universidad de valencia spain · importat feature: fast rotator (0.5 days): broadening of the...
TRANSCRIPT
![Page 1: Universidad de Valencia Spain · Importat feature: FAST ROTATOR (0.5 days): Broadening of the spectral lines, limiting precision of Doppler techniques to 5km/s Present radio emission](https://reader033.vdocuments.us/reader033/viewer/2022060709/6075a9ee23481c0060291b53/html5/thumbnails/1.jpg)
Astrometric Detection of Extrasolar Planets
Jose C. GuiradoUniversidad de Valencia Spain
![Page 2: Universidad de Valencia Spain · Importat feature: FAST ROTATOR (0.5 days): Broadening of the spectral lines, limiting precision of Doppler techniques to 5km/s Present radio emission](https://reader033.vdocuments.us/reader033/viewer/2022060709/6075a9ee23481c0060291b53/html5/thumbnails/2.jpg)
Overview
Capabilities of astrometry Capabilities of radio astrometry - SKATechnique cooperation: the case for AB Dor
![Page 3: Universidad de Valencia Spain · Importat feature: FAST ROTATOR (0.5 days): Broadening of the spectral lines, limiting precision of Doppler techniques to 5km/s Present radio emission](https://reader033.vdocuments.us/reader033/viewer/2022060709/6075a9ee23481c0060291b53/html5/thumbnails/3.jpg)
Planet Detection Score
Radial velocity is a very efficient technique Astrometry is the technique of the past… …and the technique of the future
Radial Velocity Astrometry
120 2 ?
![Page 4: Universidad de Valencia Spain · Importat feature: FAST ROTATOR (0.5 days): Broadening of the spectral lines, limiting precision of Doppler techniques to 5km/s Present radio emission](https://reader033.vdocuments.us/reader033/viewer/2022060709/6075a9ee23481c0060291b53/html5/thumbnails/4.jpg)
AstrometryDetermination of 3D orbit. Unambiguous mass determination.(masses determined by Doppler techniques are coupled with orbit inclination)
Young and active stars may be studied Sensitivity to longer periods (larger a’s):
Expected very high-precision: – SIM (4µas) & GAIA (1µas)
da
Mm p
s
p=θ
![Page 5: Universidad de Valencia Spain · Importat feature: FAST ROTATOR (0.5 days): Broadening of the spectral lines, limiting precision of Doppler techniques to 5km/s Present radio emission](https://reader033.vdocuments.us/reader033/viewer/2022060709/6075a9ee23481c0060291b53/html5/thumbnails/5.jpg)
Mass vs. Separation
Radial speed
limit: 5
m/s
Wobble limit: 1mas
Wobble limit: 0.01mas
J. Liebert (2000)
![Page 6: Universidad de Valencia Spain · Importat feature: FAST ROTATOR (0.5 days): Broadening of the spectral lines, limiting precision of Doppler techniques to 5km/s Present radio emission](https://reader033.vdocuments.us/reader033/viewer/2022060709/6075a9ee23481c0060291b53/html5/thumbnails/6.jpg)
Radio AstrometryM. Perryman (2000)
SKA
![Page 7: Universidad de Valencia Spain · Importat feature: FAST ROTATOR (0.5 days): Broadening of the spectral lines, limiting precision of Doppler techniques to 5km/s Present radio emission](https://reader033.vdocuments.us/reader033/viewer/2022060709/6075a9ee23481c0060291b53/html5/thumbnails/7.jpg)
Radio Astrometry
Space-based expected (2010) very high-precision in the optical:
– SIM (4µas) & GAIA (1µas)
1983
~ 5 µas
![Page 8: Universidad de Valencia Spain · Importat feature: FAST ROTATOR (0.5 days): Broadening of the spectral lines, limiting precision of Doppler techniques to 5km/s Present radio emission](https://reader033.vdocuments.us/reader033/viewer/2022060709/6075a9ee23481c0060291b53/html5/thumbnails/8.jpg)
Radio Astrometry
Treuhaft & Lowe, AJ, 1991
Reid et al., ApJ, 1999
![Page 9: Universidad de Valencia Spain · Importat feature: FAST ROTATOR (0.5 days): Broadening of the spectral lines, limiting precision of Doppler techniques to 5km/s Present radio emission](https://reader033.vdocuments.us/reader033/viewer/2022060709/6075a9ee23481c0060291b53/html5/thumbnails/9.jpg)
The S5 Polar Cap sampleFlat spectrum radio sources: 8 QSOs 5 BL-Lac objects
Long-term astrometric program
λ= 3.6, 2, 0.7 cm
Bootstrapping techniques
Ros et al 2000Pérez-Torres et al 2004
