Post on 20-Dec-2015
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
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 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!!
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
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