Open access

Performance comparison between
JWST/MIRI+NIRCam & VLT/SPHERE
for exoplanet detection
Charles Hanot, Olivier Absil, Jean Surdej
ARC meeting, 11February 2010
jeudi 11 février 2010
James Webb Space Telescope (JWST)
• Infrared-optimized 6.5 m telescope
• Detection of first galaxies
• Stars forming planetary systems
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JWST/ MIRI
• Mid-InfraRed Instrument (5-27µm)
• Imager + Spectrograph
• Equiped with coronagraphs for high dynamic imaging
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JWST/ NIRCam
• Near InfraRed Camera (0.6-2.3µm + 2.4-5 µm)
• Imager
• Equipped with coronagraphs for high dynamic imaging
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!"##"$
AB Pic b
θ Ori 1 C
17/03/2003
17/03/2003
17/03/2003
16/03/2003
AB Pic A
AB Pic b
θ Ori 1 C
05/03/2004
05/03/2004
05/03/2004
AB Pic A
AB Pic b
θ Ori 1 C
25/09/2004
25/09/2004
25/09/2004
VLT/SPHERE
• Extreme adaptive optics (XAO)
• Coronagraphs (1.4-2.4µm)
• Spectral differential imaging
AB Pic b
HIP 33632
03/12/2004
03/12/2004
18 × 30 s
5 × 30 s
3 × 20 s
12 × 10 s
J
H
Ks
NB1.75
S13
S13
S27
S13
coronagr
coronagr
coronagr
coronagr
NB1.75
H
H
S13
S13
S13
classical
coronagr
coronagr
2×5s
3 × 20 s
4 × 0.8 s
H+ ND
H
H
S13
S13
S13
classical
coronagr
coronagr
16 × 300 s
10 × 5 s
SHK
SHK
Spectroscopy
S54
Rλ = 550
S54
Rλ = 550
10 × 1 s
4 × 30 s
10 × 12 s
Chauvin et al. 2005
Table 2.
!"#$%&#!#'#(
Comp
AB Pic
AB Pic
a
From t
2003).
b
From a
)
*
+,
Fig. 1. Ks -band coronagraphic image of AB Pic A and b acquired on
17 March 2003 with an occulting mask of diameter 1.4"" .
jeudi 11 février 2010
S13 camera were found on 16 March 2003, 5 March 2004 and
25 September 2004 respectively at −0.05◦, 0.04◦, 0.20◦ east of
◦
of the at
spectrum
store the
spectrum
(Pickles
3. Com
To verif
Context and goals
MIRI GTO: short program proposal
 Well defined, well focused
 Immediate scientific return
Main goals
 Directly detect the smallest possible planets at
5-50 AU from main sequence stars
 Unveil new population of planets
 Follow-up: constrain theoretical cooling models
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Why M stars?
Most abundant stellar type
Planetary systems not well known
 Planet formation/migration similar to Sun-like stars?
Currently a hot topic
 RV and transit surveys starting
 Prospects for super-Earths in habitable zones
Low luminosity
 Fainter planets can be imaged at a given contrast
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Why young main sequence stars?
