Infrared Doppler for the Subaru telescope: Survey plan and the current status of the instrument

Transcription

1 Infrared Doppler for the Subaru telescope: Survey plan and the current status of the instrument Takayuki Kotani (NAOJ), Motohide Tamura, Hiroshi Suto, Jun nishikawa, Bun ei Sato, Wak Aoki, Tomonori Usuda, Takashi Kurokawa, Ken Kashiwagi, Shogo nishiyama, Yuji Ikeda, Donald B. Hall, Klaus W. Hodapp, Shne Jacobson, Jun Hashimoto, Jun-Ichi Morino, Yasushi Okuyama, Yosuke Tanaka, Shota Suzuki, Jungmi Kwon, Takuya Suenaga, Dehyun Oh, Haruka Baba, Norio Narita, Eiichiro Kokubo, Yutaka Hayano, Hideyuki Izumiura, Eiji Kambe, Tomoyuki Kudo, Nobuhiko Kusakabe, Masahiro Ikoma Hori, Masashi Omiya, Hidenori Genda, Akihiko Fukui, Yuka Fujii, Olivier Guyon, Hiroki Harakawa, Masahiko Hayashi, Masahide Hidai, Teruyuki Hirano, Masayuki Kuzuhara, Masahiro Machida, Taro Matsuo, Tetsuya Nagata, Hirohi Onuki, Masahiro Ogihara, Hideki Takami, Naruhisa Takato, Yasuhiro H.Takahashi, Chihiro Tachinami, Hiroshi Terada, Hajime Kawahara IRD tem

2 Planet mass (M Earth ) Detection limit of RV survey Next step in Exoplanet science: Understandings of Earth-like planets in their habitable zone (HZ) >30M Earth : 10-30M Earth 3-10M Earth 0.5-3M Earth 0.5-5M : 1000 Jupiter Earth 100 Habitable Earth-mass planets around solar type stars cannot be reached with the currently available technology 10 Low-mass planets around low mass stars 1 M dwarfs 0.2M Sun Solar type stars 1.0M Sun Rad ial velocity Tran sit Direct Im ag ing M icrolensing Astrom etry AU Semi-major axis (AU)

3 Current status of the study of Earth-like planets Earth Masses or Earth Radii in conservative Habitable zone Planets detected by survey of nearby low-mass stars Early K-M dwarfs Planet mass > 3.8M Earth Planets detected by Kepler Follow-up is difficult No doppler measurements (mass is unknown) 1. No Earth-like (mass, radius, temperature) planets are detected around nearby stars 2. Number of detected habitable planets is not enough for statistical study

4 Infrared Doppler (IRD) for the Subaru telescope What is IRD? High-resolution, NIR spectrometer for the Subaru for planet detection by radial velocity method First light will be in the end of 2015, start of a survey in 2016 Goal of IRD Detection of ~ 50 planets around nearby M dwarfs, including ~10 Earth-like planets in their habitable zone Uniqueness of IRD One Earth-mass planet in HZ around a lowmass M dwarf (late-type M dwarf) can be detected Late M dwarfs are too faint to observe with optical/3-meter class IR Doppler Wide spectral coverage (J,H,K)

5 Science goals of IRD 1. Detection of habitabile Earth-like planets around nearby M dwarfs Minimum Success Detection of at least 1, one Earth-mass planet in their HZ Full Success Unveiling frequency and properties of habitable Earth 2. Statistical understandings of planet formation around low-mass stars Minimum Success 25 > Super-Earth - Jupiter-mass planets around lowmass s stars Full Success 50> planets including Earth-mass planets Number of Detection >1 >10 >25 >50 The expected number of planets is estimated by planet population synthesis and with observing schedule simulation

6 Target stars ~ 100 Start of survey:2016~ Other groups will start a survey around 2016, but mainly for early M dwarfs Required observing night 170 night (Strategic program) Period: 5 years Planned schedule: 2014/11/13 Telescope schedule Observation Plan 0.5 night 7/month 9~10 run/year Half night allocation is important to better sample planet orbital period Expected number of planets to be discovered: Total>50 Earth-mass planets : ~ 28 Habitable Earth and Super Earths: ~10 Example of scheduling S1?B IRD S1?B IRD S1?B IRD S1?B IRD S1?B IRD S1?B IRD S1?B IRD 0.5 night 7 1/1

7 Instrument development status Spectral coverage Spectral resolution Fiber Grating RV precision Detector Cryogenic system μm 1480nm(3pixel sampling) star + comb, a multi-mode or single-mode fiber Echelle & VPH-Grating (order sorting) 1 m/s w/ laser frequency comb Hawaii 4RG 4096x4096 Detector: 60K, Optics: 200K, Pulse-tube cooler 2010: Project started 2012: Conceptual Design Review : Integration, test of the instruments End of 2015: First light at the Subaru telescope 2016: Start of a survey

8 Overview of the IRD instrument Laser Comb Mode scrambler Star light From AO Fiber injection system (AO bench) Resolution: R=70000 Wavelength: um Cryo: 60K (detector), 200K (optics) Fiber (Comb) Fiber (star) Laser frequency comb (IR Observing floor) spectrometer Coudé Room Spectrometer system (Coudé room)

9 600mm 1300mm Spectrometer Optics Fiber array with 2x MMF+ 2x SMF F-conversion: F3.33(fiber) F12.6 (slit) Slit: 0.27x2.2 High blaze angle Echelle grating Camera system Hawaii4RG VPH Grating Slit Fibers F-conversion unit Collimator Echelle grating (80.7 deg blaze angle, 75um pitch)

10 Ultra Low-CTE ceramic optical bench & optics Collimator Flat mirror 600mm Slit holder 100mm Optical bench 1300mm Mirror, holder, and optical bench are made of low CTE ceramic (CTE <0.05E-6) Mirror has good surface roughness (<2nm Ra), surface quality (<λ/4 PV, λ=633nm) High reflectance after gold coating (>98% from 0.97 to 1.75um) All components are precisely machined and positioned by suing a 3D coordinate-measuring machine Ceramic is from Kyocera

11 Original Laser frequency comb 980nm Our original laser frequency comb will cover Y, J, H-band simultaneously Sufficiently wide frequency span(12.5ghz, 1.5um) Developed by the Tokyo University of Agriculture and Technology

12 Laser frequency comb spectrum Full coverage of Y,J,H-band will be achieved soon

13 Chamber and cryogenic system Radiation shield covered with MLI Vibration damper Ceramic optical bench (~200K) Kinematic mount/radiation shied base Pulse-tube cooler

14 Large format infrared array : Teledyne H4RG15 Under development, Collaboration with IfA, University of Hawaii

15 Conclusions IRD is a NIR high-resolution spectrometer for the Subaru telescope for very precise RV measurements (~ 1m/s) IRD aims at detecting ~50 planets around nearby M dwarfs, including 10 Earth-like planets in habitable zone IRD will survey ~ 100 late M-dwarfs for 5 years and SSP is planned Integration and test of the instruments is ongoing, and a survey will start in 2016