wind mass transfer in binaries and its effect on orbital evolution...wind mass transfer in binaries...
TRANSCRIPT
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Windmasstransferinbinariesanditseffectonorbitalevolution
OnnoPolsEdwinvanderHelmIntiPelupessy
SimonPortegies-Zwart
MarthaIreneSaladino
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Period distribution for sun-like stars
Closebinary=>orbitshrinksandcircularizesWidebinary=>orbitwidens
Motivation
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a) Primary star = AGB star:
Model
Mass loss rate 10-7-10-5 MSun/yr Slow winds ~ 5-30 km/s no Bondi Hoyle accretion
b) Secondary star = Low mass main sequence star.
Portegies-Zwart+(2013); Pelupessy+(2013); van Elteren+(2014)Cooling
STELLAR_WIND.PY
Bowen (1988) + Schure (2009)
van der Helm, Saladino, + (in prep)
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a = 5 AU
M1=3 MM2=1.5 MM1=1e-06 M /yr
vorb = 28.2 km/s
�
� �
v(r)3 R
vwind = 10 km/s vwind = 15 km/s vwind = 30 km/s vwind = 150 km/s
Casestudies
.
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v∞=15km/s
Results
v∞=30km/s
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Accretiondisk
0 5 10 15 20 25 30 35 40 45Time [yr]
0
1
2
3
4
5
Mas
s[M
�]
1e-7
v∞=15km/s
v∞=10km/s
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ȧ
a= �2Ṁd
Md
1� �q � ⌘(1� �)(q + 1)� (1� �) q
2(q + 1)
�
OrbitalevolutionFrom angular momentum conservation:
�� �⌘
Fraction of mass accreted
� =Ṁ2
Ṁ1
Specific angular momentum of mass lost
⌘ ⌘ 1a2⌦
J̇
Ṁ
!
loss
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� =Ṁ2
Ṁ1Massaccretionrate
e.g. Mohamed (2007)
Theuns+(1996)
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⌘ ⌘ 1a2⌦
J̇
Ṁ
!
loss
Specificangularmomentumloss
⌘ =
✓M2
M1 +M2
◆2 Isotropic mass loss
Jahanara+ (2005), Chen+ (2017) Different method, similar results
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Predictionontheorbits
ȧ
a= � Ṁ1
M1 +M2
ȧ
a= �2Ṁd
Md
1� �q � ⌘(1� �)(q + 1)� (1� �) q
2(q + 1)
�
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Directlymeasuringorbitalevolutionv∞ = 150 km/s v∞ = 15 km/s
a [A
U]
✓da
dt
◆
simulation
= �1.03⇥ 10�6AU yr�1
✓da
dt
◆= �3.8⇥ 10�6AU yr�1
✓da
dt
◆= 1.11⇥ 10�6AU yr�1
a [A
U]
✓da
dt
◆
simulation
= 1.04⇥ 10�6AU yr�1
expected expected
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Conclusions•Atlowvelocityratiosanaccretiondiskisformed.•Thepresenceofanaccretiondiskinducesvariabilityinthemassaccretedbythecompanion.
• Ifv∞/vorb>1⇒βsmallandηsmall⇒orbitwidens.• Ifv∞/vorb<1⇒βlargeandηlarge⇒orbitshrinks.•This may explain the orbital sizes seen in post-AGBbinaries.
• ItwillalsolikelyincreasethenumberofsystemsgoingtoCE.