![Page 10: Universidad de Valencia Spain · Importat feature: FAST ROTATOR (0.5 days): Broadening of the spectral lines, limiting precision of Doppler techniques to 5km/s Present radio emission](https://reader033.vdocuments.us/reader033/viewer/2022060709/6075a9ee23481c0060291b53/html5/thumbnails/10.jpg)
The technique
)(),( tt INSTRUMtropo τντ ++++= ))(,())(()()( tEtEtt IONSTRGEO νττττ
c
sDgeoτ
⋅=
ρ
INSTRUMres,B-A
res,TROPOB-A
IONres,B-A
STRres,B-A
res,GEOB-A
resB-A φφφφφφ ++++=
0 00
•Phase-delay astrometry
•Phase-reference mapping
![Page 11: Universidad de Valencia Spain · Importat feature: FAST ROTATOR (0.5 days): Broadening of the spectral lines, limiting precision of Doppler techniques to 5km/s Present radio emission](https://reader033.vdocuments.us/reader033/viewer/2022060709/6075a9ee23481c0060291b53/html5/thumbnails/11.jpg)
High resolution and astrometric precision
Theoretical precision for an interferometer:
Sources of error:– Φ-extrapolation– Differential contribution from atmosphere and
ionosphere– Structures of reference and target source
DSNRλ1
2π1σ δα, ××=
D λ σSNR>15 300 km 6cm 440 µas 3000km 6cm 44 µas 300km 1.3cm 90 µas
3000km 1.3cm 9 µas
![Page 12: Universidad de Valencia Spain · Importat feature: FAST ROTATOR (0.5 days): Broadening of the spectral lines, limiting precision of Doppler techniques to 5km/s Present radio emission](https://reader033.vdocuments.us/reader033/viewer/2022060709/6075a9ee23481c0060291b53/html5/thumbnails/12.jpg)
Sources of Error in Astrometry:Solutions for new instruments
Multi-beam System:– Φ-extrapolation problem solved – simultaneous
observation from target and reference– Different lines of sight: tomography of the
atmosphere/ionosphere - removal of propagation medium biases
On-the-fly mapping:– Removal of structure contribution of reference (and
target)
![Page 13: Universidad de Valencia Spain · Importat feature: FAST ROTATOR (0.5 days): Broadening of the spectral lines, limiting precision of Doppler techniques to 5km/s Present radio emission](https://reader033.vdocuments.us/reader033/viewer/2022060709/6075a9ee23481c0060291b53/html5/thumbnails/13.jpg)
Sensitivity
A.R. Taylor (2000)
![Page 14: Universidad de Valencia Spain · Importat feature: FAST ROTATOR (0.5 days): Broadening of the spectral lines, limiting precision of Doppler techniques to 5km/s Present radio emission](https://reader033.vdocuments.us/reader033/viewer/2022060709/6075a9ee23481c0060291b53/html5/thumbnails/14.jpg)
SKA: Sensitivity and High Resolution
Baselines of thousands of kilometers will match the progress in sensitivity with the present VLBI resolution
Sensitivities expected: far below µJy/beam
The Φ-referencing increases the integration time from minutes to hours detection of weaker sources
![Page 15: Universidad de Valencia Spain · Importat feature: FAST ROTATOR (0.5 days): Broadening of the spectral lines, limiting precision of Doppler techniques to 5km/s Present radio emission](https://reader033.vdocuments.us/reader033/viewer/2022060709/6075a9ee23481c0060291b53/html5/thumbnails/15.jpg)
Search for Planets and Star Companions: VLBI Program
Antennas at Effelsberg/Robledo/ GoldstoneSingle baseline: ~1 mas astrometric resolutionSearch for companions in – stars nearby the sun (10pc) – small mass– single (or wide separation binaries)– with (some) radio emission
dMe stars look the most suitable targets
![Page 16: Universidad de Valencia Spain · Importat feature: FAST ROTATOR (0.5 days): Broadening of the spectral lines, limiting precision of Doppler techniques to 5km/s Present radio emission](https://reader033.vdocuments.us/reader033/viewer/2022060709/6075a9ee23481c0060291b53/html5/thumbnails/16.jpg)
Search for Planets and Star Companions: VLBI Program
dMe stars look the most suitable targets
![Page 17: Universidad de Valencia Spain · Importat feature: FAST ROTATOR (0.5 days): Broadening of the spectral lines, limiting precision of Doppler techniques to 5km/s Present radio emission](https://reader033.vdocuments.us/reader033/viewer/2022060709/6075a9ee23481c0060291b53/html5/thumbnails/17.jpg)
