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Time Domain Astrophysics in South Africa 2. Astero-seismology. Astero-seismology. Monitoring Time variations in intrinsic variables in order to infer their properties such as mass, luminosity, rotation rate, internal composition. Seismic Waves trapped in Stars. Stars pulsate according to

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Presentation Transcript
astero seismology
Astero-seismology
  • Monitoring Time variations in intrinsic variables in order to infer their properties such as mass, luminosity, rotation rate, internal composition
seismic waves trapped in stars
Seismic Waves trapped in Stars
  • Stars pulsate according to

y=An( r ) Ylm (theta, phi) exp(-omega t)

Where n l m describe a mode

A good start to astero-seismology is in determining these for as many modes as possible

asteroseismology research in south africa
Asteroseismology Research in South Africa
  • Observational Studies include

- mode identification using photometry alone (determines l)

- mode identification using Baade-Wesselink methods (combination)

- mode-identification by observing line profile variations

On roAp stars, delta Scuti, sdB stars, beta Cepheid etc

search for new pulsating stars
Search for new Pulsating stars
  • Rapidly Oscillating Ap stars (SAAO)

5 min < Ppuls<16 min

frequency spectrum

like nothing you

have ever seen

dipole(-like)

new, improved

mode

strange doublet

Frequency Spectrum
pulsating sdb stars
Pulsating sdB stars
  • hot Horizontal Branch stars with temperatures of about 30,000 K
  • Periods 2 -3 minutes
observational facilities
Observational Facilities
  • Photo-electric photometers
  • CCDs (also have frame-transfer)
  • Giraffe spectrograph {R = 39000, wavelength 3820 - 9240 angstrom, V < 9}
  • SALT ?
theory
Theory
  • Non-linear theory (SAAO)
  • Radiative Transfer and Oscillations in A stars (UCT/SAAO)