Sophie Rosu
Dr Sophie Rosu
Post-doc
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+41 22 379 22 01
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Bio
Originally born and raised in Belgium, I studied both Astrophysics and Aerospace Engineers in the AV短视频 of Li猫ge. I did my PhD in the same institute working on the apsidal motion in massive eccentric binaries as a means to sound the stellar interiors, and earned my title in Summer 2022. In October of that year, I joined the KTH Royal Institute of Technology in Stockholm, Sweden to work on the latest observations of Supernova 1987A. In October 2024 I joined the Stellar Evolution team in Geneva Observatory to get back to the study of apsidal motion in massive binaries.
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Research Works
Apsidal motion as a means to sound the interiors of stars
In the last decades, it became evident that the majority of massive stars are bound by gravitational attraction to a companion forming a so-called binary star.听That massive stars predominantly evolve in binaries is a tremendous opportunity to better constrain their internal structure. A close eccentric binary sees its orbit slowly precessing in time as a consequence of the tidal interactions occurring between the two stars. This secular precession of the binary orbit鈥檚 major axis is called the apsidal motion, which rate is directly related to the internal structure constant of each star, a measure of the mass distribution between the core and the external layers of the star.听Measuring the apsidal motion rate hence provides a diagnostic of the otherwise difficult to constrain internal structure of stars and offers a test of our understanding of stellar structure and evolution.
My work as an observer consists in deriving the apsidal motion rate of massive eccentric binaries using both their spectroscopic and photometric data. In the meantime, I consistently derive all stellar (mass, radius, effective temperature, luminosity) and orbital (orbital period, eccentricity, semi-major axis, time of periastron passage, argument of periastron) parameters of the binaries.
My work as a theoretician consists in building dedicated stellar evolution models to reproduce all observational parameters of the binaries, including the apsidal motion rate and its link to the internal stellar structure constants. Simple? In theory... yes. In practise, I discovered that the standard stellar evolution models are unable to reproduce the density profile of the stars, that is to say, they produce stars that have a too low density contrast between the core and the external layers. The only way to reproduce the apsidal motion of the system together with the stellar parameters is to introduce a significant amount of internal mixing inside the stellar models. But what is the physical meaning behind this enhanced mixing? Stay tuned... that's exactly what I want to discover with GENEC!
Interested in learning more? Then visit this interactive e-Poster I presented during the EAS annual meeting 2024:
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Latests news from Supernova 1987A听
Supernova 1987A, in the Large Magellanic Cloud, the first naked eye supernova since the Kepler one in 1604, is the most famous supernova, but also the most observed and studied object in the sky after our Sun. SN 1987A has been monitored by the Hubble Space Telescope since the launch of the satellite, and I have recently worked on multi-wavelength HST imaging to understand its morphology and both its spectral and temporal evolution. If you are interested in learning more about this spectacular supernova, watch out my recent publication!听
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Publications
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