Speaker
Description
We aim to determine the optimal wavelength region for the GaiaNIR spectrograph to maximize radial velocity and atmospheric parameter precision (Teff, log g, [M/H]) between 800 and 2300 nm. To achieve this, we generated 10,000 synthetic spectra using the BOSZ library, spanning a wide range of stellar parameters, resolutions (R=5000–20,000), and signal-to-noise ratios. Radial velocities were derived by cross-correlating these mock observations with ideal, noise-free templates. We analyzed the statistical scatter and 95th percentile of the velocity residuals to subsequently selected four candidate windows for detailed atmospheric parameter testing.
We further explored the precision of atmospheric parameters, and what abundances are available in the four candidate windows to make our final selection for the wavelength range of the spectrograph. Our results demonstrate that while the 845–885 nm region yields the highest intrinsic precision for most parameters, the 1926–1998 nm window represents the preferred strategic choice. It provides sufficiently precise radial velocities and atmospheric parameters for the mission's key targets—cool stars across a wide metallicity range—while leveraging the reduced extinction of the K-band to probe the dust-obscured structure of the Milky Way.
