Evolved stars and the origin of abundance trends in planet hosts
Entidad
UAM. Departamento de Física TeóricaEditor
EDP SciencesFecha de edición
2016-04-01Cita
10.1051/0004-6361/201527883
Astronomy & Astrophysics 588 (2016): A98 reproduced with permission from Astronomy & Astrophysics
ISSN
0004-6361 (print); 1432-0746 (online)DOI
10.1051/0004-6361/201527883Financiado por
This research was supported by the Italian Ministry of Education, University, and Research through the “PREMIALE WOW 2013” research project under grant “Ricerca di pianeti intorno a stelle di piccola massa”. E.V. acknowledges support from the “On the rocks” project funded by the Spanish Ministerio de Economía y Competitividad under grant AYA2014- 55840-PProyecto
Gobierno de España. AYA2014- 55840-PVersión del editor
10.1051/0004-6361/201527883Materias
Planetary systems; Stars: abundances; Stars: late-type; Techniques: spectroscopic; FísicaNota
Astronomy & Astrophysics 588 (2016): A98 reproduced with permission from Astronomy & AstrophysicsDerechos
© 2016 ESOResumen
Detailed chemical abundance studies have revealed different trends between samples of planet and non-planet hosts. Whether these trends are related to the presence of planets or not is strongly debated. At the same time, tentative evidence that the properties of evolved stars with planets may be different from what we know for main-sequence hosts has recently been reported. Aims. We aim to test whether evolved stars with planets show any chemical peculiarity that could be related to the planet formation process. Methods. In a consistent way, we determine the metallicity and individual abundances of a large sample of evolved (subgiants and red giants) and main-sequence stars that are with and without known planetary companions, and discuss their metallicity distribution and trends. Our methodology is based on the analysis of high-resolution echelle spectra (R ≳ 57 000) from 2-3 m class telescopes. It includes the calculation of the fundamental stellar parameters, as well as individual abundances of C, O, Na, Mg, Al, Si, S, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, and Zn. Results. No differences in the XFe vs. condensation temperature (TC) slopes are found between the samples of planet and non-planet hosts when all elements are considered. However, if the analysis is restricted to only refractory elements, differences in the TC-slopes between stars with and without known planets are found. This result is found to be dependent on the stellar evolutionary stage, as it holds for main-sequence and subgiant stars, while there seems to be no difference between planet and non-planet hosts among the sample of giants. A search for correlations between the TC-slope and the stellar properties reveals significant correlations with the stellar mass and the stellar age. The data also suggest that differences in terms of mass and age between main-sequence planet and non-planet hosts may be present. Conclusions. Our results are well explained by radial mixing in the Galaxy. The sample of giants contains stars that are more massive and younger than their main-sequence counterparts. This leads to a sample of stars that are possibly less contaminated by stars that were not born in the solar neighbourhood, leading to no chemical differences between planet and non-planet hosts. The sample of main-sequence stars may contain more stars from the outer disc (specially the non-planet host sample) which might lead to the differences observed in the chemical trends
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Google Scholar:Maldonado, J.
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Villaver Sobrino, Eva Gloria
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