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