The Carnegie Astrometric Planet Search and the role of ground based astrometry in the pre-Gaia era.
Guillem Anglada-Escude (1,2)Alan P. Boss(1)
Alycia Weinberger (1)Ian Thompson (1)
(1)Carnegie Institution for Science(2) Institute for Astrophysics - University of Goettingen
Astrometry and radial velocity methods
K
Time
RV
a
1º
3474 km
1’
120 km
1/60
1/60
1’’
2 km
1/1000
2 m
1 mas
2 cm
10 mas1/100
1 mas
A closer look at astrometry…
Astrometric recipes
masMM
dR
mm sun
pc
AU
jup
p *
a
Exo-Jupiter formula
3*M
MdR
mm
as sun
pc
AU
Earth
pma
Exo-Earth formula
G dwarf @ 10 pc
M dwarf @ 10 pc
0.1 mas 1.0 masMan on
the moonBook on
the moon
3 mas0.3 masPaper
width on the moon
Euro width on the moon
Gaia/ESA Ground based
Ground based AstrometryWhy M dwarfs?
Numerous
Faint
Low mass
Poorly characterized
Hosts to habitable planets (that can be
detected)
Alan Boss (PI, DTM/CIW)Alycia Weinberger (DTM/CIW)Ian Thompson (OCIW)Chistoph Brik (OCIW)Greg Burley (OCIW)
2.5m duPont Telescope. Las Campanas Observatory, Chile
Follow-up a sample of 120 M, L and T dwarfs
Carnegie Astrometric planet Search
Carnegie Astrometric planet Search
CAPScam (I band), 2048x2048
Classic local astrometry
Input catalog Extract, centroid and crossmatch the sources
Fit field distortions Shift (2 par)rotation, scale (4 par)Quadratic deformations (6 para)
Obtain a new catalog
Iterate
CAPS pipeline : ATPa software
If you are interested in testing with your own images, please check http://www.dtm.ciw.edu/anglada/
•Fully coded in Java (run on your computer)
•Graphic User Interface
•One night processing and Astrometric Iterative solution
• Final Data products : catalog, maps of extracted sources, reference stars, motion of each star, etc.
It also has a Manual!
Carnegie Astrometric Planet search : Lots of parallaxes of cool dwarfs
200+ new and updated parallaxes
Carnegie Astrometric Planet Search program so far…
• Astrometric detection needs long time baselines (5-10 yr)
• Overall precision better than 1 mas/epoch.
• Almost 4 years of baseline, Gas giants should be detected soon (if present)
• About 120 M dwarfs
Carnegie Astrometric Planet Search… candidates?
brown dwarfs
gas giant planets
0.25 milliarcsec accuracy, S/N = 4
0.1HZ
0.5 HZ
GJ 317 GJ 1214VB 10
Astrometric detectionPravdo & Shaklan 2010 ApJ
P=270 daysM ~ 6 Mjup
D = 7 pcGalactic plane
Doppler candidateJohnson et al 2007, ApJ
P=690 daysM sin i ~ 2 Mjup
D = 9.6 pc[Fe/H] = -0.3??
Transit + Doppler planetCharbonneau et al. 2009, Nat
P=1.83 daysM sin i ~ 6 Meartj
D = 12.0 pcRadius 15% larger??
Lessons learned from individual targets
? ? ?
Lessons learned from individual targets : VB 10
Black & Scargle 1982
Astrometry2 x offsets 2 x Proper motions 1 x Parallax
HD 125612Fischer et al. 2007
Doppler1xoffset
GJ 317, Anglada-Escude et al. 2012
Lessons learned from individual targets : VB 10
Pravdo & Shaklan ApJ, 2009
Residual periodograms
Astrometric periodograms
K = 1500 m/sK = 3000 m/s
Anglada-Escude et al. ApJ, 2011
Anglada-Escude et al. ApJ 2011, RV follow-up with MIKE/MagellanBean et al. 2011, RV follow-up with CRIRES/VLT
Lazorenko et al. 2011, Astrometric follow-up
Lessons learned from individual targets : VB 10
49.9 days 270 days
Lessons learned from individual targets
GJ 317 GJ 1214VB 10
Astrometric detectionPravdo & Shaklan 2010 ApJ
P=270 daysM ~ 6 Mjup
D = 7 pcGalactic plane
Doppler candidateJohnson et al 2007, ApJ
P=690 daysM sin i ~ 2 Mjup
D = 9.6 pc[Fe/H] = -0.3??
Transit + Doppler planetCharbonneau et al. 2009, Nat
P=1.83 daysM sin i ~ 6 Meartj
D = 12.0 pcRadius 15% larger??
