event
Thursday 18 Mar 2010: Stellar Optical Interferometry: Fundamental Parameters & Stellar Surface Images
Dr Gerard van Belle - ESO, Garching, Germany
Physics, 4th Floor interaction area 15:30-16:30
Optical interferometry is providing new views on the universe to astronomers at the sub-milliarcsecond level, one to three orders of magnitude below even the best adaptive optics telescopes. In particular, observations with interferometers provide direct, independent constraint upon fundamental parameters such as temperature and radius for objects that are modelled poorly. Recent advances in beam combiner technology and interferometer infrastructure now also permit the stellar images to be constructed from interferometric data, which is useful for non-point-symmetric & time-variable photospheres. An example of each of these will be presented: for fundamental parameters, radius measurements of low-mass M-dwarfs that explore the onset of full atmospheric convection illustrate the technique's ability to probe the limits of the current generation of atmospheric models. For stellar imaging, observations of oblate photospheres of rapidly rotating A-type dwarfs directly reveal phenomena such as gravity darkening and limb darkening; again, the competition between radiative and convective transfer generates fascinating atmospheric characteristics directly seen by interferometry.
