Mass loss of evolved stars
Betlegeuse/PIONIER
Antares/PIONIER
CE Tau/PIONIER
Conclusion
About the angular diameter of red supergiant
stars
Miguel Montargès (IRAM)
VLTI Community Days
ESO Garching - March 9th 2017
Miguel Montargès (IRAM)
About the angular diameter of red supergiant stars
1/15
Mass loss of evolved stars
Betlegeuse/PIONIER
Antares/PIONIER
CE Tau/PIONIER
Conclusion
Stellar evolution
Miguel Montargès (IRAM)
About the angular diameter of red supergiant stars
2/15
Mass loss of evolved stars
Betlegeuse/PIONIER
Antares/PIONIER
CE Tau/PIONIER
Conclusion
Trigerring the RSG mass loss
Physical process remains unknown (no flares, no large pulsations)
Josselin & Plez (2007) suggested a convection triggered mass loss
Auriere et al. (2010) observed magnetic field ∼ 1 G
+ Airapetian et al. (2000): model Alfvén-wave triggered outflow
Miguel Montargès (IRAM)
About the angular diameter of red supergiant stars
3/15
Mass loss of evolved stars
Betlegeuse/PIONIER
Antares/PIONIER
CE Tau/PIONIER
Conclusion
Trigerring the RSG mass loss
Physical process remains unknown (no flares, no large pulsations)
Josselin & Plez (2007) suggested a convection triggered mass loss
Auriere et al. (2010) observed magnetic field ∼ 1 G
+ Airapetian et al. (2000): model Alfvén-wave triggered outflow
→ Study of the photosphere + CSE
Miguel Montargès (IRAM)
About the angular diameter of red supergiant stars
3/15
Mass loss of evolved stars
Betlegeuse/PIONIER
Antares/PIONIER
CE Tau/PIONIER
Conclusion
Spatial scales
(P. Kervella)
Miguel Montargès (IRAM)
About the angular diameter of red supergiant stars
4/15
Mass loss of evolved stars
Betlegeuse/PIONIER
Antares/PIONIER
CE Tau/PIONIER
Conclusion
PIONIER monitoring of Betelgeuse (α Ori)
VLTI/PIONIER observations (4 telescopes, H band, low spectral
resolution, R = 40)
4 epochs of monitoring: Jan. 2012, Feb. 2013, Jan. 2014 and
Nov. 2014
Only the compact array configuration (baseline length ∈ [11; 36 m])
⇒ Montargès et al. (2016), A&A, 588, A130
Miguel Montargès (IRAM)
About the angular diameter of red supergiant stars
5/15
Mass loss of evolved stars
Betlegeuse/PIONIER
Antares/PIONIER
CE Tau/PIONIER
Conclusion
Betelgeuse@PIONIER: Shape of the visibilities (2013)
30
0.05
20
0.04
Squared visibility
v (m)
10
0
10
0.02
0.01
20
30
30
0.03
20
10
0
u (m)
10
20
30
0.00
20
40
60
80
Spatial frequency (arcsec−1 )
100
120
Consistent between the 4 epochs (3 different features to avoid
detector saturation)
Miguel Montargès (IRAM)
About the angular diameter of red supergiant stars
6/15
Mass loss of evolved stars
Betlegeuse/PIONIER
Antares/PIONIER
CE Tau/PIONIER
Conclusion
Betelgeuse@PIONIER: Shape of the visibilities (2013)
0 (N)
25
20
15
10
5
90
(E)
270
(W)
Limb-darkened disk fit:
44.21 vs 48.56 mas
⇒ 10% difference !
180 (S)
Miguel Montargès (IRAM)
About the angular diameter of red supergiant stars
7/15
Mass loss of evolved stars
Betlegeuse/PIONIER
Antares/PIONIER
CE Tau/PIONIER
Conclusion
Betelgeuse@PIONIER: Shape of the visibilities (2013)
0 (N)
25
20
15
10
5
90
(E)
270
(W)
Limb-darkened disk fit:
44.21 vs 48.56 mas
⇒ 10% difference !
