Ecole Doctorale Sciences Fondamentales et Appliquées
Université Nice Sophia Antipolis
UFR Sciences
de déconvolution, et des codes de transfert radiatif dans le gaz et/ou la poussière.
Description of the thesis
Massive stars play a non-negligible role in galactic evolution, stellar formation, and
enrichment of interstellar medium with heavy elements, radiative and kinetic energy. As a
natural tracer of mass transfer between the star and the interstellar medium, the study of
the circumstellar environment is crucial to progress in the understanding of massive stars
evolution (Maeder & Meynet 2003) and stellar populations (Décressin et al. 2007).
Fast-rotation and binarity are the main phenomena responsible for the break of symmetry
of the mass-loss that can impact stellar evolution. These phenomena, common among
massive stars, are believed to be the cause of the formation of disks around some class of
stars, especially classical Be stars (fast-rotator with gaseous disks) and B[e] stars
(supergiant with non-spherical gaseous and dusty environments).
To constrain mass-loss, one must characterize the geometry and dynamics of the
circumstellar medium. Depending on their extension, this can be done using direct
imaging (with high-performance adaptive optics) or using optical/IR long baseline
interferometry. The combination of these techniques allows to link the close-by and
further environments (Chesneau et al. 2005).
The Lagrange laboratory was heavily involved in the development and scientific
exploitation of VLTI first generation instruments AMBER and MIDI (see for example,
Domiciano de Souza et al. 2007, 2011; Borges Fernandes et al. 2009; Meilland 2007, 2010;
Millour 2009, 2011). These instruments proved the power of interferometry to probe
circumstellar environments and bring new insights to the understanding of massive stars
formation and evolution (Georgy et al. 2011; Meilland et al. 2012).
The Lagrange laboratory is now involved in the development of the MIDI successor,
MATISSE, which will be installed on the VLTI in 2017, and whose polychromatic imaging
capabilities in the mid-infrared will be unmatched. Lagrange is also involved in the
exploitation of the new direct imager VLT/SPHERE.
This PhD subject is centered on the study of massive stars environments with the new
VLTI (MATISSE, and also GRAVITY) and VLT (mainly SPHERE) instruments, especially
using the MATISSE guarantied time (GTO) of OCA on classical Be stars and B[e]
supergiants. It is also linked with the multi-bands spectro-interferometric studies of
massive stars initiated at the Lagrange laboratory.
The PhD student will work in the stellar physics group of the laboratory and will
participate to MATISSE commissioning, observations, and data modelling. He will also
work on SPHERE programs on the break of symmetry of massive star winds.
The data modelling and astrophysical interpretation will be done using various tools
developed or used in the Lagrange laboratory: geometric and kinematic toy models, image
reconstruction and deconvolution software, and radiative transfer codes in the gas and
dust.
Informations complémentaires
L'étudiant pourra participer à des observations à l'ESO-VLT(I) au Chili, avec des
instruments à la pointe de l'Astronomie mondiale.
The student can participate to the observations at the ESO-VLT(I) in Chile, with