FLORES TRIVIGNO Matias Gaston
Are Am stars and hot-Jupiter planets related?
CARLOS SAFFE; J. ALACORIA; PAULA MIQUELARENA; PETRUCCI, R; JAQUE ARANCIBIA, M; RODOLFO ANGELONI; MARTIOLI, E.; FLORES MATÍAS; JOFRÉ, E; COLLADO, ANA; GUNELLA, FERNANDO
ASTRONOMY AND ASTROPHYSICS
EDP SCIENCES S A
Lugar: Paris; Año: 2022
Context. Metallic-lined Am stars are often components of short-period binary systems, where tidal interactions would result in low rotational velocities and help to develop the chemical peculiarities observed. However, the origin of single Am stars and Am stars that belong to wide binary systems is unclear.Aims. There is very recent evidence of an Am star hosting a hot-brown dwarf likely synchronized and other possible Am stars hosting hot-Jupiter planets. Following literature suggestions, we wonder if these hot-low mass companions could play a role in the development of an Am star, that is to say, if they could help to mitigate the "single Am" problem.Methods. We carried out a detailed abundance determination via spectral synthesis of 19 early-type stars hosting hot-brown dwarfs and hot-Jupiter planets, in order to determine the possible presence of Am stars in this sample. The abundances were determined iteratively for 25 different species by fitting synthetic spectra using the SYNTHE program together with local thermodynamic equilibrium (LTE) ATLAS12 model atmospheres. The abundances of Ci, O i and Mg i were corrected by non-LTE effects. The complete chemical patterns of the stars were then compared to those of Am stars and other chemically peculiar stars.Results. We studied a sample of 19 early-type stars, 7 of them hosting hot-brown dwarfs and 12 of them hosting hot-Jupiter planets. We detected 4 Am stars in our sample (KELT-19A, KELT-17, HATS-70 and TOI-503) and 2 possible Am stars (TOI-681 and HAT-P-69). In particular, we detected the new Am star HATS-70 which hosts a hot-brown dwarf, and rule out this class for the hot-Jupiter host WASP-189, both showing different composition than previously reported. For the first time, we estimated the incidence of Am stars within stars hosting hot-brown dwarfs (50-75%) and within stars hosting hot-Jupiters (20-42%). In particular, the incidence of Am stars hosting hot-brown dwarfs resulted higher than the frequency of Am stars in general. This would imply that the presence of hot-brown dwarfs could play a role in the development of Am stars and possibly help to mitigate the "single Am" problem, differentto the case of hot-Jupiter planets. Notably, these results would also indicate that the search for hot-brown dwarfs may be benefited by targeting single Am stars or Am stars in wide binary systems. We encourage the analysis off additional early-type stars hosting hot-companions in order to improve the significance of the initial trends found here.