Astrometric periodograms
(need better understanding of sampling)
d = 9.6 pcM* = 0.24 Msun
M sin i = 1.85 Mjup
P = 692 days, a = 0.95 AU
masMM
dR
mm
sun
pc
AU
jup
p *
a
Exo-Jupiter formula
0.78 mas
Jonhson, Butler et al. ApJ 2007
Lessons learned from individual targets : GJ 317
d = 14.9 pc0.32 mas M* = 0.42 Msun
M sin i = 1.8 Mjup
P = 692 days a = 0.95 AU
d = 9.6 pca =0.78 mas
Lessons learned from individual targets : GJ 317
𝒗 𝒓 (𝒕 )=𝜸+𝑲 ¿𝑿 (𝒕 )=𝑿𝟎+𝝁𝜶 (𝒕− 𝒕𝟎 )+∆𝜶 (𝒕)−𝝅 𝒙𝒐𝒃𝒔 ∙ �̂�𝜶𝑨𝑼
𝒀 (𝒕 )=𝒀 𝟎+𝝁𝜹 (𝒕− 𝒕𝟎 )+∆𝜹 (𝒕 )−𝝅 𝒙𝒐𝒃𝒔 ∙ �̂�𝜹𝑨𝑼
Lessons learned from individual targets : GJ 317
𝐿∝𝐸𝑋𝑃 [− 12𝜒2]
Likelihood function
Period
Mas
sLessons learned from individual targets : GJ 317
𝐿∝𝐸𝑋𝑃 [− 12𝜒2]
Likelihood function
Period
Mas
s
Provides optimal sampling in highly dimensional spaces
N = 13
Run a few million steps and you are done!
Lessons learned from individual targets : GJ 317
Lessons learned from individual targets : GJ 317
First exoplanet “confirmed” with Ground based astrometry!
Lessons learned from individual targets : GJ 317
Lessons learned from individual targets
GJ 317 GJ 1214
Doppler candidateJohnson et al 2007, ApJ
P=690 daysM sin i ~ 2 Mjup
D = 9.6 pc[Fe/H] = -0.3??
Transit + Doppler planetCharbonneau et al. 2009, Nat
P=1.83 daysM sin i ~ 6 Meartj
D = 12.0 pcRadius 15% larger??
VB 10
Astrometric detectionPravdo & Shaklan 2010 ApJ
P=270 daysM ~ 6 Mjup
D = 7 pcGalactic plane
Astrometric periodograms
(need better understanding of sampling)
Lessons learned from individual targets
GJ 317 GJ 1214VB 10
Astrometric detectionPravdo & Shaklan 2010 ApJ
P=270 daysM ~ 6 Mjup
D = 7 pcGalactic plane
Doppler candidateJohnson et al 2007, ApJ
P=690 daysM sin i ~ 2 Mjup
D = 9.6 pc[Fe/H] = -0.3??
Transit + Doppler planetCharbonneau et al. 2009, Nat
P=1.83 daysM sin i ~ 6 Meartj
D = 12.0 pcRadius 15% larger??
Combine RV+Astrometry
Astrometric periodograms
(need better understanding of sampling)
Lessons learned from individual targets : GJ 1214
CAPS Astrometry (new)RMS < 1.0 mas
HARPS-TERRA RVs (updated)
30 transit times and updated
Transit observablesSada et al, 2010, Carter et al. 2011, Kundurthy et al., 2011
• K band, low res(new)• 4 Optical bands• 3x2MASS bands• 4xWISE bands (new)
Lessons learned from individual targets : GJ 1214
d
M*
L*
Teff
14.47 (0.14) pc
0.175 (0.009) Ms
3.9 10-3 Ls
3200 K
12.9 (1.0) pc
0.155 Ms
3.3 10-3Ls
2900 K
+12%+13%
+19%+10%
Previous NEW!
Lessons learned from individual targets : GJ 1214
Lessons learned from individual targets : GJ 1214
Lessons learned from individual targets
GJ 317 GJ 1214VB 10
Astrometric detectionPravdo & Shaklan 2010 ApJ
P=270 daysM ~ 6 Mjup
D = 7 pcGalactic plane
Doppler candidateJohnson et al 2007, ApJ
P=690 daysM sin i ~ 2 Mjup
D = 9.6 pc[Fe/H] = -0.3??
Transit + Doppler planetCharbonneau et al. 2009, Nat
P=1.83 daysM sin i ~ 6 Meartj
D = 12.0 pcRadius 15% larger??
Combine RV+Astrometry
Astrometric periodograms
(need better understanding of sampling)
Lessons learned from individual targets
GJ 317 GJ 1214VB 10
Astrometric detectionPravdo & Shaklan 2010 ApJ
P=270 daysM ~ 6 Mjup
D = 7 pcGalactic plane
Doppler candidateJohnson et al 2007, ApJ
P=690 daysM sin i ~ 2 Mjup
D = 9.6 pc[Fe/H] = -0.3??
