Asteroseismology and Magnetic Cycles
Ângela R. G. Santos
Small cyclic variations in the frequencies of acoustic modes are expected to be a common phenomenon in solar-like pulsators, as a result of stellar magnetic activity cycles. The frequency variations observed throughout the solar and stellar cycles contain information about structural changes that take place inside the stars as well as about variations in magnetic field structure and intensity. In the sun and solar-like pulsators, the direct effect of the magnetic field on the oscillations might be significantly important in regions of strong magnetic field (such as solar/stellar spots), where the Lorentz force can be comparable to the gas-pressure gradient. Our aim is to determine the sun-/starspot effect on the oscillation frequencies and attempt to understand if this effect contributes strongly to the frequency changes observed along the magnetic cycle. The total contribution of the spots to the frequency shifts results from a combination of direct and indirect effects of the magnetic field on the oscillations. I will present our results for the indirect effect associated with changes in the stratification within sunspots.
15 maio 2013, 13:30
Centro de Astrofísica
Rua das Estrelas