In:
Astronomy & Astrophysics, EDP Sciences, Vol. 623 ( 2019-3), p. A165-
Abstract:
We report on the confirmation and mass determination of a transiting planet orbiting the old and inactive G7 dwarf star HD 219666 ( M ⋆ = 0.92 ± 0.03 M ⊙ , R ⋆ = 1.03 ± 0.03 R ⊙ , τ ⋆ = 10 ± 2 Gyr). With a mass of M b = 16.6 ± 1.3 M ⊕ , a radius of R b = 4.71 ± 0.17 R ⊕ , and an orbital period of P orb ≃ 6 days, HD 219666 b is a new member of a rare class of exoplanets: the hot-Neptunes. The Transiting Exoplanet Survey Satellite (TESS) observed HD 219666 (also known as TOI-118) in its Sector 1 and the light curve shows four transit-like events, equally spaced in time. We confirmed the planetary nature of the candidate by gathering precise radial-velocity measurements with the High Accuracy Radial velocity Planet Searcher (HARPS) at ESO 3.6 m. We used the co-added HARPS spectrum to derive the host star fundamental parameters ( T eff = 5527 ± 65 K, log g ⋆ = 4.40 ± 0.11 (cgs), [Fe/H]= 0.04 ± 0.04 dex, log R ′ HK = −5.07 ± 0.03), as well as the abundances of many volatile and refractory elements. The host star brightness (V = 9.9) makes it suitable for further characterisation by means of in-transit spectroscopy. The determination of the planet orbital obliquity, along with the atmosphericmetal-to-hydrogen content and thermal structure could provide us with important clues on the formation mechanisms of this class of objects.
Type of Medium:
Online Resource
ISSN:
0004-6361
,
1432-0746
DOI:
10.1051/0004-6361/201834853
Language:
English
Publisher:
EDP Sciences
Publication Date:
2019
detail.hit.zdb_id:
1458466-9
SSG:
16,12
