High-resolution spectroscopic monitoring observations of FU Orionis-type object, V960 Mon

TL;DR

This study presents high-resolution spectroscopic monitoring of FU Orionis-type object V960 Mon, revealing wind variability, Keplerian disk features, and jet/outflow tracers over several years post-outburst.

Contribution

It provides detailed temporal spectroscopic data of V960 Mon, highlighting wind evolution, disk rotation characteristics, and rare jet tracers in FUors, enhancing understanding of FU Orionis outburst phenomena.

Findings

Wind features weakened over time after outburst.

Detected double-peaked line profiles indicating Keplerian disk rotation.

Identified jet/outflow tracers [S II] and H2 emission lines.

Abstract

We present the results of high-resolution (R $\ge$ 30,000) optical and near-infrared spectroscopic monitoring observations of a FU Orionis-type object, V960 Mon, which underwent an outburst in 2014 November. We have monitored this object with the Bohyunsan Optical Echelle Spectrograph (BOES) and the Immersion GRating INfrared Spectrograph (IGRINS) since 2014 December. Various features produced by a wind, disk, and outflow/jet were detected. The wind features varied over time and continually weakened after the outburst. We detected double-peaked line profiles in the optical and near-infrared, and the line widths tend to decrease with increasing wavelength, indicative of Keplerian disk rotation. The disk features in the optical and near-infrared spectra fit well with G-type and K-type stellar spectra convolved with a kernel to account for the maximum projected disk rotation velocity of about 40.3$\pm$3.8 km s$^{-1}$ and 36.3$\pm$3.9 km s$^{-1}$, respectively. We also report the detection of [S II] and H$_{2}$ emission lines, which are jet/outflow tracers and rarely found in FUors.