Spitzer Observations of Extrasolar Planets Joseph Harrington University of Central Florida Credit:...
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Transcript of Spitzer Observations of Extrasolar Planets Joseph Harrington University of Central Florida Credit:...
Spitzer Observationsof Extrasolar Planets
Joseph HarringtonUniversity of Central Florida
Cre
dit:
NA
SA /
JPL-
Cal
tech
/ R
. Hur
t (SS
C-C
alte
ch)
● Search for Life?
●Astronomers have been selling life for 400 years! $trong public motivator New phase space for planetary science
Interior composition & dynamicsAtmospheric chemistry (Fe, enstatite clouds)Atmospheric radiative chemodynamics!Orbital dynamics, habitability, formation
Why Study Extrasolar Planets?
© 1997 Warner Bros.
Challenge: Direct Observation
Do the Numbers(R/a)2 is usually very small!
Options: A: Increase t B: Reduce a or increase R by choice of planet C: Increase L or reduce d by choice of star D: Do something smarter than comparing reflected light
Correct answer: E: All of the above!
Trick: Transits!
Brown et al. (2001)
Get i, M, R
Trick: Secondary Eclipses!
Trick: Secondary Eclipses!
Contrast Models
Fortney et al. (2006)
First Measured Photons IDeming, Seager, Richardson, Harrington
Nature 434, 740-743 (2005)
HD 209458 b
Spitzer MIPS, 24 µm,1282 mid-IR array
1696 good images over 6 hours
10-sec exposures
1.5 h pre-eclipse, 3 h eclipse, 1.5 h post-eclipse
Data
Deming et al. (2005b)
HD 209458 b Results
F24 m = 55 ± 10 µJy
FP/F* = 0.0026 ± 0.00046
TB,24 m = 1130 ± 150 K
tSE = t=0 + P/2 ± 7 min
Significant orbital eccentricity very unlikelyInflated radius not likely due to another planet Primary eclipses consistent w/ optical result
(Richardson et al. 2006, ApJ)
First Measured Photons II!Charbonneau et al. submitted TrES-1 the same day!
2 wavelengths (4.5 and 8 µm) simultaneously
IRAC rather than MIPS, aperture photometry
FP/F*: 4.5 µm: 0.00066 ± 0.00013, 8 µm: 0.00225 ± 0.00036
Tb = 1060 ± 50 K
A = 0.31 ± 0.14
e = 0
Cre
dit:
NA
SA /
JPL-
Cal
tech
/ R
. Hur
t (SS
C-C
alte
ch)
New Champ: HD 189733 bAnnounced 2005 Oct 4, Bouchy et al. (French)K1-K2 star (small, cool)Rp = 1.26 RJup (bigish for a hot Jupiter)
Close (19.3 pc), V = 7.67Many times higher S/N than HD 209458 bGood enough for spectroscopy!
HD 189733 b 16 µm Data
Deming et al. (2006)
HD 189733 b is round!Derivative of lightcurve shows planet crossing limbDetect that planet is roundCannot detect difference between uniform and peaked emissionShould be able to with IRAC dataConstrains hot-point lag
Dem
ing
et a
l. 20
06
HD 149026 b: The Exotic PlanetAnnounced 2005 July 1, Sato et al. (Fischer/N2K)Saturn-sized, but much heavier: ~80 M⊕ core!
Large G star → very weak eclipse (0.003 mag)
N2K team, 2005 N2K
team
, 200
5
Spitzer ObservationsPredicted 3-6 in one eclipse, most favorable bandBright star → IRAC 8-µm subarray mode, 3232 pix48,384 frames, 0.4-sec frame rate, 6 hDo not expect to see eclipse in raw data!
Digging
Model
Eclipse!
Temperatures
Extrasolar Planets Encyclopedia, Deming et al. (2006,2005b),Charbonneau et al. (2005a)
Upsilon Andromedae b Team
Joseph Harrington, University of Central Florida, CornellBrad Hansen, UCLAStatia Luszcz, Cornell, UC BerkeleySara Seager, Carnegie Institution of WashingtonDrake Deming, NASA's Goddard Space Flight CenterKristen Menou, ColumbiaJames Y.-K. Cho, Queen Mary, University of LondonL. Jeremy Richardson, NASA's Goddard Space Flight Center
Image and animation: NASA/JPL-Caltech/Robert Hurt
Fire and Ice on Upsilon Andromedae b
● Upsilon Andromedae b: “hot Jupiter” planet
● Observed at 24 m by Spitzer Space Telescope, MIPS instrument (Multiband Imaging Photometer for Spitzer)
● Brightness variation tells us there is a "hot spot" facing the star
● Very different from Jupiter: Huge temperature swings from day to night side (1400 K)
Consistent with 0 phase lag (11 15)
Upsilon Andromedae b Observations
● First measurement of light from a non-transiting extrasolar planet
● First detection of temperature variation on an extrasolar planet
● Birth of exoplanetary meteorology: radiation dominates advection
● More, brighter planets now measurable by Spitzer
● Spitzer pushed well beyond specs
Spitzer SE Spectroscopy
Divide that booming signal into a few hundred channels...But also divide stellar and zodiStare as planet goes behind starHD 209458b (Richardson et al. 2007, Nature)HD 189733b (Grillmair et al. 2007, ApJ)HD 209458b (Swain et al. 2007 submitted)
HD 209458b
2 eclipsesDetect continuumTentatively detect 2 molecular emissions! (first)
HD 189733b
ContinuumNO molecular claimNOTE: Models say won't see water that is there
ConclusionsSpitzer can do more than it was designed to doSpitzer can only do planets around nearby stars!We have one more year of cold SpitzerMost important survey goal this year:FIND ALL THE NEARBY TRANSITING PLANETSGoing forward, no more Hubblephobia:STOP UNDERSPECING INSTRUMENTS!
Pay for what you can get
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DPS 2007 is in Orlando!Special Session on ExoplanetsTuesday, 9 October 2007 and...UCF is looking for grads, postdocs, faculty!Funds for dedicated 50-100 CPU cluster