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Accueil > Séminaires > Archive des séminaires d’Utinam > 2013

Arvind Singh Rajpurohit

Physical Parameters of Low-Mass stars (M-dwarfs) using high and low-resolution spectroscopy

vendredi 30 août 2013, 10h30

salle de conférences de l’observatoire

Arvind Singh Rajpurohit, Doctorant à l’Institut UTINAM, Observatoire des Sciences de l’Univers THETA de Franche-Comté Bourgogne

Résumé :

Very Low-Mass stars (M dwarfs) are an important source of information for probing the low mass end of the main sequence, down to the hydrogen burning limit. They are the dominant stellar component of the Galaxy and make up the majority of baryonic matter in the Galaxy. Moreover, an increasing number of M dwarfs are now known to host exoplanets, including super-Earth exoplanets. The determination of accurate fundamental parameters for M dwarfs has therefore relevant implications for both stellar and Galactic astronomy as well as planetology. Despite their large number in the Galaxy, M dwarfs remain elusive objects and the modelling of their photosphere has long remained a challenge (molecular opacities, dust cloud formation). The description of these stars therefore need a strong empirical basis, or validation. In particular, the effect of metallicity on the physics of cool atmospheres are still poorly known, even for early-type M-dwarfs. The goal of this work is to determine the fundament stellar parameter of these low-mass dwarfs (M dwarfs and M subdwarfs) using high and low resolution spectroscopy and to test recent model atmospheres. In particular this works aims to validate the BT-Settl model atmospheres, to understand the onset of dust formation in cool stellar atmospheres.