Calibrating the MATISSE calibrators

Supervisor: Josef Hron

Contact information: josef.hron@univie.ac.at

Co-supervisors: Claudia Paladini (ESO, Chile)

Expected duration: 7 months

Project description & Goals:

MATISSE at the VLT Interferometer allows for the first time interferometry between 3 and 10 microns (L,M and N). Therefore it covers science cases like young stellar objects, evolved cool giants and supergiants, massive stars, planetary systems, and AGNs. The broad wavelength coverage poses a special challenge for calibration: calibrator stars observable in all three bands are often resolved in L, thus requiring accurate knowledge of their stellar atmosphere and predicted intensity profiles. This knowledge is rather limited for the cooler calibrators to the lack of previous observations. This is particularly relevant for cooler calobrators (K, M giants) which are needed for cool science targets.  Therefore a dedicated calibration program has been started at ESO to calibrate the likely resolved calibrators to unresolved ones.

The goals of this project are to compare the observations of cool calibrators with the predictions of state of the art model atmospheres for K and M stars and 

1) analyse how well the models can reproduce the observations and

2) improve the MATISSE calibration

Working plan & Milestones (including final thesis):

  • Month 1: familiarize with the MATISSE pipeline to reduce the calibrator observations
  • Month 2: select the calibrators to analyse, determine their stellar parameters, reduce the observations
  • Month 3-4: familiarize with available software and adopt it (or develop new one) for comparing the visibilities with predicted intensity profiles.
  • Month 5-6: compute the intensity profiles and compare with the observations
  • Month 7: writing of thesis

Requirements / special skills: knowledge about the basics of interferometry, IR-astronomy and stellar atmospheres

References:

Cruzalebes+  (2019): A catalogue of stellar diameters and fluxes for mid-infrared interferometry, Monthly Notices of the Royal Astronomical Society, Volume 490, Issue 3, p.3158-3176

Aringer+ (2016): Synthetic photometry for M and K giants and stellar evolution: hydrostatic dust-free model atmospheres and chemical abundances, Monthly Notices of the Royal Astronomical Society, Volume 457, Issue 4, p.3611-3628