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Exoplanet Transits and SONG. Angelle Tanner. The Transit Method. Venus Transiting the Sun. Information from Transits. Transit 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
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Exoplanet Transits and SONG Angelle Tanner
The Transit Method Venus Transiting the Sun
Information from Transits • Transit 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 Transits Primary Transmission spectrum Terminator Secondary Emission spectrum Dayside Secondary Eclipse See thermal radiation from planet disappear and reappear Primary Eclipse See radiation from star transmitted Through the planet’s atmosphere
Transiting planets are exciting … Because we can study their atmospheres!
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-7b 2010 – six confirmed systems June 15, 2010 – 706 planet candidates 2011 – 4 confirmed systems thus far Feb 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 dwarfs 8 40 cm telescopes, with 26’ CCD FOV At Mt Hopkins, AZ with plans to go South GJ 1214 – the lightest star w/ a planet 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
Why M dwarfs are COOL … • 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 K m/s 0.10 0.32 0.60 2.23 5.73 MV MK 4.8 3.3 9.0 5.3 11.7 6.8 16.6 9.4 19.4 10.5
SONG and the Late type stars Stars within 25 pc Red = 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
Sunspots/Plage Pulsations Granulation Flares RV Jitter: What is its impact on planet detection?
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) 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
Integrate over p-mode periods to push below 1 m/s? P-modes for αCen A (Butler et al., Fischer et al. )
Starspots could be problematic for M dwarfs T*= 2800 K & Tspot = 2600 K Vsini=2 km/sVsini=10 km/s σRV ~ 10 m/s 14 m/s @ 0.5 mic σRV ~ 2 m/s 10 m/s @ 1.0 mic σRV ~ 2 m/s 10 m/s @ 1.6 mic NO detections < 20 Me for < 500 observations fovsini > 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 • Follow-up for Rossiter-McLaughlin effect • Follow-up for Mearth, Kepler and other transit detections • RV jitter studies with simultaneous photometric monitoring • ????