Searching for Planets orbiting M Dwarfs with the TripleSpec Exoplanet Discovery Instrument (TEDI)...
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Transcript of Searching for Planets orbiting M Dwarfs with the TripleSpec Exoplanet Discovery Instrument (TEDI)...
Searching for Planets orbiting M Dwarfs with the
TripleSpec Exoplanet Discovery Instrument (TEDI)
Philip Muirhead (me, Cornell)
James Lloyd (my Advisor, Cornell)
Jerry Edelstein (Berkeley)
David Erskine (LLNL)
Jason Wright (Penn State)
Matthew Muterspaugh (Tenn State)
Berkeley Undergraduates:
Tony Mercer, Aga Czeszumska,
Sam Halverson, Danny Mondo
M Dwarfs1000x fainter than Sun-like stars in the visible
Vega
Sun
M Dwarfsdominate the Galaxy by number
Gl 581
HD 41004BGl 317
Exoplanet Host Stars Discovered by Doppler Method
V < 12
Gl 581
HD 41004BGl 317
Exoplanet Host Stars Discovered by Doppler Method
V < 12
K < 12
Gl 581
HD 41004BGl 317
Exoplanet Host Stars Discovered by Doppler Method
V < 12
K < 12
Dwarfs culled using Proper MotionLepine & Shara 2005Nutzman & Charbonneau 2007
Gl 581
HD 41004BGl 317
Exoplanet Host Stars Discovered by Doppler Method
V < 12
K < 12
Dwarfs culled using Proper MotionLepine & Shara 2005Nutzman & Charbonneau 2007
Infrared Doppler Survey Science Targets
Infrared Doppler Survey Science Targets
Graphic from Eggenberger & Udry 2009
Precise Doppler Methods in Optical
Multi-mode Hi Res
(moving parts OK)
Single-mode Hi Res
(moving parts not OK)
Precise Doppler Methods in Near-IR?
Multi-mode Hi Res
(moving parts OK)
Single-mode Hi Res
(moving parts not OK)
Graphic from Eggenberger & Udry 2009
Precise Doppler Methods in Near-IR?
Multi-mode Hi Res
(moving parts OK)
Single-mode Hi Res
(moving parts not OK)
Graphic from Eggenberger & Udry 2009
Precise Doppler Methods in Near-IR?
Multi-mode Hi Res
(moving parts OK)
Single-mode Hi Res
(moving parts not OK)
Graphic from Eggenberger & Udry 2009
$$$$
Our Method: TEDI
MirrorsBeam SplitterEtalon (Glass)
Michelson-Morley Interferometer with adjustable optical DELAY
Interferometer fully adjustable (NOT monolithic)
Erskine 2003, Ge 2006
Single-Mode, NIRModerate-res Spectrograph
Our Method: TEDI
MirrorsBeam SplitterEtalon (Glass)
Single-Mode, NIRModerate-res Spectrograph
Michelson-Morley Interferometer with imposed optical DELAY
Interferometer fully adjustable (NOT monolithic)
Erskine 2003, Ge 2006
Our Method: TEDI
MirrorsBeam SplitterEtalon (Glass)
Single-Mode, NIRModerate-res Spectrograph
Michelson-Morley Interferometer with imposed optical DELAY
Interferometer fully adjustable (NOT monolithic)
Erskine 2003, Ge 2006
One TripleSpec Pixel
1 km/s Doppler Shift
Advantages of the Method
• The Doppler signal is shifted from a pixel-to-pixel flux change to a flux change within a pixel– Highly insensitive to pixel-to-pixel calibration– Extremely sensitive to delay calibration– Delay is simultaneously calibrated with overlapped
ThAr lamp emission lines.
• Moderate Resolution Spectrograph allows for broad simultaneous wavelength coverage– 0.9 to 2.5 microns, JHK
GJ 411M2V, K=3.3, vsini < 1km/s, δRV < 5m/s
Examine Line Core
GJ 411M2V, K=3.3, vsini < 1km/s, δRV < 5m/s
Modeled and Removed ThAr Line
GJ 411M2V, K=3.3, vsini < 1km/s, δRV < 5m/s
GJ 411M2V, K=3.3, vsini < 1km/s, δRV < 5m/s
σφ = 10° = 300 m/s in ONE PIXEL
With 1000s of pixels that’s
σ<φ>= 10 m/s
Challenges
• Wavelength Dependent Systematics– Telluric Contamination (calibration promising)– Wavelength dependent delay, related to focus
changes (calibration also promising)
• Throughput Below Spec– 10m/s in 6 min on K=3.3, the same as– 30m/s in 1 hour on K=8.3 (science targets)– Factor of 10 in throughput loss yet unaccounted
for
Summary
• TEDI designed to detect planets orbiting M dwarfs with the Doppler technique in NIR.
• Potential for detecting habitable worlds.• Uses an interferometer and moderate-res
spectrograph for precise radial velocimetry.• Currently achieving ~10 m/s of photon-limited
precision on bright M dwarf.• However, currently limited by systematic
effects, but calibration is promising.
Kasting & Catling 2003
5ME Planet withRV > 3m/s on host star
Gl 581c
Gl 581d
TSPEC Hawaii 2K, HgCaTe