“Main sequence”
 Thick disks have disappeared
 Planetary systems mostly formed
“Young”
 Planets are still warm and luminous
○ Cooling models poorly constrained
 Moving groups and associations
○ Nearby (typically 20 – 50 pc)
○ Ages relatively well defined
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easier
Evolutionary models
Fortney et al. 2008
Hot start
Baraffe et al. 2003
Core accre5on
Fortney et al. 2008
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10 Myr
Scientific return
Detection at 11.4 µm
 Age known
planet temperature and mass from
models
 First statistics of low-mass planets
Follow-up with MIRI
 15.5 µm: model-independent temperature estimation
 10.65 µm: search for ammonia
Follow-up with NIRCam at 4.6 µm
 More constraints on theoretical models
Astrometric follow-up
dynamical mass
determination for close planets (< 5 AU)
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Illustrative result with MIRI
M0V,10pc, 12 Myr, 1h
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Sample and sensitivity
0.2”
1.0”
2.0”
Dist Age (pc) (Myr)
Sp type
V
a
AU
M
Mjup
a
AU
M
Mjup
a
AU
M
Mjup
a
AU
M
Mjup
AU Mic
9.9
12
M1Ve
8.8
2
0.50
5
0.30
10
0.16
25
0.10
TWA 8A
21.0
8
M3Ve
12.2
4
0.40
11
0.25
21
0.19
53
0.16
TWA 8B
21.0
8
M5
15.2
4
0.33
11
0.23
21
0.18
53
0.17
WW PsA
23.6
12
M4
12.2
5
0.50
12
0.30
24
0.21
59
0.20
CD‐57 1054
26.3
12
M0/1
10.0
5
0.80
13
0.50
26
0.25
66
0.23
V1005 Ori
26.7
12
M0.5V 10.1
5
0.80
13
0.50
27
0.25
67
0.23
TWA 12
32.0
8
M1Ve
12.9
6
0.80
16
0.45
32
0.26
80
0.25
CPD‐66 3080B
31.4
12
M3Ve
12.7
6
0.80
16
0.42
31
0.28
79
0.27
TWA 7
38.0
8
M2Ve
11.7
8
0.90
19
0.52
38
0.30
95
0.28
GJ 4020 A
24.0
50
M0
10.2
5
2.00
12
1.10
24
0.60
60
0.50
GJ 9809
24.9
50
M0
10.9
5
2.00
12
1.10
25
0.60
62
0.50
CT Tuc
37.5
30
M0Ve
11.5
7
1.70
19
0.95
37
0.55
94
0.50
Name
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0.5”
Comparison with NIRCam
MIRI better than NIRCam for planets <1.5’’ (~40AU)
Only MIRI can access planets <0.8’’ (~20AU)
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Comparison with SPHERE
2
C. HANOT, O. ABSIL, D. MAWET, P. RIAUD, D. DEFRÈRE AND J. SURDEJ
Most M stars too faint for SPHERE
SPHERE more sensitive <15AU
moving group - 12Myr, (ii) the Tucana-Horologium association - 30Myr and (iii) the AB Doradus
moving group - 50Myr. The visible and near infrared magnitudes of these stars are well known.
However, their magnitude in the N band is way more difficult to find. Therefore, as their spectral
types and thus their effective temperatures are known, we computed their N magnitude assuming
a blackbody distribution and scaling the resulting curve to mach the V and K magnitudes that are
well known (see Tab. 4).
3. Exoplanetary models
4
Absolute magnitude of companions for a system aged of 10MYr
24
SPHERE spectral band
MIRI 1st spectral band
MIRI 2nd spectral band
MIRI 3rd spectral band
22
Absolute Magnitude
20
18
16
0.5 MJup
1 MJup
2 MJup
3 MJup
4 MJup
5 MJup
6 MJup
7 MJup
8 MJup
9 MJup
10 MJup
14
12
10
0
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15
Wavelength [µ m]
Figure 1. Absolute magnitude of companions in a system aged of 10Myr using the
Baraffe et al. 2003 evolutionary models. The magnitudes for wavelengths above
5µm are obtained by computing the blackbody distribution at 15.5µm where the
brightness is supposed to be an almost perfect blackbody (no features) and by
interpolating the magnitudes between 5 and 15.5µm. (Hanot et al. 2009, in prep.)
