Recent outburst of the young star V1180 Cas

TL;DR

This study documents the recent outburst of young star V1180 Cas, providing evidence of accretion-driven brightness variations, jet structures, and quantifying mass accretion and loss rates through multi-wavelength observations.

Contribution

It presents the first evidence of jet structures around V1180 Cas and refines the mass accretion rate estimate during its outburst.

Findings

Detection of jet structures around V1180 Cas.

Mass accretion rate estimated at ~3E-8 Msun/yr.

Observation of mass-loss phenomena via H2 imaging.

Abstract

We report on the ongoing outburst of the young variable V1180 Cas, which is known to display characteristics in common with EXor eruptive variables. We present results that support the scenario of an accretion-driven nature of the brightness variations of the object and provide the first evidence of jet structures around the source. We monitored the recent flux variations of the target in the Rc, J, H, and K bands. New optical and near-IR spectra taken during the current high state of V1180 Cas are presented, in conjunction with H2 narrow-band imaging of the source. Observed near-IR colour variations are analogous to those observed in EXors and consistent with excess emission originating from an accretion event. The spectra show numerous emission lines, which indicates accretion, ejection of matter, and an active disc. Using optical and near-IR emission features we derive a mass accretion rate of ~3 E-8 Msun/yr, which is an order of magnitude lower than previous estimates. In addition, a mass loss rate of ~4 E-9 and ~4 E-10 Msun/yr are estimated from atomic forbidden lines and H2, respectively. Our H2 imaging reveals two bright knots of emission around the source and the nearby optically invisible star V1180 Cas B, clearly indicative of mass-loss phenomena. Higher resolution observations of the detected jet will help to clarify whether V1180 Cas is the driving source and to determine the relation between the observed knots.