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Spectroscopy of pulsations in γ Doradus Stars

Spectroscopy of pulsations in γ Doradus Stars. Emily Brunsden Department of Physics and Astronomy University of Canterbury emily.brunsden@pg.canterbury.ac.nz. Image: http://gong.nso.edu/.  Doradus Stars. Pulsating late A to early F stars On or near main sequence

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Spectroscopy of pulsations in γ Doradus Stars

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  1. Spectroscopy of pulsations in γ Doradus Stars Emily Brunsden Department of Physics and Astronomy University of Canterbury emily.brunsden@pg.canterbury.ac.nz Image: http://gong.nso.edu/

  2.  Doradus Stars • Pulsating late A to early F stars • On or near main sequence • Periods of 0.3 - 3 days • More than 60 confirmed • Have non-radial g-mode pulsations Image: J. Christensen-Dalgaard

  3. Motivation for a thesis • g-modes travel deep in star and inform stellar models- but few have been studied • Are current mode identification techniques optimal? • Does the rotation of the star create observable pulsation effects? Image: http://www.hao.ucar.edu/

  4. The Study of HD135825 • 300 spectra over 18 months • Not well-studied star • Low projected rotational velocity

  5. Representative Line Profile

  6. Power Multi-Periodic Variations 1.31 cycles day-1 0.29 cycles day-1 0.42 cycles day-1 1.88 cycles day-1 Frequency

  7. line profile Power Modelling all Modes standard deviation 1.31 cycles day-1 0.29 cycles day-1 0.42 cycles day-1 1.88 cycles day-1 velocity (km/s)

  8. standard deviation Modelling all Modes 1.31 cycles day-1 0.29 cycles day-1 Amplitude Amplitude 1.88 cycles day-1 velocity (km/s) Wavelength (velocity space) kms-1 Amplitude Amplitude Wavelength (velocity space) kms-1 Wavelength (velocity space) kms-1 Wavelength (velocity space) kms-1

  9. Results for HD 135825 Image: http://www.physics.usyd.edu.au/~bedding/animations/visual.html

  10. γ Doradus • Class definition- well studied • 620 spectra over 15 months • Four frequencies found, agree very well • Modes consistent with other studies

  11. HD12901 • Clear pulsations from classification study • 470 spectra over 31 months at MJUO plus 110 from Chile and USA • Six frequencies – 2 new • Five modes- all (1,1)

  12. HD49434 • Hybrid γ Doradus/ δ Scuti Star • CoRoT satellite frequencies (more than 800) • 660 spectra over five years at MJUO plus 1080 from France, Chile and Spain • 31 frequencies -almost none seen in photometry • Two distinct classes of frequency (0.2-2 d-1 and >3 d-1)

  13. HD49434 standard deviation δ Scuti-like γ Doradus-like velocity (km/s)

  14. Major Progress • Three stars with full mode identifications (previously only ~10) • Cross-correlation techniques are good for slow-moderate (vsini < 70 km/s ) rotators • (1,1) modes are common • Rotation can distort standard deviation profiles

  15. Future Challenges • Linking observed pulsations to theoretical models • Moving from observed to co-rotating frame • Hybrid stars & binaries

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