Gaia Data Release 3. Properties of the line-broadening parameter derived with the Radial Velocity Spectrometer (RVS)

Frémat, Y. ; Royer, F. ; Marchal, O. ; Blomme, R. ; ... ; Lobel, A. ; ... ; Samaras, N. ;  et al
June, 2023

 

Abstract :

Context. The third release of the Gaia catalogue contains radial velocities for 33 812 183 stars with effective temperatures ranging from 3100 K to 14 500 K. The measurements are based on the comparison of the spectra observed with the Radial Velocity Spectrometer (RVS; wavelength coverage: 846-870 nm, median resolving power: 11 500) to synthetic data broadened to the adequate along-scan line spread function. The additional line-broadening, fitted as it would only be due to axial rotation, is also produced by the pipeline and is available in the catalogue (field name vbroad).
Aims: We describe the properties of the line-broadening information extracted from the RVS and published in the catalogue, and analyse the limitations imposed by the adopted method, wavelength range, and instrument.
Methods: We used simulations to express the link between the line-broadening measurement provided in Gaia Data Release 3 and V sin i. We then compared the observed values to the measurements published by various catalogues and surveys (GALAH, APOGEE, LAMOST, etc.).
Results: While we recommend caution in the interpretation of the vbroad measurement, we also find a reasonable general agreement of the Gaia Data Release 3 line-broadening values and values in other catalogues. We discuss and establish the validity domain of the published vbroad values. The estimate tends to be overestimated at the lower V sin i end, and at Teff > 7500 K its quality and significance degrade rapidly when GRVS > 10. Despite all the known and reported limitations, the Gaia Data Release 3 line-broadening catalogue contains measurements obtained for 3 524 677 stars with Teff ranging from 3500 to 14 500 K, and GRVS < 12. It gathers the largest stellar sample ever considered for the purpose, and allows a first mapping of the Gaia line-broadening parameter across the Hertzsprung-Russel diagram.

 

Publication : Astronomy & Astrophysics, Volume 674, id.A8, 19 pp.
DOI : 10.1051/0004-6361/202243809
Bibcode : 2023A&A...674A...8F
Keywords : stars: rotation; catalogs; Astrophysics - Solar and Stellar Astrophysics; Astrophysics - Astrophysics of Galaxies