Astrometric search for extrasolar planets

Astrometric search for extrasolar planets
Tristan Röll
Ralph Neuhäuser, Andreas Seifahrt, Guillermo Torres,
Rainer Köhler, Jacob Bean
Astrophysikalisches Institut und Universitäts - Sternwarte Jena
Young Planetary Systems Workshop,
Jena 2010
Tristan Röll (AIU Jena)
Astrometric search for exoplanets
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Exoplanet Detection - Methods
Accretion
on star
Planet Detection
Methods
Total: 429 planets
February 2010
Dynamical effects
??
Photometry
Timing
(ground)
Decreasing
planet mass
Self-accreting
planetesimals
Miscellaneous
Radio
emission
Microlensing
Imaging
Astrometry
Reflected/
blackbody
Disks
Pulsars
White
dwarfs
10M J
MJ
10M E
Binary
eclipses/
other
Radial
velocity
Radio
Astrometric
Photometric
Space
interferometry
(infrared/optical)
Optical
Ground
Space
Ground
Resolved
imaging
Space
Millisec
Search
for life
ME
4 planets discovered
(2 systems)
6
11
1
Slow
399 planets observed
(339 systems,
41 multiple)
Existing capability
10 planets discovered
(9 systems,
1 multiple)
Projected (10-20 yr)
Magnetic
superflares
n = systems; ? = uncertain
Free
floating
Ground
(adaptive
optics)
Transits
49
6
Ground
14
Timing
residuals
Space
63 planets discovered
(69 observed)
Discoveries
Follow-up detections
(diagram by M. Perryman)
Tristan Röll (AIU Jena)
Astrometric search for exoplanets
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Astrometric Signal
companion
to observer
astrometric signal
awobble [AU] = acomp [AU]
Mcomp
Mstar
Star
Tristan Röll (AIU Jena)
Astrometric search for exoplanets
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Astrometric Signal
companion
to observer
awobble [AU] = acomp [AU]
astrometric signal
Mcomp
Mstar
Star
Astrometric Signal (circular orbit)
Θ [mas] = 2 × awobble [mas] = 1.91 ×
Tristan Röll (AIU Jena)
acomp [pc] Mcomp [M ]
[AU] d [MJ ] Mstar
Astrometric search for exoplanets
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Astrometric Signal
companion
to observer
awobble [AU] = acomp [AU]
astrometric signal
Mcomp
Mstar
Star
Astrometric Signal (circular orbit)
Θ [mas] = 2 × awobble [mas] = 1.91 ×
acomp [pc] Mcomp [M ]
[AU] d [MJ ] Mstar
Example
Jupiter with Sun seen from 5 pc / 100 pc :
Earth with Sun seen from 5 pc:
Tristan Röll (AIU Jena)
Astrometric search for exoplanets
Θ = 2 mas / 0.1 mas
Θ = 1.2 µas
3 / 24
Exoplanet Detection - Sensitivity
102
(minimum) mass [MJup]
101
Jupiter
100
Saturn
10-1
Θ(50 pc) = 1 mas
Θ(10 pc) = 100 µas
Θ(5 pc) = 1 µas
K = 10 m/s
K = 1 m/s
K = 10 cm/s
∆F / F ' 1 %
∆F / F ' 0.1 %
∆F / F ' 0.01 %
Neptune
10-2
10-3
10-2
1 day
23.8 %
13.8 ◦
1 week
6.5 %
3.7 ◦
10-1
1 month
2.5 %
1.4 ◦
Earth
1 year
0.5 %
0.3 ◦
100
10 years
0.1 %
0.1 ◦
semi-major axis [AU]
101
50 years
300 years
102
(data from exoplanet.eu)
Tristan Röll (AIU Jena)
Astrometric search for exoplanets
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First Detection of an Astrometric Companion
Friedrich Wilhelm Bessel (1784-1846)
1844
periodic perturbation in the proper motions of Sirius and Procyon
Conclusion
existence of unseen companion orbiting the star
Sirius A, Sirius B
Tristan Röll (AIU Jena)
Astrometric search for exoplanets
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Peter van de Kamp
Tristan Röll (AIU Jena)
Astrometric search for exoplanets
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Peter van de Kamp
Sproul refractor (diameter: 61 cm, focal length: 10.9 m)
Tristan Röll (AIU Jena)
Astrometric search for exoplanets
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Peter van de Kamp
Sproul refractor (diameter: 61 cm, focal length: 10.9 m)
never confirmed by other groups (Gatewood et al., 1973)
Tristan Röll (AIU Jena)
Astrometric search for exoplanets
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Peter van de Kamp
Sproul refractor (diameter: 61 cm, focal length: 10.9 m)
never confirmed by other groups (Gatewood et al., 1973)
detection of systematic errors (Hershey, 1973)
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Astrometric search for exoplanets
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Spaced based Astrometry
Hubble Space Telescope
(launch: 1990)
Currently the only telescope, which already delivers successful
applications of astrometry regarding exoplanets.
