Gaia20dsk: A new MNor discovered by the GLORIOUS collaboration

¹ Konkoly Observatory, HUN-REN Research Centre for Astronomy and Earth Sciences, MTA Centre of Excellence, Konkoly-Thege Miklós út 15–17, 1121 Budapest, Hungary
² Institute of Physics and Astronomy, ELTE Eötvös Loránd University, Pázmány Péter sétány 1/A, 1117 Budapest, Hungary
³ Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, UT3-PS, OMP, CNRS, 9 av. du Colonel-Roche, 31028 Toulouse Cedex 4, France
⁴ Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
⁵ Instituto de Astrofísica de Canarias, IAC, Vía Láctea s/n, 38205 La Laguna (S.C. Tenerife), Spain
⁶ Departamento de Astrofísica, Universidad de La Laguna, 38206 La Laguna (S.C. Tenerife), Spain
⁷ Scottish Universities Physics Alliance (SUPA), School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews KY16 9SS, UK
⁸ Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
⁹ Mt. Suhora Astronomical Observatory, University of the National Education Commission, ul. Podchorazych 2, 30-084 Krakow, Poland
¹⁰ INAF – Osservatorio Astronomico di Roma, Via di Frascati, 33, 00078 Monte Porzio Catone, Italy
¹¹ ASI, Italian Space Agency, Vi del Politecnico snc, 00133 Rome, Italy
¹² Warsaw University Observatory, al. Ujazdowskie 4, 00-001 Warsaw Astrophysics Division, National Centre for Nuclear Research, Pasteura 7, 02-093 Warsaw, Poland

^★ Corresponding authors.

Received: 29 April 2025
Accepted: 18 December 2025

Abstract

Context. Among known young stellar objects (YSOs), those exhibiting the most dramatic increases in brightness due to sudden increase in mass accretion rate are eruptive young stars. Gaia20dsk is one of the Gaia-alerted young star candidates that has displayed a double, nonperiodic brightening resembling that of other young eruptive stars.

Aims. The goal of this work is to determine the physical and accretion properties of Gaia20dsk to confirm its classification as an eruptive young star.

Methods. We combined publicly available optical and near-infrared (NIR) photometry with our X-shooter optical/NIR spectrum. In our analysis, we examined the optical and IR light curves from the bursts, reviewing the color-magnitude diagrams across different bands, reporting the detection of emission lines, and providing estimates of the star’s accretion rates during the burst.

Results. The optical light curve shows two major and one brief brightening events with an maximum amplitude of ∼ 1.8 mag in the last five years. A classification based on spectral index indicates that Gaia20dsk is a flat-spectrum star. The X-shooter spectrum exhibit emission lines characteristic of accreting low-to-intermediate-mass young stars, displaying features typical of MNor-type objects. The mass accretion rate is between (0.5−1.8) × 10⁻⁶ M_⊙/yr.

Conclusions. Gaia20dsk is an eruptive YSO that exhibits photometric features similar to those of MNors, including its characteristic brightening amplitude and burst duration, along with similar spectroscopic features and accretion rates.