Gaia20dsk: A new MNor discovered by the GLORIOUS collaboration

TL;DR

Gaia20dsk is a young eruptive star exhibiting multiple brightness bursts, with spectral and accretion features confirming its classification as an MNor-type young stellar object.

Contribution

This study provides the first detailed physical and accretion analysis of Gaia20dsk, confirming its classification as an MNor-type eruptive young star.

Findings

Gaia20dsk experienced two major brightness bursts with ~1.8 mag amplitude.

Spectroscopic features are consistent with accreting low-to-intermediate-mass YSOs.

Mass accretion rate during bursts is estimated between 0.5 and 1.8 x 10^{-6} M_sun/yr.

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 a 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_sun/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.