Be stars observations with VEGA/CHARAchara.gsu.edu/files/2010Meeting/30.Delaa.pdfBe stars...
Transcript of Be stars observations with VEGA/CHARAchara.gsu.edu/files/2010Meeting/30.Delaa.pdfBe stars...
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CHARA Collaboration Year-Six Science Review
Be stars observations with VEGA/CHARAOmar Delaa : PhD, Observatoire de la Côte
d’AzurPhilippe Stee : Observatoire de la Côte d’azurJuan Zorec : Institut d’Astrophysique de Paris
VEGA consortium
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CHARA Collaboration Year-Six Science Review
VEGA / CHARA in the French Astronomical revue “Ciel Et Espace” !
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CHARA Collaboration Year-Six Science Review
Presence of a circumstellar environment around Be stars
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CHARA Collaboration Year-Six Science Review
Problematic around Be Stars
What is the Origin of the formation of disk around Be stars ?
Five physical mechanisms possible :
Rotation Stellar winds pulsations Magnetism Binarity
Constrain the Geometry and kinematic of the disk by spectro - interferometry
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CHARA Collaboration Year-Six Science Review
Spectro interferometry (1)• The geometry study
Geometry
In the whole line
(Doppler effect)
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CHARA Collaboration Year-Six Science Review Spectro-interferometric study of Be stars disks
(Doppler Effect)
In the whole line Narrow spectral bandwidth across the line
Variation of the visibility modulus and phase as a function of wavelength
Geometry + Kinematics
GeometryExpansion/rotation, rotational law,
inhomogeneities…
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CHARA Collaboration Year-Six Science Review
Disk Geometry and kinematic of three Be Stars
Stee & Meilland (2009) , VLTI / MIDI
Fast Rotation Fast Rotation + other physical processes (Binarity ?)
Fast Rotation for the formation and binarity for dissipation of the disk
Hα line more intense than Brγ line Study in the visible Wavelength
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CHARA Collaboration Year-Six Science Review
VEGA/CHARA Targets
ψ Per Vsini = 297 km/s B5Ve d=214 pcγCas Vsini = 243 km/s B0 IVe d=187 pc48 Per Vsini = 198 km/s B3 Ve d=169 pcχ Oph Vsini = 139 km/s B1.5 Ve d=150 pc
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CHARA Collaboration Year-Six Science Review
: Disk orientation
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CHARA Collaboration Year-Six Science Review
Model• Star + Circumstellar disk only in rotation
– Modeling of Visibility and phases as function of wavelength• Output parameter :• Stellar Inclination, Stellar radii, Øenv in line,Øenv in
continuum, P.A.
• Kinematic of the disk :r = Distance to the center of the
star
β = Free parameter
= Stellar rotational velocity
= Stellar radius
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CHARA Collaboration Year-Six Science Review
W1W2
48 Per results around Hα line
V
φWavelength
S1S2Bad fitting
Multiple scattering effect
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CHARA Collaboration Year-Six Science Review
48 Per parameters around Hα line
Stellar rotational velocity (km/s)
Exponent β of the rotationalvelocity law
440 ± 50 (Critical velocity) -0.5 ± 0.1
Disk in Keplerian rotation
inclination (deg)
R star (Rsolar)
Øenv in line (Rstellar)
Øenv in continuum
(Rstar)
P.A. (degree
)
% of emission scattered in the
line 30 ± 5 4.8 ± 0.5 10 ± 2 ? 125 ± 5 40 ± 5
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CHARA Collaboration Year-Six Science Review
W1W2
ψ Per results around Hα lineBad fitting
V
φ
Wavelength
S1S2Multiple scattering effect
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CHARA Collaboration Year-Six Science Review
ψ Per results around Hα line
Stellar rotational velocity (km/s)
exponent β of the rotational velocity law
400 ± 50 (Critical Velocity) -0.37 ± 0.05
Disk doesn’t appear in Keplerian rotation
inclination (deg)
R star (Rsolar)
Øenv in line
(Rstellar)
Øenv in continuum (Rstar)
P.A. (degree
)
% of emission
scattered in the line
78 ± 105.9 ±0.59 20 ± 7.5 10 ± 10 108 ± 1 40 ± 5
Limitation of the model
