Fringe tracking for multi chromatic imaging – advanced performance for the Interferometric Survey of Stellar Parameters

The Interferometric Survey of Stellar Parameters 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 as faint as magnitude 8 in the visible and as small as 0.2 milliseconds of arc. It benefits from 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. The ISSP team is opening this postdoc position to support the scientific programs of the survey through a dedicated effort on the fringe tracking facility and image reconstruction.

This position is focused on the imaging part of the survey, mainly related to the subprograms S05 (limb darkening), S06 (binary), S07 (fast rotators) and S08 (disks and winds). The goal is to open the possibility of image reconstruction combining R-band data (SPICA-VIS), H-band data (MIRCx) and K-band data (MYSTIC), using the three instruments simultaneously with the 15 baselines of CHARA. To achieve the required performance for the different programs, we need to have a fully operational fringe tracker, called SPICA-FT, and that can be operated routinely every night.

Part of the activity will be dedicated to the optimization of the fringe tracking capabilities and to its consolidation as a routine service tool for interferometric observations. This supposes some works to correctly parametrize the system for the different kinds of objects (bright/faint, unresolved/resolved) and to characterize the stability of the fringe phase over the large domain of wavelengths, from 0.7µm to 2.4µm. This also includes a potential amelioration of the operation of the longitudinal dispersion compensators.

The characterization of the progresses will be guided by the imaging program of the survey, mainly for complex objects for which the measurement of the angular diameter is not enough for the science objectives.

Experience in interferometric instrumentation is necessary.

We welcome applicants with diverse backgrounds and experiences. We regard gender equality and diversity as a strength and an asset.