Search for Planets and Star Companions: VLBI Program
dMe stars look the most suitable targets
![Page 18: Universidad de Valencia Spain · Importat feature: FAST ROTATOR (0.5 days): Broadening of the spectral lines, limiting precision of Doppler techniques to 5km/s Present radio emission](https://reader033.vdocuments.us/reader033/viewer/2022060709/6075a9ee23481c0060291b53/html5/thumbnails/18.jpg)
![Page 19: Universidad de Valencia Spain · Importat feature: FAST ROTATOR (0.5 days): Broadening of the spectral lines, limiting precision of Doppler techniques to 5km/s Present radio emission](https://reader033.vdocuments.us/reader033/viewer/2022060709/6075a9ee23481c0060291b53/html5/thumbnails/19.jpg)
Technique cooperation: the case of AB Dor
Very well known southern-hemisphere PMS star (mv = 6.9)Importat feature: FAST ROTATOR (0.5 days):
Broadening of the spectral lines, limiting precision of Doppler techniques to 5km/sPresent radio emission via dynamo effect
![Page 20: Universidad de Valencia Spain · Importat feature: FAST ROTATOR (0.5 days): Broadening of the spectral lines, limiting precision of Doppler techniques to 5km/s Present radio emission](https://reader033.vdocuments.us/reader033/viewer/2022060709/6075a9ee23481c0060291b53/html5/thumbnails/20.jpg)
Technique cooperation: the case of AB Dor
Very well known southern-hemisphere PMS star (mv = 6.9)Importat feature: FAST ROTATOR (0.5 days):
Broadening of the spectral lines, limiting precision of Doppler techniques to 5km/sPresent radio emission via dynamo effect
0.76 M
0.08-0.11 M
Guirado et al. (1997, ApJ, 490, 835)
![Page 21: Universidad de Valencia Spain · Importat feature: FAST ROTATOR (0.5 days): Broadening of the spectral lines, limiting precision of Doppler techniques to 5km/s Present radio emission](https://reader033.vdocuments.us/reader033/viewer/2022060709/6075a9ee23481c0060291b53/html5/thumbnails/21.jpg)
Hipparcos data
VLBI data
Orbit DeterminationWeighted-least-squares fit of the VLBI+HIPPARCOS positions to estimate simultaneously
5 astrometric parameters
7 orbital parameters (Thieles-Innes method)
Mass estimate (ABDor C): 0.08 – 0.11 M
![Page 22: Universidad de Valencia Spain · Importat feature: FAST ROTATOR (0.5 days): Broadening of the spectral lines, limiting precision of Doppler techniques to 5km/s Present radio emission](https://reader033.vdocuments.us/reader033/viewer/2022060709/6075a9ee23481c0060291b53/html5/thumbnails/22.jpg)
![Page 23: Universidad de Valencia Spain · Importat feature: FAST ROTATOR (0.5 days): Broadening of the spectral lines, limiting precision of Doppler techniques to 5km/s Present radio emission](https://reader033.vdocuments.us/reader033/viewer/2022060709/6075a9ee23481c0060291b53/html5/thumbnails/23.jpg)
ABDor
ABDor CABDor
ABDor
ABDor C
![Page 24: Universidad de Valencia Spain · Importat feature: FAST ROTATOR (0.5 days): Broadening of the spectral lines, limiting precision of Doppler techniques to 5km/s Present radio emission](https://reader033.vdocuments.us/reader033/viewer/2022060709/6075a9ee23481c0060291b53/html5/thumbnails/24.jpg)
Hipparcos data
VLBI data
Imaging
(New) Orbit Determination
Mass estimate (ABDor C): 0.08 – 0.11 M
Mass estimate (three techniques): 0.084 +/- 0.004 M
Even a modest detection of the position of ABDorC would lead to very precise determination of its mass.
![Page 25: Universidad de Valencia Spain · Importat feature: FAST ROTATOR (0.5 days): Broadening of the spectral lines, limiting precision of Doppler techniques to 5km/s Present radio emission](https://reader033.vdocuments.us/reader033/viewer/2022060709/6075a9ee23481c0060291b53/html5/thumbnails/25.jpg)
Summary
The SKA will increase the observed radio stars from hundreds to millions of objectsSKA in astrometric mode:– Link with the optical astrometric satellites (SIM, GAIA)– Discovery of low-mass objects and exoplanets
High resolution is needed to reach the highest astrometricprecisionCooperation with other techniques is needed to confirm or improve the detections.