AND litterature value ∼ 42 mas
180 (S)
Miguel Montargès (IRAM)
About the angular diameter of red supergiant stars
7/15
Mass loss of evolved stars
Betlegeuse/PIONIER
Antares/PIONIER
CE Tau/PIONIER
Conclusion
Betelgeuse@PIONIER: Shape of the closure phase (2013)
200
150
Closure phase (degree)
100
50
0
50
100
150
200
40
50
60
70
80
90
Maximum spatial frequency (arcsec−1 )
100
110
120
Strong signal
Incompatible with elliptical model
Miguel Montargès (IRAM)
About the angular diameter of red supergiant stars
8/15
Mass loss of evolved stars
Betlegeuse/PIONIER
Antares/PIONIER
CE Tau/PIONIER
Conclusion
Betelgeuse@PIONIER: LDD model + gaussian hotspot
Chiavassa et al. (2009, 2010) showed that convection can displace
the nulls of the visibility function (as a function of P. A.)
→ Difficulty: angular diameter cannot be inferred from the first null
anymore
Miguel Montargès (IRAM)
About the angular diameter of red supergiant stars
9/15
Mass loss of evolved stars
Betlegeuse/PIONIER
Antares/PIONIER
CE Tau/PIONIER
Conclusion
Betelgeuse@PIONIER: LDD model + gaussian hotspot
Chiavassa et al. (2009, 2010) showed that convection can displace
the nulls of the visibility function (as a function of P. A.)
→ Difficulty: angular diameter cannot be inferred from the first null
anymore
Good agreement + angular diameter consistent with
literature∼ 43 mas)
Miguel Montargès (IRAM)
About the angular diameter of red supergiant stars
9/15
Mass loss of evolved stars
Betlegeuse/PIONIER
Antares/PIONIER
CE Tau/PIONIER
Conclusion
Betelgeuse@PIONIER: LDD model + gaussian hotspot
Consistent on the 4 epochs
B Photocenter displacement up to 2 mas (π ∼ 6 mas)
Spots already observed on Betelgeuse (see Haubois et al. 2009, Ravi
et al. 2011, Ohnaka et al. 2011)
Miguel Montargès (IRAM)
About the angular diameter of red supergiant stars
9/15
Mass loss of evolved stars
Betlegeuse/PIONIER
Antares/PIONIER
CE Tau/PIONIER
Conclusion
Betelgeuse@PIONIER: LDD model + gaussian hotspot
Consistent on the 4 epochs
B Photocenter displacement up to 2 mas (π ∼ 6 mas)
Spots already observed on Betelgeuse (see Haubois et al. 2009, Ravi
et al. 2011, Ohnaka et al. 2011)
Consistent with spectro-polarimetric observations at TBL/NARVAL
(Aurière et al. 2016)
Miguel Montargès (IRAM)
About the angular diameter of red supergiant stars
9/15
Mass loss of evolved stars
Betlegeuse/PIONIER
Antares/PIONIER
CE Tau/PIONIER
Conclusion
Antares@PIONIER
VLTI/PIONIER observations (4 telescopes, H band, low spectral
resolution, R = 40)
3 different configurations (baseline lengths : 11-150 m)
⇒ Montargès et al. subm., A&A
150
1.0
0.9
100
0.8
0.5
0.4
50
q
V (m)
0.6
0
Visibility
0.7
50
0.3
0.2
100
0.1
150
150
Miguel Montargès (IRAM)
100
50
0
U (m)
50
100
150
0.0
About the angular diameter of red supergiant stars
10/15
Mass loss of evolved stars
Betlegeuse/PIONIER
Antares/PIONIER
CE Tau/PIONIER
Conclusion
Antares@PIONIER: dataset
Squared visibility
100
10
1
10
2
10
3
10
4
10
5
10
6
10
7
Data
50
Miguel Montargès (IRAM)
100
150
200
250
Spatial frequency (arcsec 1)
300
350
About the angular diameter of red supergiant stars
400
11/15
Mass loss of evolved stars
Betlegeuse/PIONIER
Antares/PIONIER
CE Tau/PIONIER
Conclusion
Antares@PIONIER: 1st and 2nd lobe
27.5
112
25.0
22.5
Position angle ( ◦ )
Squared visibility
10 -2
20.0
40
30
20
10
0
10
20
30
40
10 -3
10 -425
Miguel Montargès (IRAM)
30
60 40 20 0 20 40 60
35
40
Spatial frequency (arcsec−1 )
45
104
96
88
17.5
80
15.0
72
12.5
64
10.0
56
50
About the angular diameter of red supergiant stars
12/15
Mass loss of evolved stars
Betlegeuse/PIONIER
Antares/PIONIER
CE Tau/PIONIER
Conclusion
Antares@PIONIER: 1st and 2nd lobe
0 (N)
20.0
17.5
15.0
12.5
10.0
7.5
5.0
2.5
90
(E)
270
(W)
LDD diameters (at 1.61 µm):
37.70-39.03 mas
⇒ 4% difference
AND does not fit the closure phases !
