Radial velocity and atmospheric parameter calculations for the GaiaNIR spectrograph

Meszaros, S, Hobbs, D, Liptrott, A, Katz, D, Schiavon, R ORCID: 0000-0002-2244-0897, Pap, V, Brown, AGA, Seabroke, G, Bland-Hawthorn, J, Blomme, R and Walton, NA (2026) Radial velocity and atmospheric parameter calculations for the GaiaNIR spectrograph. Astronomy & Astrophysics, 713. pp. 1-14. ISSN 0004-6361

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Abstract

Context. The upcoming GaiaNIR mission is currently planning to add a near-infrared spectrograph to its payload in order to enhance its scientific return, particularly for mapping the dust-obscured regions of the Milky Way.
Aims. This study aims to identify the optimal wavelength region between 800 and 2300 nm for the proposed GaiaNIR spectrograph to maximize the precision of radial velocities and atmospheric parameters.
Methods. To find its spectral range, we generated 10000 synthetic spectra from the BOSZ library across a wide range of stellar parameters, with resolutions varying from 5000 to 20000. By cross-correlating these mock observations with ideal templates, we assessed the statistical scatter of velocity residuals to isolate six candidate windows for further atmospheric parameter testing.
Results. Our analysis finds that the 1926 - 1968 nm window at R = 16100 - 20100 in the K-band is the preferred strategic choice, because it has the potential to reach radial velocity precision for the brightest FGKM stars of about 160 - 260 m/s depending on resolution, while providing precision of the atmospheric parameters close to Gaia's Radial Velocity Spectrometer. We also identified a second region between 1158 and 1202 nm (R = 9300 - 11600), that has slightly lower radial velocity precision, but at a wider temperature range than the K-band. Both regions make it possible to derive abundances of ten species at these resolutions: O, Na, Mg, Si, Ca, Ti, V, Cr, Mn, Ni in the K-band, and Mg, Si, K, Ca, Ti, V, Cr, Mn, Co, Ni between 1158 - 1202 nm.
Conclusions. The K-band delivers sufficiently precise measurements for the mission's primary cool star targets while taking advantage of significantly lower interstellar extinction, enabling the mapping of the dust-obscured regions of the Milky Way.

Item Type:	Article
Uncontrolled Keywords:	instrumentation: spectrographs; Galaxy: abundances; Galaxy: fundamental parameters; astro-ph.IM; astro-ph.IM; astro-ph.SR; 5109 Space Sciences; 51 Physical Sciences; 5101 Astronomical Sciences; 5101 Astronomical Sciences; 51 Physical Sciences; 0201 Astronomical and Space Sciences; Astronomy & Astrophysics; 5101 Astronomical sciences; 5107 Particle and high energy physics; 5109 Space sciences
Subjects:	Q Science > QB Astronomy
Divisions:	Astrophysics Research Institute
Publisher:	EDP Sciences
Date of acceptance:	17 July 2026
Date of first compliant Open Access:	29 October 2026
Date Deposited:	29 Oct 2026 15:05
Last Modified:	29 Oct 2026 15:05
DOI or ID number:	10.1051/0004-6361/202661339
URI:	https://researchonline.ljmu.ac.uk/id/eprint/29767

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