Tristan Röll (AIU Jena)
Astrometric search for exoplanets
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Spaced based Astrometry
Hubble Space Telescope
(launch: 1990)
Currently the only telescope, which already delivers successful
applications of astrometry regarding exoplanets.
Gl 876 b
(Benedict et al., 2002)
Tristan Röll (AIU Jena)
Astrometric search for exoplanets
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Spaced based Astrometry
Hubble Space Telescope
(launch: 1990)
Currently the only telescope, which already delivers successful
applications of astrometry regarding exoplanets.
Gl 876 b
(Benedict et al., 2002)
55 Cnc d
(Mc Arthur et al., 2004)
Tristan Röll (AIU Jena)
Astrometric search for exoplanets
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Spaced based Astrometry
Hubble Space Telescope
(launch: 1990)
Currently the only telescope, which already delivers successful
applications of astrometry regarding exoplanets.
Gl 876 b
(Benedict et al., 2002)
55 Cnc d
(Mc Arthur et al., 2004)
Epsilon Eridani b
(Benedict et al., 2006)
Tristan Röll (AIU Jena)
Astrometric search for exoplanets
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Spaced based Astrometry
HD 33636 b
RV planet candidate with
M sin i = 9.3 MJ
Tristan Röll (AIU Jena)
Astrometric search for exoplanets
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Spaced based Astrometry
HD 33636 b
Bean et al. 2007
RV planet candidate with
M sin i = 9.3 MJ
determined with astrometry a true
mass of Mtrue = 142 ± 11 MJ
Tristan Röll (AIU Jena)
Astrometric search for exoplanets
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Astrometric Exoplanet Search at the AIU Jena
Targets
nearby stellar multiple systems (distance < 100 pc)
Tristan Röll (AIU Jena)
Astrometric search for exoplanets
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Astrometric Exoplanet Search at the AIU Jena
Targets
nearby stellar multiple systems (distance < 100 pc)
Telescope and Instruments
Tristan Röll (AIU Jena)
Astrometric search for exoplanets
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Astrometric Exoplanet Search at the AIU Jena
Targets
nearby stellar multiple systems (distance < 100 pc)
Telescope and Instruments
single 8 m apertures (VLT and SUBARU)
Tristan Röll (AIU Jena)
Astrometric search for exoplanets
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Astrometric Exoplanet Search at the AIU Jena
Targets
nearby stellar multiple systems (distance < 100 pc)
Telescope and Instruments
single 8 m apertures (VLT and SUBARU)
AO assisted NIR imager
Tristan Röll (AIU Jena)
Astrometric search for exoplanets
9 / 24
Astrometric Exoplanet Search at the AIU Jena
Targets
nearby stellar multiple systems (distance < 100 pc)
Telescope and Instruments
single 8 m apertures (VLT and SUBARU)
AO assisted NIR imager
NIR narrow band filter
Tristan Röll (AIU Jena)
Astrometric search for exoplanets
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Astrometric Exoplanet Search at the AIU Jena