180 (S)
Miguel Montargès (IRAM)
About the angular diameter of red supergiant stars
12/15
Mass loss of evolved stars
Betlegeuse/PIONIER
Antares/PIONIER
CE Tau/PIONIER
Conclusion
Antares@PIONIER: modeling
B Weak signal compared to Betelgeuse → small spots ?
B Angular resolution ∼ 1/16th of the stellar diameter !
Miguel Montargès (IRAM)
About the angular diameter of red supergiant stars
13/15
Mass loss of evolved stars
Betlegeuse/PIONIER
Antares/PIONIER
CE Tau/PIONIER
Conclusion
Antares@PIONIER: modeling
B Weak signal compared to Betelgeuse → small spots ?
B Angular resolution ∼ 1/16th of the stellar diameter !
⇒ Modeling using random distribution of spots with a fixed size !
Miguel Montargès (IRAM)
About the angular diameter of red supergiant stars
13/15
Mass loss of evolved stars
Betlegeuse/PIONIER
Antares/PIONIER
CE Tau/PIONIER
Conclusion
Antares@PIONIER: modeling
B Weak signal compared to Betelgeuse → small spots ?
B Angular resolution ∼ 1/16th of the stellar diameter !
⇒ Modeling using random distribution of spots with a fixed size !
Best match:
Gaussian spot distributions with a FWHM of 17 and 2 mas (not
resolved !)
LDD diameter: 37.89 ± 0.10 mas at 1.61 µm
χ2 (V 2 + CP) as low as 28 (627 for best LDD alone)
Miguel Montargès (IRAM)
About the angular diameter of red supergiant stars
13/15
Mass loss of evolved stars
Betlegeuse/PIONIER
Antares/PIONIER
CE Tau/PIONIER
Conclusion
On going DDT program on CE Tau with PIONIER
100
140
60
V (m)
0
80
20
60
40
60
40
100
75
50
25
0
U (m)
25
50
75
PA (deg)
100
20
Squared visibility
120
40
10
1
10
2
10
3
10
4
10
5
100
20
0
50
100
150
200
Spatial frequency (arcsec 1)
250
300
At 1.62 µm:
θLDD = 10.07 ± 0.05 mas
χ2 = 10.89
Miguel Montargès (IRAM)
About the angular diameter of red supergiant stars
14/15
Mass loss of evolved stars
Betlegeuse/PIONIER
Antares/PIONIER
CE Tau/PIONIER
Conclusion
Conclusions
30
0.05
20
0.04
Squared visibility
v (m)
10
0
10
0.02
0.01
20
30
30
0.03
20
10
0
u (m)
10
20
30
0.00
20
40
60
80
Spatial frequency (arcsec−1 )
100
120
What would we have concluded with only
the red (48.56 mas) or blue (44.21 mas) baselines ?
Miguel Montargès (IRAM)
About the angular diameter of red supergiant stars
15/15