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

Ads

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