|Thesis supervisor : ||
Université Paris Diderot et Institut Universitaire de France - LEPCHE/Laboratoire d'Etudes des Phénomènes Cosmiques de Haute Energie
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Massive stars live in pair...
A recent study shows that more than 70% of massive stars live in a stellar pair (Sana et al. 2012). This binarity has a major impact on the stellar evolution, strongly influenced by the presence of a "companion" star, especially via the transfer of material, angular momentum, and presence of intense stellar winds (Chaty 2013).
The fate of pairs of massive stars is determined by the evolution of each component, the most massive collapsing first in the supernova explosion, giving rise to a neutron star or a black hole (Tauris & van den Heuvel, 2006). This is the birth of a compact binary system -a compact object orbiting the companion star-, probably the most fascinating objects in the Universe. The compact object, immersed in the intense stellar wind of the massive companion star, attracts and accretes part of this wind, which accumulates on the surface, heated to temperatures of several million degrees, emitting mainly in X-rays. These celestial objects are subject to extreme variations in brightness, of several orders of magnitude on scaletime ranging from seconds to months.
... and influence their environment!
On one hand, it is now well established that the collapse of massive stars in supernova plays a key role in the enrichment of interstellar medium -from heavy atoms to complex molecules-, as well as in triggering the formation of new stars. On the other hand, the study of impact and feedback from massive stars on their environment throughout their life, has long been neglected, and remains largely unknown. However, all the material ejected through the stellar wind, and not intercepted by the compact object, is dispersed into the surrounding environment, thus colliding with a dense interstellar medium, potentially triggering new starbirth, as indicated by our recent observations with the Herschel satellite (Chaty et al. 2012 Coleiro et al. 2014).
This PhD thesis, covering many fields of Astrophysics, proposes to study the formation of pairs of massive stars, whose role is essential for the cycle of matter in galaxies, along with their evolution, and the impact on their environment, based on multi-wavelength observations.