Project Details
Abstract
Stellar seismology is concerned with the oscillations of stars and what they tell us about the structure and evolution of stars. Astronomical telescopes can only see the surface of the stars. The interior, in which the important
'cooking' of the chemical elements is taking place, is hidden from direct observation. Stellar oscillations allow us to probe and construct models of the interior. Fortunately, the majority of stars pulsate with a multitude of different oscillations - each of which contains information on the stellar envelope and interior. Only recently has the astronomical instrumentation become sensitive enough to be able to measure and correctly identify the many individual oscillations in a star.
The project will use space satellites and earth-based automatic and classical manual telescopes to measure the oscillations of selected so-called Delta Scuti and Gamma Doradus stars in the hydrogen-burning stage ('the stellar adulthood') and to use this information to compute theoretical stellar models of stars. In this project we emphasize the detection of a large number of pulsation frequencies with small amplitudes. Special attention will be given to pulsation mode identification: the identification of the individual oscillations with their physical nature (pressure or gravity modes; geometry given by the 'quantum numbers of oscillation'). To achieve this, brightness measurements and their variations need to be obtained in more than one wavelength region: we will use the Austrian automatic photoelectric telescope in Arizona, as well as the Austrian/Canadian MOST and BRITE satellites.
The stellar oscillations also lead to variations in the spectroscopic line profiles with different pulsation modes having specific signatures. The TOPS team was one of several pioneers in developing special techniques of analysis. Telescope measurements of the line profile variations as well as radial velocities will be obtained and combined with the simultaneous photometry.
The final step in our investigations is the theoretical modeling of the observed variations. Since the observed oscillations depend on the properties of the whole star, including the interior, we can derive tight constraints on the internal structure and tackle a number of complex problems such as convection and overshooting, effects of chemical composition, improved opacities, amplitude and period variability, stellar cycles, nonlinearities and hybrid pulsation.
'cooking' of the chemical elements is taking place, is hidden from direct observation. Stellar oscillations allow us to probe and construct models of the interior. Fortunately, the majority of stars pulsate with a multitude of different oscillations - each of which contains information on the stellar envelope and interior. Only recently has the astronomical instrumentation become sensitive enough to be able to measure and correctly identify the many individual oscillations in a star.
The project will use space satellites and earth-based automatic and classical manual telescopes to measure the oscillations of selected so-called Delta Scuti and Gamma Doradus stars in the hydrogen-burning stage ('the stellar adulthood') and to use this information to compute theoretical stellar models of stars. In this project we emphasize the detection of a large number of pulsation frequencies with small amplitudes. Special attention will be given to pulsation mode identification: the identification of the individual oscillations with their physical nature (pressure or gravity modes; geometry given by the 'quantum numbers of oscillation'). To achieve this, brightness measurements and their variations need to be obtained in more than one wavelength region: we will use the Austrian automatic photoelectric telescope in Arizona, as well as the Austrian/Canadian MOST and BRITE satellites.
The stellar oscillations also lead to variations in the spectroscopic line profiles with different pulsation modes having specific signatures. The TOPS team was one of several pioneers in developing special techniques of analysis. Telescope measurements of the line profile variations as well as radial velocities will be obtained and combined with the simultaneous photometry.
The final step in our investigations is the theoretical modeling of the observed variations. Since the observed oscillations depend on the properties of the whole star, including the interior, we can derive tight constraints on the internal structure and tackle a number of complex problems such as convection and overshooting, effects of chemical composition, improved opacities, amplitude and period variability, stellar cycles, nonlinearities and hybrid pulsation.
| Status | Finished |
|---|---|
| Effective start/end date | 1/10/09 → 30/09/13 |
Keywords
- Oscillations
- Asteroseismology
- Physical processes
- Stars
- Satellites
- Telescopes