Targets
nearby stellar multiple systems (distance < 100 pc)
Telescope and Instruments
single 8 m apertures (VLT and SUBARU)
AO assisted NIR imager
NIR narrow band filter
Calibration
old globular cluster (47Tuc and M15)
Tristan Röll (AIU Jena)
Astrometric search for exoplanets
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Astrometric Exoplanet Search at the AIU Jena
Tristan Röll (AIU Jena)
Astrometric search for exoplanets
10 / 24
Astrometric Exoplanet Search at the AIU Jena
„Wobble“-Orbit
Tristan Röll (AIU Jena)
Astrometric search for exoplanets
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Astrometric Exoplanet Search at the AIU Jena
„Wobble“-Orbit
Tristan Röll (AIU Jena)
Astrometric search for exoplanets
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Astrometric Exoplanet Search at the AIU Jena
„Wobble“-Orbit
Tristan Röll (AIU Jena)
Astrometric search for exoplanets
13 / 24
First Target System: HD 19994 A&B
RV planet candidate HD 19994 Ab
Mayor et al. (2004)
Ppl ' 535 days
apl ' 1.4 AU
m sin i ' 1.7 MJup
Pbinary ≥ 1400 years
distance ' 22.6 pc
MA ' 1.34 M ,
Tristan Röll (AIU Jena)
MB ' 0.4 M
Astrometric search for exoplanets
14 / 24
First Target System: HD 19994 A&B
RV planet candidate HD 19994 Ab
Mayor et al. (2004)
Ppl ' 535 days
apl ' 1.4 AU
m sin i ' 1.7 MJup
Expected Astrometric Signal:
Pbinary ≥ 1400 years
Θ(i = 90◦ ) ' 150 µas
distance ' 22.6 pc
MA ' 1.34 M ,
Tristan Röll (AIU Jena)
MB ' 0.4 M
Θ(13 MJup ) ' 1.2 mas
Astrometric search for exoplanets
14 / 24
Residual [µas]
Deviation [mas]
Sep [pixel]
HD 19994 A&B - Astrometric measurements
HD19994 A & (BC) - Separation
177.0
176.5
176.0
175.5
175.0
174.5
174.0
173.5
173.0
54000
54200
54400
54600
54800
55000
55200
12
10
8
6
4
2
0
2
4
6
54000
54200
54400
54600
54800
55000
55200
200
150
100
50
0
50
100
150
200
54000
54200
54400
54600
54800
55000
55200
Tristan Röll (AIU Jena)
Time [MJD]
Astrometric search for exoplanets
Measurements
Binary
Wobble
15 / 24
HD 19994 B&C - Speckle Interferometry
HD19994 B & C - Separation
70
Sep [mas]
60
50
40
30
20
10
53500
54000
53500
54000
54500
55000
54500
55000
Residual [mas]
15
10
5
0
5
10
Time [MJD]
(speckle interferometry program written by Rainer Köhler)
Tristan Röll (AIU Jena)
Astrometric search for exoplanets
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Residual [m/s]
RV [km/s]
HD 19994 B&C - Radial Velocity (CRIRES, VLT)
50
45
40
35
30
25
20
15
10
5
HD19994 B & C - RV
54800
54900
55000
55100
55200
55300
B
C
BC
55400
55500
mcomp / M = 0.605
Ecc = 0.36
Inc [deg] = 108.63
P [days] = 378.1
atotal [AU] = 0.97
ω [deg] = 335.9
300
200
100
0
100
200
300
54800
54900
55000
55100
55200
Time [MJD]
55300
55400
55500
(radial velocity data by Andreas Seifahrt and Jacob Bean)
Tristan Röll (AIU Jena)
Astrometric search for exoplanets
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HD 19994 B - Wobble Orbit
P [days] = 378.07 +0.64
−0.60
mC [M ] = 0.326 ± 0.012
MB [M ] = 0.54 ± 0.014
Inc [deg] = 108.58 +0.54
−0.51
Ecc = 0.36 ± 0.014
