RIPL Radio Interferometric Planet Search
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Transcript of RIPL Radio Interferometric Planet Search
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RIPLRIPLRadio Radio
Interferometric Interferometric Planet SearchPlanet Search
Geoffrey BowerGeoffrey Bower
UC BerkeleyUC BerkeleyCollaborators: Alberto Bolatto (UMD), Eric Ford (UFL),
Paul Kalas, Anna Treaster, Vince Viscomi (UCB)
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MM Wavelength T Tauri MM Wavelength T Tauri Outburst in OrionOutburst in Orion
22ndnd most luminous stellar radio most luminous stellar radio outburstoutburst
Briefly, brightest object in Briefly, brightest object in nebulanebula
Required long baselines for Required long baselines for detectiondetection
Magnetized T Tauri outburstMagnetized T Tauri outburst Contemporaneous with X-ray Contemporaneous with X-ray
outburstoutburst Many such objects likely to be Many such objects likely to be
found by CARMA & ALMAfound by CARMA & ALMA
BIMA A configuration images(Bower, Plambeck, Bolatto, Graham, de Pater, McCrady, Baganoff 2004)
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Orion Nebula ParallaxOrion Nebula Parallaxw/Star GMR-Aw/Star GMR-A
D=389 pc +/- 5%<0.1 mas/epochSandstrom, Peek, Bower, Bolatto,Plambeck 2007Astro-ph/0706.2361
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Planets are Easy to Planets are Easy to DetectDetect
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Companion to GJ 752B Companion to GJ 752B Detected w/Optical Detected w/Optical
AstrometryAstrometryPravdo & Shaklan 2009
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White et al
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Gudel 2002
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Requirements of a Planet Requirements of a Planet SurveySurvey
Low mass, nearby starLow mass, nearby star Astrometric displacement ~ 1 masAstrometric displacement ~ 1 mas
Nonthermal radio emissionNonthermal radio emission S ~ 1 mJyS ~ 1 mJy F ~ GHzF ~ GHz Positional stability < 0.1 masPositional stability < 0.1 mas
Stable ImageStable Image Active, but not too activeActive, but not too active
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VLA M dwarf Flux SurveyVLA M dwarf Flux Survey 174 X-ray selected 174 X-ray selected
nearby M dwarfsnearby M dwarfs 10 minute VLA 10 minute VLA
observations with 50 observations with 50 microJy rmsmicroJy rms
40 detections of 29 40 detections of 29 starsstars
Rough agreement X-Rough agreement X-ray-radio correlationray-radio correlation
No distinction between No distinction between early and late typesearly and late types
Bower, Bolatto, Ford, Kalas 2009, ApJ, in press
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Stars are VariableStars are Variable
EV LacOsten et al 2005
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Pilot SurveyPilot Survey
7 stars7 stars 3 epochs3 epochs < 10 days< 10 days
Hipparcos errors ~ Hipparcos errors ~ 1 mas/y1 mas/y
Error over 10 days Error over 10 days < 0.1 mas< 0.1 mas
TestTest DetectabilityDetectability Image stabilityImage stability
8000 km baselines3 cm wavelength1 mas resolutionAstrometry ~ beam/SNR
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Results from Pilot Study:Results from Pilot Study:Apparent Motion of GJ 4247Apparent Motion of GJ 4247
23 March 200625 March 200626 March 2006
15 mas
Comparison of radio positions (points) with predictions from Hipparcos astrometry (solid line) reveal noise-limited rms residuals ~0.1 milliarcseconds, approximately 1 stellar diameter.
