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AMBER observations of Be Stars

AMBER observations of Be Stars. Anthony Meilland And Philippe Stee. Be Stars definition. Active hot Stars :. 8000K<Teff<40000k. Emission lines. Infrared Exces. Non Supergiant stars. Near main sequence. exclude Herbig Ae/Be (Young stars). exclude P Cygny (Supergiant stars).

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AMBER observations of Be Stars

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  1. AMBER observations of Be Stars Anthony Meilland And Philippe Stee

  2. Be Stars definition Active hot Stars : 8000K<Teff<40000k Emission lines Infrared Exces Non Supergiant stars Near main sequence exclude Herbig Ae/Be (Young stars) exclude P Cygny (Supergiant stars) No Forbidden lines exclude B[e] stars Include Be-shell (edge-on Be stars ) Be one day  Be forever

  3. Questions about Be stars Ejection of Matter from the central star Rapid Rotation Radiative stellar wind Non-radial pulsations Magnetism Reorganization of the matter around the star Expanding or rotating disk Disk open angle (Hydrostatic equilibrium, wind compressed disk) Polar wind strength Effect of magnetic fields Variability : origin and role Pulsations Overdensity rotation or precession (One-Armed Oscillation) Magnetic fields effect Continuous mass ejection or outbursts Equatorial disk formation and dissipation (Be  Be-Shell  B normal)

  4. Why using differential interferometry To study Be stars? Rot Exp

  5. Results and futures observations α Arae (MIDI + AMBER) Κ CMA (AMBER) Coming soon! New AMBER + MIDI AMBER δ Sco Achernar (VINCI) Coming not so soon But we hope not too late! New AMBER

  6. αAra Observed with MIDI 8-13.5μm Visibilities Short term Spectroscopic variations B=102 m , PA = 7° B=79 m , PA = 55° Companion at 32R*? unresolved Smaller than what we expected (<3mas for UD or <7mas US+UD) Disk truncation at 22R* ? Chesneau, Meilland et. Al A&A 2005

  7. αAra Observed with AMBER Envelope extension No significant envelope size variation Between 2 and 13μm Enveloppe ~40% total flux at 2μm Meilland et al. 2007 A&A

  8. αAra Observed with AMBER geometry Meilland et al. 2007 A&A

  9. αAra Observed with AMBER geometry Meilland et al. 2007 A&A

  10. αAra Observed with AMBER geometry Meilland et al. 2007 A&A

  11. αAra Observed with AMBER geometry Meilland et al. 2007 A&A

  12. αAra Observed with AMBER Kinematics : expansion or rotation (or both) VΦ >> Vr VΦ ~ Vr Meilland et al. 2007 A&A

  13. αAra Observed with AMBER Kinematics : expansion or rotation (or both) VΦ >> Vr VΦ ~ Vr Meilland et al. 2007 A&A

  14. αAra Observed with AMBER Keplerian rotation (β =0.48±0.05) Critical rotation Vrot~Vc Kinematics : expansion or rotation (or both) Meilland et al. 2007 A&A

  15. αAra Observed with AMBER ρequ ~10-100 ρpol Rdisk =32R* Vexp(eq)<10kms-1 Vexp(pol)~100-1000kms-1 Φequ <10 Φpol Best Simeca model Meilland et al. 2007 A&A

  16. Disk and Wind Κ CMA (AMBER) Achernar (VINCI) Meilland et al. 2007 A&A Kervella et Domiciano de Souza. 2006 A&A Equatorial disk : 50% of ftot at 2μm 5% total flux Rdisk = 23R* No equatorial disk (<5R*) No polar wind detected Poorly resolved

  17. Disk and wind Permanent Equatorial disk ( αArae and κ Cma ) Rdisk~20-30 R* (also spectroscopic clues of a non permanent disk around Achernar 8R*) Fdisk(K)~0.5Ftot Polar wind ( α Arae and Achernar) Ljet>10R* Fjet~1-5%F* different mechanisms produce the polar wind and the Equatorial disk ? Disk open angle? Wind open angle? And Between?

  18. KINEMATICS κCMa Achernar Meilland et al. 2007 A&A Domiciano de Souza et al. A&A Vinicius et al. 2005 A&A NO expansion (VΦ >> Vr ) Critical rotation Non keplerian rotation (β =0.3±0.1) No equatorial disk during VINCI obervations In 2002 Sub-critical rotation Vrot~0.52Vc Disk between 1991 and 1998? Inhomogeneity aligned with major-axe?

  19. NEXT? PSF (72 bases ATs) Image reconstruction with AMBER 4 Complete observation nights avec each of the 4 «triplets» available for P79 Accepted Rejected αArae Achernar

  20. Formation et Dissipation des Disques Achernar Vinicius, Zorec et al. (2005) Equilavent Width variations (EW) Double peak separation variations (DPS) DPSmax=460kms-1~2.vsin i DPSmin=160kms-1

  21. Outburst vr = 0.2 km.s-1 ρ(r) I r (R*) vx/vsini

  22. Formation et Dissipation des Disques Achernar Critical rotation Wind > 10R* Disk and Wind « independant » Outburst from 1991 to1995 Vr~0.2kms-1 Rmax~8R* (if keplerian) 3ème Phase? Nouvel Outburst Depuis 2002? AMBER LR (Imagerie) + AMBER HR (cinématique) Meilland et al. En preparation

  23. Disk creation and dissipation Start in 2000 (Periastron) Rdisk(2003)~10R* Vr~0.4kms-1 Keplerian? Multiples outburst? δSco Miroshnichenko et al. 2003 A&A 408,305

  24. Formation et Dissipation des Disques δSco Flux constant Outburst

  25. Conclusion

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