IRD: New Near-Infrared Spectrograph for Exoplanet Search around Low-mass Stars
Teruyuki Hirano
Tokyo Institute of Technology



Unlike solar-type stars, low-mass stars (particularly later than mid M dwarfs), are relatively unexplored in exoplanet searches due to their intrinsic faintness. Nonetheless, low-mass stars are great targets to search for Earth-like planets in the habitable zone (HZ), since for low-mass stars (1) the HZ is very close to the central stars, and (2) their small mass and radius produce larger observational signals in the radial velocity (RV) and transit methods. Since low-mass stars are brighter in the near infrared (NIR), several groups in the world have developed (are developing) spectrographs to measure precise RVs in the NIR. In this talk, I will introduce our effort to develop the InfraRed Doppler (IRD) instrument, which was installed on the Subaru 8.2m telescope last year. IRD is a temperature-stabilized, fiber-fed spectrograph, and the laser frequency comb is used for the simultaneous wavelength calibration. Conducting three engineering runs since last August as well as the intensive stability tests in the laboratory, we have demonstrated that IRD can achieve an RV precision of ~2 m/s on a short timescale. I will review the specification of the spectrograph and simulated RV precisions that IRD can achieve, as well as our observing plan and goals of the strategic exoplanet RV survey that we will conduct with IRD. I will also introduce some science cases that we can do with the IRD spectrograph.