The X-shooter Spectral Library (XSL): Data Release 3^⋆

¹ Kapteyn Astronomical Institute, University of Groningen, Landleven 12, 9747 AD Groningen, The Netherlands
e-mail: verro@astro.rug.nl
² Observatoire Astronomique de Strasbourg, Université de Strasbourg, CNRS, UMR 7550, 11 rue de l’Université, 67000 Strasbourg, France
³ Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
⁴ ESO, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany
⁵ CRAL-Observatoire de Lyon, Université de Lyon, Lyon I, CNRS, UMR5574, St-Genis-Laval, France
⁶ New York University Abu Dhabi, Abu Dhabi, PO Box 129188 Abu Dhabi, UAE
⁷ Instituto de Astrofísica de Canarias, Vía Láctea s/n, La Laguna, Tenerife, Spain
⁸ Departamento de Astrofísica, Universidad de La Laguna, 38205 La Laguna, Tenerife, Spain
⁹ Departamento de Física de la Tierra y Astrofísica, UCM, 28040 Madrid, Spain
¹⁰ Universidade de São Paulo, Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Rua do Matão 1226, 05508-090 São Paulo, Brazil
¹¹ NAT – Universidade Cidade de São Paulo, Rua Galvão Bueno, 868, São Paulo, Brazil

Received: 7 October 2021
Accepted: 29 November 2021

Abstract

We present the third data release (DR3) of the X-shooter Spectral Library (XSL). This moderate-to-high resolution, near-ultraviolet-to-near-infrared (350–2480 nm, R ∼ 10 000) spectral library is composed of 830 stellar spectra of 683 stars. DR3 improves upon the previous data release by providing the combined de-reddened spectra of the three X-shooter segments over the full 350–2480 nm wavelength range. It also includes additional 20 M-dwarf spectra from the ESO archive. We provide detailed comparisons between this library and Gaia EDR3, MILES, NGSL, CaT library, and (E-)IRTF. The normalised rms deviation is better than D = 0.05 or 5% for the majority of spectra in common between MILES (144 spectra of 180), NGSL (112/116), and (E-)IRTF (55/77) libraries. Comparing synthetic colours of those spectra reveals only negligible offsets and small rms scatter, such as the median offset(rms) 0.001 ± 0.040 mag in the (box1 − box2) colour of the UVB arm, −0.004 ± 0.028 mag in (box3 − box4) of the VIS arm, and −0.001 ± 0.045 mag in (box2 − box3) colour between the UVB and VIS arms, when comparing stars in common with MILES. We also find an excellent agreement between the Gaia published (BP − RP) colours and those measured from the XSL DR3 spectra, with a zero median offset and an rms scatter of 0.037 mag for 449 non-variable stars. The unmatched characteristics of this library, which combine a relatively high resolution, a large number of stars, and an extended wavelength coverage, will help us to bridge the gap between the optical and the near-IR studies of intermediate and old stellar populations, and to probe low-mass stellar systems.