[P-EM11] Exoplanet

[PEM11-19] Development for the South Africa Near-infrared Doppler (SAND) instrument

*Aoi Takahashi^1,2, Takayuki Kotani^1,2,8, Jun Nishikawa^2,1,8, Akitoshi Ueda², Masayuki Kuzuhasa^1,2, Ko Hosokawa^8,2, Shotaro Tada^8,2, Motohide Tamura^3,1,2, Takahiro Nagayama⁴, Takuma Kokusyo⁵, Eiko Kozaki⁵, Takahiro Sumi⁶, Bun'ei Sato⁷, Teruyuki Hirano^1,2,8, Takuya Takarada^1,2, Masashi Omiya^1,2 (1.National Institutes of Natural Sciences, Astrobiology Center, 2.National Institutes of Natural Sciences, National Astronomical Observatory of Japan, 3.University of Tokyo, 4.Kagoshima University, 5.Nagoya University, 6.Osaka University, 7.Tokyo Institute of Technology, 8.The Graduate University for Advanced Studies)

Keywords:radial velocity, near infrared, spectrograph

The number of detections of young planets is not sufficient yet to constrain planetary formation process. Besides, it is extremely important for astrobiology to detect and characterize a greater number of rocky planets whose orbit is located in a habitable zone. We aim to the precise radial velocity (RV) measurements to search for both giant planets around young stars and rocky planets in a habitable zone around nearby M-dwarfs.
Based on the motivations, we are developing a high-resolution near-infrared spectrograph for telescopes in Sutherland, South Africa; the South Africa Near-infrared Doppler (SAND) instrument. It covers the z- and Y-bands (840-1090 nm) simultaneously with a spectral resolution of 60,000.
The SAND is a fiber-fed instrument and, therefore, can be installed into multiple telescopes at the same site by changing the fiber connection. It will be operated mainly on the PRIME telescope, which is newly developed by Osaka University. The InfraRed Survey Facility (IRSF) and the Southern African Large Telescope (SALT) are also candidate telescopes for the installation. Such collaboration with multiple telescopes is unique and enables frequent and flexible RV-monitoring.
Inside the SAND spectrograph, a star image ejected from the fiber is sliced half and each sliced image is spectrally dispersed by an echelle grating. As a reference source for the wavelength calibration, light transmitted by a Fabry-Perot Etalon is simultaneously injected into the spectrograph and share the almost identical optical pass. It can mitigate the RV error originating from instrumental instability, by focusing on the positions of stellar absorption lines relative to the reference spectrum.
We are planning a long-term RV survey for targets in young stellar associations and nearby M-dwarfs at the southern sky since 2024. We expect the RV precision of 5 and 2 m/s for a young G-type star and matured nearby M-dwarfs, respectively, considering the stellar photon noise with a 30-mintutes exposure.