Format:
41
ISSN:
1432-0746
Content:
〈i〉Context〈b〉.〈b/〉〈i/〉 The Gl 486 system consists of a very nearby, relatively bright, weakly active M3.5 V star at just 8 pc with a warm transiting rocky planet of about 1.3 〈i〉R〈i/〉〈sub〉⊕〈sub/〉 and 3.0 〈i〉M〈i/〉〈sub〉⊕〈sub/〉. It is ideal for both transmission and emission spectroscopy and for testing interior models of telluric planets.〈i〉Aims〈b〉.〈b/〉〈i/〉 To prepare for future studies, we aim to thoroughly characterise the planetary system with new accurate and precise data collected with state-of-the-art photometers from space and spectrometers and interferometers from the ground.〈i〉Methods〈b〉.〈b/〉〈i/〉 We collected light curves of seven new transits observed with the CHEOPS space mission and new radial velocities obtained with MAROON-X at the 8.1 m Gemini North telescope and CARMENES at the 3.5 m Calar Alto telescope, together with previously published spectroscopic and photometric data from the two spectrographs and TESS. We also performed near-infrared interferometric observations with the CHARA Array and new photometric monitoring with a suite of smaller telescopes (AstroLAB, LCOGT, OSN, TJO). This extraordinary and rich data set was the input for our comprehensive analysis.〈i〉Results〈b〉.〈b/〉〈i/〉 From interferometry, we measure a limb-darkened disc angular size of the star Gl 486 at 〈i〉θ〈i/〉〈sub〉LDD〈sub/〉 = 0.390 ± 0.018 mas. Together with a corrected 〈i〉Gaia〈i/〉 EDR3 parallax, we obtain a stellar radius 〈i〉R〈i/〉〈sub〉〈i〉*〈i/〉〈sub/〉 = 0.339 ± 0.015 〈i〉R〈i/〉〈sub〉⊕〈sub/〉. We also measure a stellar rotation period at 〈i〉P〈i/〉〈sub〉rot〈sub/〉 = 49.9 ± 5.5 days, an upper limit to its XUV (5-920 A) flux informed by new 〈i〉Hubble〈i/〉/STIS data, and, for the first time, a variety of element abundances (Fe, Mg, Si, V, Sr, Zr, Rb) and C/O ratio. Moreover, we imposed restrictive constraints on the presence of additional components, either stellar or sub-stellar, in the system. With the input stellar parameters and the radial-velocity and transit data, we determine the radius and mass of the planet Gl 486 b at 〈i〉R〈i/〉〈sub〉p〈sub/〉 = 1.343〈sub〉−0.062〈sub/〉〈sup〉+0.063〈sup/〉 〈i〉R〈i/〉〈sub〉⊕〈sub/〉 and 〈i〉M〈i/〉〈sub〉p〈sub/〉 = 3.00〈sub〉−0.12〈sub/〉〈sup〉+0.13〈sup/〉 M〈sub〉⊕〈sub/〉, with relative uncertainties of the planet radius and mass of 4.7% and 4.2%, respectively. From the planet parameters and the stellar element abundances, we infer the most probable models of planet internal structure and composition, which are consistent with a relatively small metallic core with respect to the Earth, a deep silicate mantle, and a thin volatile upper layer. With all these ingredients, we outline prospects for Gl 486 b atmospheric studies, especially with forthcoming 〈i〉James Webb〈i/〉 Space Telescope (〈i〉Webb〈i/〉) observations.
Note:
Gesehen am 17.11.2022
In:
Astronomy and astrophysics, Les Ulis : EDP Sciences, 1969, 665(2022), Artikel-ID A120, Seite 1-41, 1432-0746
In:
volume:665
In:
year:2022
In:
elocationid:A120
In:
pages:1-41
In:
extent:41
Language:
English
DOI:
10.1051/0004-6361/202243548
URL:
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