Bower, Bolatto, Ford, Kalas 2009, ApJ, in press
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Pilot Study ResultsPilot Study Results
Residuals are sensitivity limited~0.2 mas
GJ 4247
GJ 896A
GJ 65B
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VPAS ResultsVPAS Results
GJGJ DetectionsDetections Proper MotionProper Motion
65B65B 3/33/3 Different from OpticalDifferent from Optical
285285 2/32/3 Optical, sensitivity Optical, sensitivity limitedlimited
896A896A 3/33/3 Optical, sensitivity Optical, sensitivity limitedlimited
42474247 3/33/3 Optical, sensitivity Optical, sensitivity limitedlimited
412B412B 0/30/3 --------------------
803803 1/21/2 --------------------
12241224 0/30/3 --------------------
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Results from Pilot Study:Results from Pilot Study:Constraints on Companion Constraints on Companion
MassesMasses Agreement with Agreement with
optical astrometry optical astrometry sets upper limit on sets upper limit on acceleration and acceleration and therefore companion therefore companion massesmasses MMpp < 3 – 10 M < 3 – 10 MJupJup @ 1 @ 1
AUAU Sensitivity is limited Sensitivity is limited
by the short lever arm by the short lever arm of VLBA observations: of VLBA observations: ~10 days~10 days
RIPL will extend this RIPL will extend this lever arm by factor of lever arm by factor of 100100 Semi-major Axis (AU)
Pla
net
Mass
(M
jup)
Bower, Bolatto, Ford, Kalas 2009, ApJ, in press
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RIPLRIPLRadio Interferometric Radio Interferometric
Planet SearchPlanet Search 30 stars30 stars 12 epochs/4 years12 epochs/4 years VLBA + GBTVLBA + GBT 512 Mb/s512 Mb/s 2 hours on source + 2 hours on source +
2 hours calibration2 hours calibration 25 microJy rms25 microJy rms
4 x lower than pilot 4 x lower than pilot surveysurvey
1392 hours total1392 hours total
Key question: What is fraction of long-period planets around low mass stars?
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RIPL SampleRIPL Sample
30 Stars30 Stars M1 – M8M1 – M8 V = 9.6 – 15.8 magV = 9.6 – 15.8 mag S_6cm = 0.1 – 6 mJyS_6cm = 0.1 – 6 mJy D = 2.7 – 9.5 pcD = 2.7 – 9.5 pc 11 are members of known binary or 11 are members of known binary or
multiple systemsmultiple systems
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Simulated RIPL ResultsSimulated RIPL Results
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RIPL SensitivityRIPL Sensitivity
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Current StatusCurrent Status Observing began Oct Observing began Oct
20072007 Approximately 4 Approximately 4
observations/monthobservations/month Expected completion in Expected completion in
mid-2011mid-2011 40% complete40% complete Pipeline processing Pipeline processing
underway (see poster by underway (see poster by Vince Viscomi)Vince Viscomi)
All stars detectedAll stars detected 60% of stars detected 60% of stars detected
in every epochin every epoch
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Benefits of Astrometric Benefits of Astrometric DetectionDetection
Unique methodUnique method Breaks degeneracy of RV searches for mass, Breaks degeneracy of RV searches for mass,
inclination angle, and ascending nodeinclination angle, and ascending node Probes low mass, active stars that are difficult Probes low mass, active stars that are difficult
to study with RV methodto study with RV method Planet fraction of low mass stars poorly Planet fraction of low mass stars poorly
determineddetermined Detects planets that can be studied with Detects planets that can be studied with
extreme AOextreme AO Ties radio and optical astrometric reference Ties radio and optical astrometric reference
frameframe
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RV Search ResultsRV Search ResultsFew M dwarf HostsFew M dwarf Hosts
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RV Search ResultsRV Search ResultsMost Planets are >10 pc Most Planets are >10 pc
DistantDistant
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RV Search ResultsRV Search ResultsWhat is Mplanet/Mstar?What is Mplanet/Mstar?
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Microlensing Search Microlensing Search ResultsResults
What is Mplanet/Mstar? What is Mplanet/Mstar?
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Microlensing Search Microlensing Search ResultsResults
Planets are Very DistantPlanets are Very Distant
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Comparative Sensitivity of Comparative Sensitivity of SearchesSearches
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Future Directions for Radio Future Directions for Radio Astrometry & PlanetsAstrometry & Planets
Bandwidth upgrade Bandwidth upgrade for VLBAfor VLBA 512 Mb/s 512 Mb/s 8 Gb/s 8 Gb/s 4 x sensitivity4 x sensitivity Calibrator density Calibrator density
increases by 8 xincreases by 8 x In-beam calibrators In-beam calibrators 10 microarcsec 10 microarcsec
accuracy accuracy Neptune Neptune mass planetsmass planets
Square Kilometer Square Kilometer ArrayArray 100 x sensitivity100 x sensitivity 3000-5000 km baselines3000-5000 km baselines 1 microarcsec accuracy 1 microarcsec accuracy
Earth mass Earth mass sensitivitysensitivity
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SummarySummary
Radio astrometry is sensitive to sub-Radio astrometry is sensitive to sub-Jupiter mass planets around M Jupiter mass planets around M dwarfsdwarfs
We can already exclude BD We can already exclude BD companions to three stars based on companions to three stars based on only three measurementsonly three measurements
RIPL survey will probe low mass, RIPL survey will probe low mass, active star parameter spaceactive star parameter space