Directly-Imaged Planets

Directly Imaging and Characterizing
Extrasolar Planets at High Contrast
Thayne Currie (U. Toronto, NAOJ Aug 2014!)
Adam Burrows (Princeton), Nikku Madhusudhan (Cambridge),
Ryan Cloutier (U. Toronto) + SEEDS Collaboration
Extrasolar Planets
Charbonneau et al. (2000)
MANY Extrasolar Planets
(Oakley & Cash 2009; Kaltenegger et al. 2007)
Direct Imaging
1. Challenges:
How to overcome them?
2. What we have learned
so far?
(e.g. atmospheres)
3. The Near Future?
Adaptive Optics 
Sharper Images, Helps Us
Separate Planet Light from Starlight
(C. Beichman, A. Tanner; Palomar PALM-3K)
Why Directly Imaging Planets is Hard
HR 8799 (Keck/NIRC2 H band; July 2005, Currie et al. 2012a)
Observing Techniques for Imaging Planets:
“Angular Differential Imaging” (ADI)
Post-Processing Techniques for Imaging Planets:
A-LOCI (T. Currie 2012, 2013, 2014)
Science Image
weights Ref.”Image”
A weighted, ‘locally
optimized combination of
(reference) images’ (LOCI)
(Lafreniere et al. 2007)
Detecting Planets with A-LOCI
Increased planet throughput, more
reliable photometry, (sometimes)
slight increase in SNR
Detecting Planets with A-LOCI
(T. Currie 2012,2013, 2014)
``Speckle filtering”
Truncate elements in
covariance matrix during
matrix inversion (similar to
truncation on # principle
components in PCA)
Exoplanet Direct Imaging with ADI and A-LOCI (ex. HR 8799)
Currie et al. (2012a)
Keck/NIRC2 (near-IR),
July 2005
(May 2012)
Exoplanet Direct Imaging with ADI and A-LOCI (ex. HR 8799)
Keck/NIRC2 (mid IR), November 2012
(Currie et al. 2014, in prep.)
Subaru/IRCS (mid-IR),
July 2012
VLT/NaCo (near-IR),
October 2010
Directly Imaged Planetary Systems
HR 8799 bcde
(Marois et
al. 2008, 2010; Kalas et al. 2008; Lagrange et al. 2010;
Currie et al. 2014a,b; Rameau et al. 2013; Kuzuhara et al. 2013)
Unpublished …
T. Currie, et al. in
Many candidates to reimage!
Current Limits on Imaging Planets:
Young super-jovian planets at > 10 AU
(Skemer et al. 2014; Currie et al. 2014 in prep)
Architectures of Directly-Imaged Planetary Systems
A “Scaled-Up” Version of the Solar System?
HR 8799 – hotter, more massive and brighter than the Sun
(Marois et al. 2010)
Orbits of Directly-Imaged Planets
(Nov. 2009 to Nov. 2012)
(Marois et al. 2010; Currie et al. 2012, 2014 in prep.; Mede, Currie et al. 2014 in prep.)
Atmospheres of Directly-Imaged Planets
(Currie et al. 2011a, 2014abc)
HR 8799 bcde
ROXs 42Bb
Directly-Imaged Planets:
Should Look like Field Brown Dwarfs?
Brown Dwarf Atmosphere Models: similar range
in Teff  young gas giant planet atmospheres?
(Burrows et al. 2006)
Near-Infrared Colors of Young Directly-Imaged
Currie et al. (2011a, 2013, 2014)
Fitting HR 8799b and c Data with Standard
Atmosphere Models Used for Brown Dwarfs
Currie et al. (2011a)
Thicker clouds for Planets (not in Field Brown Dwarfs)
= Huge difference
From Atmosphere Models in Currie et al. (2011a)
Young Gas Giants have Thick (Patchy?) Clouds
HR 8799c
HR 8799bcd(e?) – ~ 5—7 Mj, Teff ~800-1100 K, log(g) ~ 3.8-4.3
Currie et al. (2011a); Madhusudhan, Burrows, and Currie (2011)
Spectra of Directly-Imaged Planets
ROXs 42Bb (Currie et al. 2014a,b)
Spectra of Directly-Imaged Planets
H2 Index (2.17-2.24 micron flux ratio)  surface gravity tracer
Low surface gravity  thick clouds?
(Currie et al. 2014a,b; Currie et al. 2011a, 2013)
Direct Imaging in the Near Future:
SCExAO Project (2014-)
1. Extreme AO imager for Subaru
(PI O. Guyon).
Strehl Ratio (1.6 mic) ~ 90%
2. Undergoing on-sky
testing/engineering runs;
full power ~ late 2014?
IFU spectrograph
3. Exoplanet Imaging
as follow-on to SEEDS
What Can SCExAO Do?
15 Myr old;
30 pc away
SCExAO vs. First-Light TMT
SCExAO: Likely best exoplanet imager in North
until 2nd gen TMT (~2030)
NFIRAOS estimates from Marois et al. 2012
1. Challenges:
How to overcome them?
2. What we have learned
so far?
(e.g. atmospheres)
3. The Near Future?
Guyon (2013); Matsuo et al. (2013)
SCExAO: A Precursor to TMT Exoplanet Imaging
PIAA Coronagraph – planet imaging at ~ lambda/D
“Speckle Nulling”
Martinache & Guyon 2011; Jovanovic et al. 2013; Martinache et al. 2014
Matsuo et al. (2013)

similar documents