Transit + Doppler planetCharbonneau et al. 2009, Nat
P=1.85 daysM sin i ~ 6 Meartj
D = 14.5 pcEverything is good!
Combine RV+Astrometry
Transits+RV, astrometry
Simultaneous FIT!
Astrometric periodograms
(need better understanding of sampling)
‘Other’ exoplanet related programs… 10 years before Gaia
Young field M dwarfs (UV and X ray sources) from Shkolnik et al. 2009 ApJ
12 New members to nearby young moving groups (Beta Pictoris 10 Myr, AB Dor 40 Myr)
61 new parallaxes!
Shkonlik, Anglada-Escude, Weinberger, Boss et al. 2011 (to be submitted!)
Based on astrometry obtained with ATPa (just accepted for publication, ApJ)
J. O’Faherty PhD. Thesis
Early L brown dwarf at 12 pc
Early L brown dwarf at 12 pc
Synergies?
The obvious…
• Combine with ground based observations
• Targeted follow-up of peculiar systems
• Extend time baselines
How you do that???
𝒗 𝑯𝑰𝑹𝑬𝑺(𝒕 )=𝜸𝟏+𝑲 ¿
𝒗 𝑯𝑨𝑹𝑷𝑺(𝒕 )=𝜸𝟐+𝑲 ¿
𝒖 (𝒕 )=𝒖𝟎+𝝁 ′𝜶 (𝒕−𝒕𝟎 )−𝝅𝒙𝒐𝒃𝒔 ∙ �̂�𝜶𝑨𝑼 +∆𝜶(𝒕)
v
𝒓=¿(�⃗�−�⃗�𝟎) �⃗�>¿
Gaia
𝑿 (𝒕 )=𝑿𝟎+𝝁𝜶 (𝒕−𝒕𝟎)−𝝅�⃗�𝒐𝒃𝒔 ∙ �̂�𝜶𝑨𝑼 +∆𝜶 (𝒕)
𝒀 (𝒕)=𝒀 𝟎+𝝁𝜹 (𝒕− 𝒕𝟎 )−𝝅𝒙𝒐𝒃𝒔 ∙ �̂�𝜹𝑨𝑼 +∆𝜹 (𝒕 )
CAPS
DopplerM
CMC
How you do that???
𝒗 𝑯𝑰𝑹𝑬𝑺(𝒕 )=𝜸𝟏+𝑲 ¿
𝒗 𝑯𝑨𝑹𝑷𝑺(𝒕 )=𝜸𝟐+𝑲 ¿
𝒖 (𝒕 )=𝒖𝟎+𝝁 ′𝜶 (𝒕−𝒕𝟎 )−𝝅𝒙𝒐𝒃𝒔 ∙ �̂�𝜶𝑨𝑼 +∆𝜶(𝒕)
v
𝒓=¿(�⃗�−�⃗�𝟎) �⃗�>¿
Gaia
𝑿 (𝒕 )=𝑿𝟎+𝝁𝜶 (𝒕−𝒕𝟎)−𝝅�⃗�𝒐𝒃𝒔 ∙ �̂�𝜶𝑨𝑼 +∆𝜶 (𝒕)
𝒀 (𝒕)=𝒀 𝟎+𝝁𝜹 (𝒕− 𝒕𝟎 )−𝝅𝒙𝒐𝒃𝒔 ∙ �̂�𝜹𝑨𝑼 +∆𝜹 (𝒕 )
CAPS
DopplerM
CMC
𝑿 (𝒕 )=𝑿𝟎+𝝁𝜶 (𝒕−𝒕𝟎)−𝝅𝒑 (𝒕 )+𝑨𝒄𝒐𝒔 (𝒘𝒕 )+𝑩𝒔𝒊𝒏 (𝒘𝒕 )
𝒀 (𝒕 )=𝒀 𝟎+𝝁𝜹 (𝒕− 𝒕𝟎 )−𝝅𝒒(𝒕 )+𝑪𝒄𝒐𝒔 (𝒘𝒕 )+𝑫𝒔𝒊𝒏(𝒘𝒕 )
Astrometric model is LINEAR in the relevant quantities
Only becomes (a bit) more complicate when combined with RVs, or for highly eccentric orbits (e>0.6)
Conclusions
Experience : As ground based transit surveys did for COROT & Kepler… prepares the tools, identifies pitfalls
Cool parallaxes NOW : Ground based astrometry, gives your parallaxes NOW at sufficient accuracy (nearby cool stars)
When Gaia data is released (residuals, not solutions!) …
• Combine astrometric solutions• Time to pack (at least CAPS, RECONS and a few others)• … work continues on L, T and Y dwarfs! (nIR astrometry)
First population statistics of ‘long period’ Gas giants around M dwarfs available before Gaia
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