V2494 Cyg: A unique FU Ori type object in the Cygnus OB7 complex

TL;DR

This paper presents a detailed photometric and spectral analysis of V2494 Cyg, a unique FU Ori type star in Cygnus OB7, highlighting its outburst, jet activity, and extended outflow, marking it as the first FUor with both features.

Contribution

It provides the first detailed study of V2494 Cyg's outburst, jet, and extended outflow, establishing it as a unique FUor object with both phenomena observed.

Findings

V2494 Cyg experienced a 2.5 mag brightness increase in the 1980s.

The star exhibits FU Ori spectral features and strong emission lines.

It has a parsec-sized HH flow associated with its outburst.

Abstract

A photometric and spectral study of the variable star V2494 Cyg in the L 1003 dark cloud is presented. The brightness of the star, formerly known as HH 381 IRS, increased by 2.5 mag in R (probably in the 1980s) and since then has remained nearly constant. Since the brightness increase, V2494 Cyg has illuminated a bipolar cometary nebula. The stellar spectrum has several features typical of the FU Ori type, plus it exhibits very strong Halpha and forbidden emission lines with high-velocity components. These emission lines originate in the HH jet near the star. The kinematic age of the jet is consistent with it forming at the time of the outburst leading to the luminosity increase. V2494 Cyg also produces a rather extended outflow; it is the first known FUor with both an observed outburst and a parsec-sized HH flow. The nebula, illuminated by V2494 Cyg, possesses similar morphological and spectral characteristics to Hubble's Variable Nebula (R Monocerotis/NGC 2261).