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New perspectives on B star X-ray emission: The high-resolution X-ray spectra of Spica and β Cen

New perspectives on B star X-ray emission: The high-resolution X-ray spectra of Spica and β Cen. Collaborators on both projects: Nathan Miller Joe Cassinelli β Cen Ton Raassen Emre Tepedelenlioglu Rolf Mewe Spica Ron Reynolds Joe MacFarlane Nate Hall.

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New perspectives on B star X-ray emission: The high-resolution X-ray spectra of Spica and β Cen

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  1. New perspectives on B star X-ray emission: The high-resolution X-ray spectra of Spica and β Cen

  2. Collaborators on both projects: • Nathan Miller • Joe Cassinelli • βCen • Ton Raassen • Emre Tepedelenlioglu • Rolf Mewe • Spica • Ron Reynolds • Joe MacFarlane • Nate Hall

  3. Main Question: Where and how do B stars produce their X-rays? Three approaches: • Line profiles – broadened or not? • Line ratios from He-like ions • Is X-ray flux affected by β Cep-type pulsations

  4. Stars’ Biographical Details

  5. β Cen XMM spectra

  6. Spica LETG-ACIS-S spectrum

  7. 1. Emission Line Profiles

  8. Profiles of CVI lineof β Cen

  9. Spica Line Profiles(vs. scaled Capella in red) (Capella Aa (the main X-ray source) had v ≈ +25 km/s during the observation shown here (Ishibashi & Dewey 2005)

  10. 2. f/i Ratios from He-like Ions

  11. f/i ratios for β Cen(Kurucz model)

  12. Spica’s Ne IX fir region

  13. Spica’s O VII fir region

  14. Density falloff in Spica’s windCritical Densities Marked:Radiation will control f/i ratio

  15. Interpreting Spica’s f/i ratios(Hubeny model)

  16. Interpreting Spica’s f/i ratios(Kurucz model – calc by MacFarlane)

  17. Spica’s H II region (Wisconsin H-Alpha Mapper (WHAM) image) -H II region is relatively isolated-Will use to measure ionizing flux and calibrate photospheric FUV/EUV flux which effects f/i ratios

  18. 3. X-ray Lightcurves

  19. β Cen Lightcurves: 3 XMM instruments

  20. β Cen – folded on β Cep period

  21. Spica β-Cep-Type History • Seen as β Cep variable by Shobbrook et al. (1969) with p=0.1738 d (pulsations evident in archived observations) • Photometric variations died out by 1972 (Lomb 1978) • May still be pulsing, but axis of NRP may have processed so that we are observing pole-on (Balona 1985) (precession period 130-140 yrs) (Dukes 1974)

  22. Spica’s X-ray Lightcurve

  23. Spica data folded on β Cep period

  24. Conclusions: • X-ray emission lines are not strongly Doppler-broadened in either case • He-like ions indicate X-rays formed at a range of radii (at least for Spica) • No evidence is found for either star to be variable in X-rays on their β Cep periods

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