Found 4 talks width keyword stellar rotation
The new generation of spectrometers designed for extreme precision radial velocities enable correspondingly precise stellar spectroscopy. It is now fruitful to theoretically explore what the information content would be if stellar spectra could be studied with spectral resolutions of a million or more, and to deduce what signatures remain at lower resolutions. Hydrodynamic models of stellar photospheres predict how line profiles shapes, asymmetries, and convective wavelength shifts vary from disk center to limb. Corresponding high-resolution spectroscopy across spatially resolved stellar disks is now practical using differential observations during exoplanet transits, thus enabling the testing of such models. A most demanding task is to understand and to model spectral microvariability toward the radial-velocity detection of also low-mass planets in Earth-like orbits around solar-type stars. Observations of the Sun-as-a-star with extreme precision spectrometers now permit searches for spectral-line modulations on the level of a part in a thousand or less, feasible to test against hydrodynamic models of various solar features.
We will start by recalling the effects of rotation on stellar evolution and briefly explain its implementation in a stellar evolution code. We will present a set of various grids of massive stars models, and then show some recent results obtained by our new SYCLIST toolbox, which is able (among other things) to generate synthetic stellar clusters, including various physical ingredients, such as initial rotation and angle of view distributions, gravity and limb darkening, etc.
The application of the Fourier transform (FT) technique to high resolution spectra of OB-type stars has challenged our previous knowledge about stellar rotation in stars in the upper region of the HRD. The FT is an old and powerful tool that has being widely used in the case of cool stars, but only very recently applied to massive stars in a systematic way. In this talk I will present the results of the line-broadening characterization of ~250 Galactic OB-type stars (including dwarfs, giants and supergiants with spectral types O4-B9) from the IACOB spectroscopic database. I will show how these analyses have led to a downward revision of previously determined projected rotational velocities in these stars, and have definitely confirmed the presence of a non-negligible extra line-broadening contribution (commonly called macroturbulent broadening) in the whole OB star domain. I will also provide some notes about the importance of these findings on the evolution of massive stars and the detection of stellar oscillations along the lifetime of these important astrophysical objects.
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- IAU G5 -- The GALAH survey: science goals and highlights to dateSarah MartellTuesday January 25, 2022 - 10:30 GMT (Online)
- Dynamos, the drivers of solar and stellar activityProf. Axel BrandenburgThursday January 27, 2022 - 10:30 GMT (Online)