Name/Affiliation: S. Shelyag (Monash University)
Modelling of spectro-polarimetric properties of stellar surfaces
Small-scale convective motions in the outer envelopes of low-mass stars induce variations and radial velocity shifts in stellar spectral line profiles. These variations, known as stellar jitter or astrophysical noise, are of the order of few meters per second. They make it difficult to confirm Earth-like exoplanets, which generate Doppler shifts of the order of centimeters per second. Understanding the physical processes involved in generation of astrophysical noise and its properties requires detailed modelling of the time-dependent photospheric thermal stratification, flows, oscillations and magnetic fields. In my presentation, I will describe a numerical technique for synthesis of spectro-polarimetric properties of full time-dependent stellar surfaces. The technique is based on radiative magneto-hydrodynamic modelling of magnetised photospheres with MURaM code and spectro-polarimetric diagnostics of the simulated photospheric models, which takes into account inclination of line-of-sight with respect to the normal to the stellar surface at different positions of stellar disk. The simulated models of stellar surfaces will be used in parameterisation of stellar jitter and in development of techniques of noise reduction in exoplanetary observations, which are more efficient than the current ones.