Hot planets around cool stars – two short-period mini-Neptunes transiting the late K-dwarf TOI-1260. Issue 4 (22nd May 2021)

• Record Type: Journal Article
• Authors: Georgieva, I Y; Persson, C M; Barragán, O; Nowak, G; Fridlund, M; Locci, D; Palle, E; Luque, R; Carleo, I; Gandolfi, D; Kane, S R; Korth, J; Stassun, K G; Livingston, J; Matthews, E C; Collins, K A; Howell, S B; Serrano, L M; Albrecht, S; Bieryla, A; Brasseur, C E; Ciardi, D; Cochran, W D; Colon, K D; Crossfield, I J M; Csizmadia, Sz; Deeg, H J; Esposito, M; Furlan, E; Gan, T; Goffo, E; Gonzales, E; Grziwa, S; Guenther, E W; Guerra, P; Hirano, T; Jenkins, J M; Jensen, E L N; Kabáth, P; Knudstrup, E; Lam, K W F; Latham, D W; Levine, A M; Matson, R A; McDermott, S; Osborne, H L M; Paegert, M; Quinn, S N; Redfield, S; Ricker, G R; Schlieder, J E; Scott, N J; Seager, S; Smith, A M S; Tenenbaum, P; Twicken, J D; Vanderspek, R; Van Eylen, V; Winn, J N;
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 505:Issue 4(2021)
• Page Start: 4684
• Page End: 4701
• Publication Date: 2021-05-22
• Subjects: techniques: photometric -- techniques: radial velocities -- planets and satellites: atmospheres -- planets and satellites: individual: TOI-1260b, c -- planets and satellites: composition -- stars: low-mass -- planetary systems; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stab1464
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We present the discovery and characterization of two sub-Neptunes in close orbits, as well as a tentative outer planet of a similar size, orbiting TOI-1260 – a low metallicity K6 V dwarf star. Photometry from Transiting Exoplanet Survey Satellite ( TESS ) yields radii of R b = 2.33 ± 0.10 and R c = 2.82 ± 0.15 R⊕, and periods of 3.13 and 7.49 d for TOI-1260 b and TOI-1260 c, respectively. We combined the TESS data with a series of ground-based follow-up observations to characterize the planetary system. From HARPS-N high-precision radial velocities we obtain M b = $8.6 _{ - 1.5 } ^ { + 1.4 }$ and M c = $11.8 _{ - 3.2 } ^ { + 3.4 }$ M⊕ . The star is moderately active with a complex activity pattern, which necessitated the use of Gaussian process regression for both the light-curve detrending and the radial velocity modelling, in the latter case guided by suitable activity indicators. We successfully disentangle the stellar-induced signal from the planetary signals, underlining the importance and usefulness of the Gaussian process approach. We test the system's stability against atmospheric photoevaporation and find that the TOI-1260 planets are classic examples of the structure and composition ambiguity typical for the 2–3 R⊕ range.