English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

With the construction of the VLTI (Very Large Telescope Interferometer of theEuropean Observatory ESO for the southern hemisphere) it is now possible tomake observations with resolutions of the order of milli-arc-seconds,especially in IR with AMBER instrument (Astronomical Multi Beam Recombine).These new capabilities allow us to better constrain the stellar structures suchas polar jets, equatorial disks and flattened photospheres of rotating stars.Thus the estimation of stellar fundamental parameters allows to explore indetail the mechanisms of mass loss, pulsation and magnetism governing thevariability and the evolution of the stars.  This thesis presents the results of fast rotating stars observations carriedout on the AMBER spectro-interferometer VLTI in its high \& medium spectralresolutions modes. The observations were highly degraded by the optical defectsof AMBER and their analysis required the development of specific digitalreduction tools to reach the necessary precision for the interferometricmeasurements interpretation. In order to interpret those measures I developed achromatic semi-analytical model of rapidly rotating star that allowed me toestimate, from the differential phases; the degree of flattening, theequatorial radius, the rotation velocity, the angle of inclination, theposition angle of the star rotation axis in the sky, the local distribution ofthe effective temperature and the surface gravity of the star within the vonZeipel theorem. The results for four massive stars of spectral types B, A and Fhave allowed me to characterize the mechanisms discussed above and thus opensome prospect for more systematic studies of similar objects, with extendinglater these studies to the relationship photosphere - circumstellar envelope.

Observations et mod\'elisations spectro-interf\'erom\'etriques longue base des \'etoiles et de leur environnement proche