A hot mini-Neptune in the radius valley orbiting solar analogue HD 110113. Issue 4 (25th January 2021)

• Record Type: Journal Article
• Authors: Osborn, H P; Armstrong, D J; Adibekyan, V; Collins, K A; Delgado-Mena, E; Howell, S B; Hellier, C; King, G W; Lillo-Box, J; Nielsen, L D; Otegi, J F; Santos, N C; Ziegler, C; Anderson, D R; Briceño, C; Burke, C; Bayliss, D; Barrado, D; Bryant, E M; Brown, D J A; Barros, S C C; Bouchy, F; Caldwell, D A; Conti, D M; Díaz, R F; Dragomir, D; Deleuil, M; Demangeon, O D S; Dorn, C; Daylan, T; Figueira, P; Helled, R; Hoyer, S; Jenkins, J M; Jensen, E L N; Latham, D W; Law, N; Louie, D R; Mann, A W; Osborn, A; Pollacco, D L; Rodriguez, D R; Rackham, B V; Ricker, G; Scott, N J; Sousa, S G; Seager, S; Stassun, K G; Smith, J C; Strøm, P; Udry, S; Villaseñor, J; Vanderspek, R; West, R; Wheatley, P J; Winn, J N;
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 502:Issue 4(2021)
• Page Start: 4842
• Page End: 4857
• Publication Date: 2021-01-25
• Subjects: planets and satellites: detection -- stars: individual: HD110113; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stab182
• Languages: English
• ISSNs: 0035-8711

Abstract

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 ( T eff = 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.