1 / 24

Pulsations in Wolf-Rayet stars :

This work explores pulsations in Wolf-Rayet (WR) stars using observations from the MOST satellite. WR stars, characterized by their hot, dense winds and high luminosity-to-mass ratios, are crucial to understanding stellar evolution and the ecology of the universe. We analyze pulsation periods and their impact on wind behavior, focusing on the peculiar WN8 stars WR 124 and WR 110. Our findings reveal photometric variability linked to core pulsations, highlighting the importance of studying these massive stars to address astronomical phenomena and the momentum problem.

selina
Télécharger la présentation

Pulsations in Wolf-Rayet stars :

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Pulsations in Wolf-Rayet stars : Observations with MOST André-Nicolas Chené (NRC/HIA/CGO) Anthony F. J. Moffat (Université de Montréal)

  2. Wolf-Rayet stars • Hot and dense wind • WN and WC WN HeII NIII HeII HeII WC CIII CIV

  3. 25 to 40 M O RSG/LBV WN SN 40 to 75 M O LBV WN → WC SN more than 75 M O WNha → LBV → WN → WC SN Evolution of massive stars

  4. Why observe WR star? • WR = epitome of hot stars with strong, stable winds • significant contributors to the ecology of the Universe • look for pulsations to (help) drive the winds: Momentum problem: [dM/dt v] / [L/c] < 1 for O stars (~OK), up to 10+ for WR (OK?)

  5. Strange-Mode Pulsations • Glatzel 1993-99-08 • Stars with a high L/M, where radiation pressure domines. • The most violent SMPs are expected in Wolf-Rayet stars. • Opacity bump due to iron. • Periods of a few minutes or hours are expected (but, finally, maybe days…).

  6. Previous results with MOST Fourier spectrum Time series

  7. WR103 WR123 Previous results with MOST Lines ~ 10% of broadband flux & vary relatively little • obs’d photometric variability must be related to pulsations of the stellar core! • delayed reaction of wind (lines) triggered by superposition of pulsation events

  8. Previous results with MOST  Stochastic clumps have no effect on period detection (Moffat et al. 2008)

  9. WR 124 • WN8(h) • WN8 stars are peculiar: 1) single, 2) high proper motion, 3) far from galactic plane, 4) mostly isolated and 5) very variable

  10. Cleaning the Light Curve : WR 124

  11. Cleaning the Light Curve : WR 124 comp1 WR124 comp2

  12. Cleaning the Light Curve : WR 124 comp2

  13. Periodogram : WR 124

  14. 0.71 c/d 0.29 c/d Periodogram : WR 124 P = 1.41 d, 3.45 d

  15. Spectroscopy : WR 124 • EW, skewness & Kurtosis Binary?: K=5 km/s Mcomp<2M if i>10º (Moffat et al. 2010)

  16. Spectroscopy : WR 124 WR123 (WN8) WR124 (WN8h)

  17. 1% WR 110 • WN5-6 (single) • Light-curve (Chené et al. 2010)

  18. Spectroscopy : WR 110 Binary?: Mcomp<3M if i>20º (Chené et al. 2010)

  19. Spots? : WR 110 m f Lamontagne et al. (1996) m f

  20. Spots+CIRs? : WR 110 Cranmer & Owocki (1996)

  21. Spots+CIRs? : WR 110 WR6 HeII4686 Cranmer & Owocki (1996) Morel et al. (1997)

  22. Spots+CIRs? : WR 110 WR 1 (Chené & St-Louis 2010) WR 1 WR 134 (Morel et al. 1999) WR 110 WR 6 (Morel et al. 1997) WR 6 (Chené et al. 2010)

  23. Origin of CIRs Magnetic wind or Pulsations confinement • (R. Townsend, A. Ud-Doula)

  24. The END Thank you very much André-Nicolas Chené (NRC/HIA/CGO) Anthony F. J. Moffat (Université de Montréal)

More Related