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AMBER observations of Be Stars Anthony Meilland And Philippe Stee.

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Presentation on theme: "AMBER observations of Be Stars Anthony Meilland And Philippe Stee."— Presentation transcript:

1 AMBER observations of Be Stars Anthony Meilland And Philippe Stee

2 Be Stars definition Active hot Stars : 8000K

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 Polar wind strength Effect of magnetic fields Disk open angle (Hydrostatic equilibrium, wind compressed disk) Variability : origin and role Pulsations Equatorial disk formation and dissipation (Be Be-Shell B normal) Continuous mass ejection or outbursts Overdensity rotation or precession (One-Armed Oscillation) Magnetic fields effect

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

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

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

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

8 α Ara Observed with AMBER geometry Meilland et al A&A

9 α Ara Observed with AMBER geometry Meilland et al A&A

10 α Ara Observed with AMBER geometry Meilland et al A&A

11 α Ara Observed with AMBER geometry Meilland et al A&A

12 V Φ >> V r V Φ ~ V r α Ara Observed with AMBER Kinematics : expansion or rotation (or both) Meilland et al A&A

13 V Φ >> V r V Φ ~ V r α Ara Observed with AMBER Kinematics : expansion or rotation (or both) Meilland et al A&A

14 Keplerian rotation ( β =0.48±0.05) Critical rotation V rot ~V c α Ara Observed with AMBER Kinematics : expansion or rotation (or both) Meilland et al A&A

15 Best Simeca model ρ equ ρ pol ~ V exp(eq) <10kms -1 V exp(pol) ~ kms -1 Φ equ Φ pol <10 R disk =32R * α Ara Observed with AMBER Meilland et al A&A

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

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

18 KINEMATICS κ CMa Non keplerian rotation ( β =0.3±0.1) Sub-critical rotation V rot ~0.52V c NO expansion (V Φ >> Vr ) Inhomogeneity aligned with major-axe? Meilland et al A&AAchernar Critical rotation No equatorial disk during VINCI obervations In 2002 Disk between 1991 and 1998? Domiciano de Souza et al. A&A Vinicius et al A&A

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

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

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

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

23 Disk creation and dissipation δ Sco Miroshnichenko et al A&A 408,305 Start in 2000 (Periastron) R disk (2003)~10R * V r ~0.4kms -1 Keplerian? Multiples outburst?

24 Formation et Dissipation des Disques δ Sco Flux constant Outburst

25 Conclusion


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