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CHARA Collaboration Year-Six Science Review
With
γCas results around Hα line
Baseline S1S2 = 1
= 0.1 + 0.9
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CHARA Collaboration Year-Six Science Review
χOph results around Hα line
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CHARA Collaboration Year-Six Science Review
Conclusions on Be stars study• 48 Per :
• Fast rotation (critical velocity) • Disk in Keplerian rotationConsistent with αArae study
• Psi Per• Fast rotation (critical velocity) • Disk doesn’t appear in Keplerian rotation ( Not
consistent with the previous results on 48 Per and αArae) Limitation of the model
• χ oph and γCas : poor uv coverage plan
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CHARA Collaboration Year-Six Science Review
Perspective on Be stars• Complete the uv coverage plan for χ Oph and
γ Cas (Data remain to be reduced )• Precise modeling with SIMECA code• Long baselines observation of γ Cas in the continuum :
• Photospheric size of γ Cas • Contribution of the envelope
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CHARA Collaboration Year-Six Science Review
Observations of interacting massive stars with CHARA/VEGA
Massive binary systems upsilon Sgr, binary system harboring an hydrogen
deficient star (HdB star) beta Lyr: binary system with current mass-exchange
υ SgrβLyr
υ Sgr: O. Chesneau, D. Bonneau, P. Koubsky, D. Mourard , P. Steeβ Lyrae: D. Bonneau , O. Chesneau, D. Mourard , P. Stee
since 2008 VEGA/CHARA interferometric observations
2T , B = 34mains goals Shape and size of the Hα emitting region ?Morpholog y of the binary system?
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CHARA Collaboration Year-Six Science Review
2008 CHARA/VEGA observations of β Lyrae
In the continum β Lyr is unresolved at any orbital phase
Hα: significantly resolved at any Φorb, photocenter shift correlated with Φ orb
Hβ: resolved at some Φorb, suspicious of photocenter shifts
HeI (6678 A) : marginally resolved at any Φ orb,, no clear photocenter shift detected
Base S1S2 MR 656 – 487 nm Four orbital phases
Preliminary results
“Spectro-interferometric observations of interacting massive stars with VEGA/CHARA”D. Bonneau, O. Chesneau, D. Mourard & P. Stee, Presentation at the conference " Binaries - Keys to comprehension of the Universe, Brno, 8-12 June 2009, to be published in ASP Conference Series.
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CHARA Collaboration Year-Six Science Review
Φorb= 0.312
Differential Spectral analysis of β Lyrae observations2009 07 25
baseline S1S2 β Lyr
γ Lyr
H α
Wavelength →
ϕ diff
(λ)
V(λ
)/V
con
2σ
2σ
TU 04h 14 mn Bp = 34.08 m Arg = 6.6°
source slightly resolved in Hα with Vline / Vcont = 0.75 ± 0.08 slight differential phase offset in Hα with ϕdiff = + 15 ° ± 5 °
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CHARA Collaboration Year-Six Science Review
Φorb= 0.326
Differential Spectral analysis of β Lyrae observations2009 07 25
baseline S1S2 β Lyr
γ Lyr
H α
Wavelength →
ϕ diff
(λ)
V(λ
)/Vco
n
2σ
2σ
TU 08h 48 mn Bp = 33.51 mArg = -28.0°
source slightly resolved in Hα with Vline / Vcont = 0.80 ± 0.05marginal differential phase offset in Hα with ϕdiff = - 5 °± 5 °
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CHARA Collaboration Year-Six Science Review
Φorb= 0.404
Differential Spectral analysis of β Lyrae observations2009 07 26
baseline E1E2
TU 09h 09 mn Bp = 58.62m Arg = -156.0°
β Lyr
γ Lyr
H α
Wavelength →ϕ diff
(λ)
V(λ
)/V
con
2σ
2σ
source resolved in Hα with Vline / Vcont = 0.60 ± 0.12 differential phase offset in Hα with ϕdiff = + 25 ± 9 °
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CHARA Collaboration Year-Six Science Review
Analysis of the β Lyrae data
Model of the photocenter position in V-band computed from Ak et al. (2007)
0,0
0,2
0,4
0,6
0,8
1,0
-0,2 -0,1 0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0
star2 Disk
Star1 Donor
Φorb
Phot
ocen
ter d
ispl
acm
ent
Paper in preparation Bonneau et al
Comparison with the work done with NPOI
V2 [
Hα]
B/λ [Mλ]
From Schmitt et al. (2009)
VEGA/CHARAR = 1650
~ NS direction
NPOI R = 44
~ EW direction
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CHARA Collaboration Year-Six Science Review
THANK YOU
Los Angeles from Mount Wilson Observatory
David Jurasevich