Ge/Ay133

What (exo)-planetary science can be done with transits and microlensing?

A Jupiter transit across the Sun is ~1%:

Curvature?

Limb Darkening and Transit Profiles:

• Probes composition of atmosphere at day-night terminator

• Can search for clouds, hazes, condensates

HST STIS transits of HD 209458b from 290-1030 nm (Knutson et al. 2007a)

Atmosphere

Star

Planet

Sometimes the absence of signal is interesting:

No transits in 47 Tuc, `expectation’=30-40 (34,000 stars)

Gilliland, R.L. et al. 2000, ApJ, 545, L47

Transits, approach #1:

Search for transits in systems known to have planets at the doppler crossings.

Sato, B. et al. 2005, ApJ, astro-ph/0507009

Transits and the Rossiter-McLaughlin effect (1924):

Winn, J.N. et al. 2005, ApJ, 631, 1215

Photometry can be straightforward: Amateur observations of HD 209458 b

Bruce L. Gary, Santa Barbara, CA

Arto Oksanen

SBIG cameras, Meade telescopes, V filters

Transits, approach #2:

Search for transits in many stars using a suite of low cost robotic telescopes.

TrES-1

Alonso, R. et al. 2004, ApJ, 613, L153

Photometry from space can be extremely good:

HD 209458 - HST

The KEPLER mission is dedicated to photometry and can search for earth mass planets in the so- called habitable zone.

Brown, T.M. et al. 2001, ApJ, 552, 699

www.kepler.arc.nasa.gov

95 Mpixel camera, 115 deg2 FOV, 4’’ pixels

But ground-based work is making strides!

HD 209458 - HST

At this level of performance (0.47 milli-mag) the transits of hot Neptunes are detectable & transit timing can put stringent limits on perturbing planets into the Earth mass range.

Brown, T.M. et al. 2001, ApJ, 552, 699

Secondary eclipses canalso put limits on the visiblealbedo. The MOSTsatellite findsA(HD209458b)<0.25 (1) (Jupiter=0.5, 300-700 nm). Why so dark?

Rowe, J.F.. et al. 2006, ApJ, 646, 1241

Transit photometry from space: Kepler

A comparison of transiting planet systems:

As we’ll see, size is not a strong function of mass, so very accurate measurements are needed!

T = 1060 ± 50 KA = 0.31 ± 0.14

Secondaryecplises in the IR with Spitzer, see photons from the hot Jupiters!

Charbonneau, D. et al. 2005, ApJ, 626, 523

T = 1060 ± 50 KA = 0.31 ± 0.14

Charbonneau, D. et al. 2005, ApJ, 626, 523

Rapid Pace of Spitzer Transit Results: HD 189733b

Mapping the temperature variation of a hot Jupiter…

•T(max)~1200 K, T(min)~970 K•Hot spot ~30 ± 10° from the sub-stellar point•Bond albedo~0.30•Must be reasonably efficient circulation from day to night side.

Other routes to Earth-like planets?

Microlensing example:

Microlensing example:

Are there Earth-like planets beyond the snow-line?

Rapid Progress: Transiting Planets, 1 May 2007

One year later (2008): 43 Systems And Counting

Ice/Rock Planets

HD 149026

Other Correlations:

Why would the mass/gravity of a close-in planet be tied to the period?

May be some tie to the mass of the star…

B. Hansen & T. Barman 2007, ApJ, 671, 61

Other Correlations II:

For a given Teq (not strictly distance since the spectral type varies…), two classes of planets versus Safronov number?

B. Hansen & T. Barman 2007, ApJ, 671, 61

Seems also to be tied to the mass of the planets:

•Selection bias or poor stellar radii? X•Redistribution of energy? More next time…•Evaporation? X (if “hot start”)•Tidal heating?•Planetesimals & migration (tie to Safronov #)?

Need composition(s)!B. Hansen & T. Barman 2007, ApJ, 671, 61