Kolmogorov Unstable Stellar Oscillations

Stellar Oscillations Network Group

Stellar Oscillations Network Group (SONG) is an initiative aimed at designing and building a network of 1m-class telescopes dedicated to asteroseismology and planet hunting. SONG will have 8 identical telescope nodes each equipped with a high-resolution spectrograph and an iodine cell for obtaining precision radial velocities and a CCD camera for guiding and imaging purposes. The main asterosei...

Stochastic Excitation of Stellar Oscillations

Excitation of solar oscillations is attribued to turbulent motions in the solar convective zone. It is also currently believed that oscillations of low massive stars (M < 2 M⊙) which possess an upper convective zone are stochastically excited by turbulent convection in their outer layers. A recent theoretical work (Samadi and Goupil, 2001; Samadi et al., 2001) supplements and reinforces this th...

Lecture Notes on Stellar Oscillations

Discriminating stellar activity, oscillations and planets

Context. Bisectors of strong, single spectral lines, usually the Fe  6252 line, have traditionally been used to examine the velocity fields in stellar atmospheres. This requires high S/N often achieved by summing many individual spectra. Aims. We investigate whether bisectors derived from cross-correlation functions (CCF) of single-exposure spectra can be used to provide information on stellar...

Magnetic fingerprints of solar and stellar oscillations

Waves connect all the layers of the Sun, from its interior to the upper atmosphere. It is becoming clear now the important role of magnetic field on the wave propagation. Magnetic field modifies propagation speed of waves, thus affecting the conclusions of helioseismological studies. It can change the direction of the wave propagation, help channeling them straight up to the corona, extending t...