AMBER observations of Be Stars Anthony Meilland And Philippe Stee.
-
Upload
jesse-brake -
Category
Documents
-
view
217 -
download
2
Transcript of AMBER observations of Be Stars Anthony Meilland And Philippe Stee.
AMBER observations of AMBER observations of Be StarsBe Stars
Anthony MeillandAnd Philippe Stee
Be Stars definitionBe 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
Questions about Be starsQuestions 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
Why using differential interferometryWhy using differential interferometryTo study Be stars?To study Be stars?
Rot
Exp
Results and futures observationsResults and futures observations
α Arae (MIDI + AMBER)α Arae (MIDI + AMBER)
Achernar (VINCI)Achernar (VINCI)
Κ CMA (AMBER)Κ CMA (AMBER)
Coming soon!Coming soon!New AMBER + MIDINew AMBER + MIDI
Coming not so soon Coming not so soon But we hope not too late!But we hope not too late!
New AMBERNew AMBER
δ Sco δ Sco AMBERAMBER
B=79 m , PA = 55°B=79 m , PA = 55°
8-13.5μm Visibilities8-13.5μm Visibilities
B=102 m , PA = 7°B=102 m , PA = 7°
αα Ara Observed with MIDIAra Observed with MIDI
unresolvedSmaller than what we expected
(<3mas for UD or <7mas US+UD)
Chesneau, Meilland et. Al A&A 2005
Companion at 32R*?
Short term Spectroscopic variationsShort term Spectroscopic variations
Disk truncation at 22R* ?
αα Ara Observed with AMBERAra Observed with AMBER
Meilland et al. 2007 A&A
Enveloppe ~40% total flux at 2μm
No significant envelope size variation
Between 2 and 13μm
Envelope extensionEnvelope extension
αα Ara Observed with AMBERAra Observed with AMBERgeometrygeometry
Meilland et al. 2007 A&A
αα Ara Observed with AMBERAra Observed with AMBERgeometrygeometry
Meilland et al. 2007 A&A
αα Ara Observed with AMBERAra Observed with AMBERgeometrygeometry
Meilland et al. 2007 A&A
αα Ara Observed with AMBERAra Observed with AMBERgeometrygeometry
Meilland et al. 2007 A&A
VΦ >> Vr VΦ ~ Vr
αα Ara Observed with AMBERAra Observed with AMBERKinematics : expansion or rotation (or both)Kinematics : expansion or rotation (or both)
Meilland et al. 2007 A&A
VΦ >> Vr VΦ ~ Vr
αα Ara Observed with AMBERAra Observed with AMBERKinematics : expansion or rotation (or both)Kinematics : expansion or rotation (or both)
Meilland et al. 2007 A&A
Keplerian rotation (β =0.48±0.05)
Critical rotation Vrot~Vc
αα Ara Observed with AMBERAra Observed with AMBERKinematics : expansion or rotation (or both)Kinematics : expansion or rotation (or both)
Meilland et al. 2007 A&A
Best Simeca modelBest Simeca model
ρequ
ρpol
~10-100
Vexp(eq)<10kms-1
Vexp(pol)~100-1000kms-1
Φequ
Φpol
<10
Rdisk =32R*
αα Ara Observed with AMBERAra Observed with AMBER
Meilland et al. 2007 A&A
Disk and Wind Disk and Wind
Achernar (VINCI)Achernar (VINCI)
5% total flux
No equatorial disk (<5R*)
Kervella et Domiciano de Souza. 2006 A&A
ΚΚ CMA (AMBER) CMA (AMBER)
No polar wind detected
Poorly resolved
Meilland et al. 2007 A&A
Equatorial disk : 50% of ftot at 2μm
Rdisk = 23R*
Disk and wind Disk and wind
Polar wind ( α Arae and Achernar)
Ljet>10R*
Fjet~1-5%F*
different mechanisms produce thepolar wind and the Equatorial disk ?
Disk open angle?
Wind open angle?
And Between?
Permanent Equatorial disk ( α Arae and κ Cma )
Rdisk~20-30 R*
Fdisk(K)~0.5Ftot
(also spectroscopic clues of a non permanent disk around Achernar 8R*)
KINEMATICSKINEMATICS
κκ CMaCMa
Non keplerian rotation (β =0.3±0.1)
Sub-critical rotation Vrot~0.52Vc
NO expansion (VΦ >> Vr )
Inhomogeneity aligned with major-axe?
Meilland et al. 2007 A&A
AchernarAchernar
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. 2005 A&A
NEXT?NEXT?
Image reconstruction with AMBERImage reconstruction with AMBER4 Complete observation nights avec each of the 4 «triplets» available for P794 Complete observation nights avec each of the 4 «triplets» available for P79
PSF (72 bases ATs)
α Arae Achernar
Accepted Rejected
Formation et Dissipation des DisquesFormation et Dissipation des Disques
Vinicius, Zorec et al. (2005)
Double peak separation variations (DPS)
DPSmax=460kms-1~2.vsin i
DPSmin=160kms-1
Equilavent Width variations (EW)
Achernar
vr = 0.2 km.s-1
r (R*)
ρ(r)
vx/vsini
I
Outburst
Formation et Dissipation des DisquesFormation et Dissipation des DisquesAchernar
Disk and Wind « independant »
Outburst from 1991 to1995
Nouvel Outburst Depuis 2002?
3ème Phase?
Vr~0.2kms-1
Rmax~8R* (if keplerian)
Wind > 10R*
Critical rotation
AMBER LR (Imagerie) + AMBER HR (cinématique)
Meilland et al. En preparation
Disk creation and dissipationDisk creation and dissipationδ Sco
Miroshnichenko et al. 2003 A&A 408,305
Start in 2000 (Periastron)
Rdisk(2003)~10R*
Vr~0.4kms-1
Keplerian?
Multiples outburst?
Formation et Dissipation des DisquesFormation et Dissipation des Disquesδ Sco
Flux constant
Outburst
ConclusionConclusion