Postdoc position "Surface brightness color relations and optical interferometry"

The Interferometric Survey of Stellar Parameters (ISSP) ERC-Adv grant, started on 1 Sep 2021 for 5 years, aims at realizing and exploiting an ambitious and homogenous survey of the angular diameters of a thousand stars. It takes benefit of the recently commissioned CHARA/SPICA instrument installed on the CHARA Array, Mount Wilson Observatory (USA, CA). The survey is built to address key questions about the relation between planets and stars and to offer to the broader community a unique and primary source of direct information on a representative and large sample of stars all over the HR diagram.

This position is focused on the S04 SPICA program aiming at collecting a few hundred of interferometric angular diameters over the HR diagram to build unique surface brightness color relations (SBCR). It is also related to additional programs of the survey aiming at understanding the bias in the determination of the stellar parameters in presence of various sources of variability. Constraining SBCR on different parts of the HR diagram is fundamental to determine the angular diameter of any non-active stars, even faint, for PLATO, but also for the distance determination of early-type eclipsing binaries in other galaxies, which is crucial for the calibration of the Hubble constant (in collaboration with the Araucaria Project). Contributing to the management of this observing program, in collaboration with the co-investigators of the ISSP survey, will be one of the main tasks of this position. Building SBCR is highly dependent on the quality of photometric data, but also on surface gravity and metallicity. Within the ISSP project we aim at obtaining, with the possible installation of a new infrared photometer at Calern Observatory, new high quality infrared photometry of the bright interferometric targets, together with spectroscopic diagnostics (from existing surveys or with additional time requests) for the sample of stars that will be used. The candidate will contribute to these additional observing programs, aiming at characterizing the variability of stars and its impact on the extraction of the fundamental parameters.