) radial velocities gathered by the NCORES program, we find that HD 110113 b has a radius of 2.05 ± 0.12 R⊕ and a mass of 4.55 ± 0.62 M⊕. The resulting density of $2.90^{+0.75}_{-0.59}$ g cm-3 is significantly lower than would be expected from a pure-rock world; therefore HD 110113 b must be a mini-Neptune with a significant volatile atmosphere. The high incident flux places it within the so-called radius valley; however, HD 110113 b was able to hold on to a substantial (0.1-1 per cent) H-He atmosphere over its ~4 Gyr lifetime. Through a novel simultaneous Gaussian process fit to multiple activity indicators, we were also able to fit for the strong stellar rotation signal with period 20.8 ± 1.2 d from the RVs and confirm an additional non-transiting planet, HD 110113 c, which has a mass of 10.5 ± 1.2 M⊕ and a period of $6.744^{+0.008}_{-0.009}$ d.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- April 2021
- DOI:
- 10.1093/mnras/stab182
- arXiv:
- arXiv:2101.04745
- Bibcode:
- 2021MNRAS.502.4842O
- Keywords:
-
- planets and satellites: detection;
- stars: individual: HD110113;
- Astrophysics - Earth and Planetary Astrophysics
- E-Print:
- 17 pages, 11 figures. Accepted for publication at MNRAS. HARPS RVs available at https://dace.unige.ch/radialVelocities/?pattern=HD110113