The models used to assess the magnitudes of the exoplanets in these young stellar systems are
the one of Baraffe et al. 2003 for the giant exoplanets and the one of Baraffe et al. 2008 for
the exoplanets having a mass between Neptune and Jupiter. For the giant exoplanetary models,
the only
parameter
is the age of the system. The absolute magnitudes from the visible to the
jeudi
11 février
2010
M band, the effective temperature and the radius of the planets are then given as a function of
C. HANOT, O. ABSIL, D. MAWET, P. RIAUD, D. DEFRÈRE AND J. SURDEJ
Name
203
2884
2885
3003
12894
14082
14228
16978
17332
25457
29391
35850
98736
146624
164249
165189
172167
172555
181296
181327
195627
199143
207964
210027
217343
224392
GJ 226.2
GJ 466
GJ 842.2
Mov group
β Pic
Tuc - Hor
Tuc - Hor
Tuc - Hor
Tuc - Hor
β Pic
Tuc - Hor
Tuc - Hor
AB Dor
AB Dor
β Pic
β Pic
Castor
β Pic
β Pic
β Pic
Castor
β Pic
β Pic
β Pic
Tuc - Hor
β Pic
Tuc - Hor
Castor
AB Dor
Tuc - Hor
Castor
Castor
Castor
Dist (pc)
39.1
41
46
47
47.2
39.4
47.5
47
32.6
19.2
29.8
26.8
32
43.1
46.9
43.9
7.75
29.2
47.7
50.6
27.6
47.7
46.5
11.75
32.1
49
25
39.87
21
Age (Myr)
12
30
30
30
30
12
30
30
50-70
50-70
12
12
200
12
12
12
200
12
12
12
30
12
30
200
50-70
30
200
200
200
Sp Type
F2 IV
B9 V
A2 V
A0 V
F2 V
F5 V
B8 V
B9 V
G0+G5
F5 V
F0 V
F7/8 V
G5
A0 (V)
F5 V
A5 V
A0 V
A5 IV/V
A0 V
F5/6 V
F0 V
F8 V
F0 IV
F5 V
G3 V
A1 V
K8 V
M0 V
M0.5
Kmag
5.4
4.48
4.11
4.98
5.45
5.79
4.13
4.25
5.52
4.18
4.54
4.93
6.03
4.74
5.91
4.39
0.13
4.3
5.01
5.91
4.8
5.81
4.9
2.56
5.94
4.82
6.67
7.18
6.73
Nmag
5.12
4.2
4.13
4.87
5.23
5.83
3.8
4.13
5.43
4.24
4.29
5.08
6.47
4.59
5.83
4.5
0.1
4.27
4.87
5.84
4.7
5.99
4.8
2.85
5.89
4.77
6.65
6.96
6.86
Mass (10AU)
9.5 / 4
35 / 8
45 / 11
40 / 9
25 / 8
5.5 / 3.5
65 / 11
45 / 11
9/7
0.5 / 5.5
9.5 / 3.5
3/3
3/ 17 / 6
10 / 4.5
19 / 7
6/ 9.5 / 3.5
19 / 7
13 / 5
7.5 / 5
12 / 5
35 / 7
3/ 6/6
50 / 9
3/ 7.5/ 0.45/ -
Mass (20AU)
0.75 / 2.5
7.5 / 5.75
30 / 5.5
11 / 5.75
8/6
0.3 / 2
22 / 7.5
15 / 7.5
0.45 / 5.5
0.39 / 6
0.9 / 6.5
0.15 / 2
0.375 / 2 / 2.5
3/2
4/4
1/0.3 / 2.5
8.5 / 2.5
5 / 2.5
0.33 / 4.25
2.5 / 2.5
3 / 4.25
0.5 / 0.3 / 5
6 / 4.25
0.375 / 1/0.25 / -
Table 1. Table summarizing the sensitivity of both SPHERE and MIRI for extrasolar planet detection for two orbital distances of the companions: 10 and 20 AU.
The bold values correspond to SPHERE and the other one to MIRI. These masses
are specified in Jupiter masses. Hanot et al. 2009, in prep.
performances of the actual coronagraphic instrument available (NACO). These improved performance should allow us to take direct images of exoplanets. The observation spectral band is the
H-band. The main advantage of SPHERE with respect to MIRI is of course its angular resolution.
Indeed, with a working wavelength almost 10 times smaller (1.65µm instead of 11.4 µm) and a
slightly bigger telescope (8m instead of 6.5m), the angular resolution of SPHERE is an order of