Exoplanet Transits and SONGAngelle Tanner

The Transit Method

Venus Transiting the Sun

Information from TransitsTransit Frequency

gives us ORBIT SIZE

Orbit Size with Star Temperature tells us if planet is in habitable zone.

Transit duration, depth, gives us PLANET SIZE

Size and Mass (with a doppler measurement of the “wobble”) gives DENSITY

Density is clue to COMPOSITION.

Two Types of TransitsPrimary Transmission spectrumTerminator

SecondaryEmission spectrumDayside

Primary Eclipse

Secondary Eclipse

See thermal radiation from planet disappear and reappear

See radiation from star transmittedThrough the planet’s atmosphere

Because we can study their atmospheres!

Transiting planets are exciting …

The Rossiter-McLaughlin effect

SONG could: Make RV measurements during transit to determine the angle between stellar rotation and planet orbital plane

Transit, the First – HD 209458

Left: Charbonneau, D., Brown, T., Latham, D. et al, 2000, ApJ 529, L45 Right: Brown, T., Charbonneau, D., Gilliland, R. et al, 2001, ApJ 552, 699

Currently 166 confirmed transiting systems

Kepler

Goal: To find transiting habitable Earths

Kepler Highlights

Mar 7, 2009 – launch!Aug 6, 2009 – confirmed HAT-P-7b2010 – six confirmed systemsJune 15, 2010 – 706 planet candidates

2011 – 4 confirmed systems thus farFeb 2, 2011 – 1235 planet candidates, 54 in HZ Kepler-11 system with 7 planets

Two days ago – Kepler 16b – Tatooine planet!!

~1200 Kepler candidate planets

54 are in The HZ!

Mearth Currently monitoring 3000 M dwarfs8 40 cm telescopes, with 26’ CCD FOVAt Mt Hopkins, AZ with plans to go South

M4.5, V=14.6, K=12.2 m/s Charbonneau et al. 2009

No features seen in ground based transmission spectrum – Bean et al. 2010

GJ 1214 – the lightest star w/ a planet

• They are abundant and close• We are sensitive to lighter planets• RV surveys reach the habitable zone• Once found, they make ideal planet transit targets

Km/s0.100.320.602.235.73

MV MK

4.8 3.39.0 5.311.7 6.816.6 9.419.4 10.5

Why M dwarfs are COOL …

SONG and the Late type stars

Stars within 25 pcRed = V < 8

SONG could: 1) Follow-up the brightest Mearth candidates, 2) Follow-up Kepler candidates, or 3) do its own survey of K/M stars

RV Jitter: What is its impact on planet detection?

Sunspots/PlagePulsationsGranulationFlares

What we know about jitter from the FGKs (uh, nothing?)

Barnard’s star shows and anti-correlation between Hα and RV jitter - Zechmeister et al 2009

S-index indicator not necessarily correlated with RV jitter (Wright et al. 2009)

Other indicators such as SHK and log R’HK also don’t always correlate with RV jitter (Fischer & Issacson 2010)

Integrate over p-mode periods to push below 1 m/s?

P-modes for α Cen A (Butler et al., Fischer et al. )

Starspots could be problematic for M dwarfs

T*= 2800 K & Tspot = 2600 K

Vsini=2 km/s Vsini=10 km/sσRV ~ 10 m/s 14 m/s @ 0.5 micσRV ~ 2 m/s 10 m/s @ 1.0 micσRV ~ 2 m/s 10 m/s @ 1.6 mic

NO detections < 20 Me for < 500observations fo vsini > 20 m/s – Barnes et al 2010

SONG could: Perform intense studies of RV jitter noise as a function of spectral type

SONG CAN contribute to transiting exoplanet research

1) Follow-up for Rossiter-McLaughlin effect2) Follow-up for Mearth, Kepler and other

transit detections3) RV jitter studies with simultaneous

photometric monitoring

4) ????