d [pc] = 20.11 +0.30
−0.27
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Astrometric search for exoplanets
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HD 19994 B - Wobble Orbit
P [days] = 378.07 +0.64
−0.60
mC [M ] = 0.326 ± 0.012
MB [M ] = 0.54 ± 0.014
Inc [deg] = 108.58 +0.54
−0.51
Ecc = 0.36 ± 0.014
d [pc] = 20.11 +0.30
−0.27
HD 19994 is a triple system, harboring one exoplanet
Tristan Röll (AIU Jena)
Astrometric search for exoplanets
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Exoplanet Detection - Sensitivity
102
(minimum) mass [MJup]
101
Jupiter
100
Saturn
10-1
Θ(50 pc) = 1 mas
Θ(10 pc) = 100 µas
Θ(5 pc) = 1 µas
K = 10 m/s
K = 1 m/s
K = 10 cm/s
∆F / F ' 1 %
∆F / F ' 0.1 %
∆F / F ' 0.01 %
Neptune
10-2
10-3
10-2
1 day
23.8 %
13.8 ◦
1 week
6.5 %
3.7 ◦
10-1
1 month
2.5 %
1.4 ◦
Earth
1 year
0.5 %
0.3 ◦
100
10 years
0.1 %
0.1 ◦
semi-major axis [AU]
101
50 years
300 years
102
(data from exoplanet.eu)
Tristan Röll (AIU Jena)
Astrometric search for exoplanets
19 / 24
Earth’s Atmospheric Turbulence’s
(by Tyson: “Introduction to Adaptive Optics”)
Tristan Röll (AIU Jena)
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Filter Transmission Curves
1.2
1.0
0.8
0.6
ESO NB2.17 Filter
Filter-curve (Ks)
λeff [nm] = 2136.40
Normalized Flux and Transmission curve + constant
Normalized Flux and Transmission curve + constant
ESO Ks Filter
Teff [K] = 2000
λeff [nm] = 2123.49
Teff [K] = 20000
∆λeff [nm] = 12.91
0.4
0.2
0.01.7
1.8
1.9
2.0
2.1
λ [µm]
2.2
2.3
2.4
2.5
1.2
1.0
0.8
0.6
Filter-curve (NB2.17)
λeff [nm] = 2171.38
Teff [K] = 2000
λeff [nm] = 2171.32
Teff [K] = 20000
∆λeff [nm] = 0.06
0.4
0.2
0.0
2.13
2.14
2.15
2.16
λ [µm]
2.17
2.18
2.19
2.20
Extreme case: Two blackbodies with Teff = 2000 K and Teff = 20000 K
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Astrometric search for exoplanets
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Differential Chromatic Refraction
ESO Ks Filter
DCR [µas]
ESO NB2.17 Filter
DCR [µas]
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Astrometric search for exoplanets
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Residual [deg/1000]
Deviation [deg]
Angle [deg]
HD 19994 A&B - Astrometric measurements
205.0
204.5
204.0
203.5
203.0
202.5
202.0
201.5
201.0
HD19994 A & (BC) - Position Angle
Measurements
Binary
Wobble
54000
54200
54400
54600
54800
55000
55200
0.15
54000
54200
54400
54600
54800
55000
55200
2.5
2.0
1.5
1.0
0.5
0.0
0.5
1.0
1.5
2.0
54000
54200
54400
54600
54800
55000
55200
0.05
0.00
0.05
0.10
Tristan Röll (AIU Jena)
Time [MJD]
Astrometric search for exoplanets
23 / 24
PA [deg]
HD 19994 B&C - Speckle Interferometry
400
350
300
250
200
150
100
50
0
50
HD19994 B & C - Position Angle
53500
54000
53500
54000
54500
55000
54500
55000
Residual [deg]
100
50
0
50
100
150
Time [MJD]
(speckle interferometry program written by Rainer Köhler)
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Astrometric search for exoplanets
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