Light curves of the latest FUor: Indication of a close binary

TL;DR

This study presents extensive optical and near-infrared monitoring of the FUor star 2MASS J06593158-0405277, revealing brightness variations, a potential binary system, and extinction effects, enhancing understanding of FUor outburst behaviors.

Contribution

It provides the first detailed multi-wavelength light curve analysis of this FUor, suggesting the presence of a close binary system with an eccentric orbit based on observed periodic modulations.

Findings

Brightness declined due to increasing extinction.

Detected a 17-day oscillation pattern in light curves.

Indications of a close binary system with an eccentric orbit.

Abstract

We monitored the recent FUor 2MASS J06593158-0405277 (V960 Mon) since November 2009 at various observatories and multiple wavelengths. After the outburst by nearly 2.9 mag in $r$ around September 2014 the brightness gently fades until April 2015 by nearly 1 mag in $U$ and 0.5 mag in $z$. Thereafter the brightness at $\lambda>5000 \AA$ was constant until June 2015 while the shortest wavelengths ($U, B$) indicate a new rise, similar to that seen for the FUor V2493 Cyg (HBC722). Our near-infrared (NIR) monitoring between December 2014 and April 2015 shows a smaller outburst amplitude ($\sim$2 mag) and a smaller (0.2 $-$ 0.3 mag) post-outburst brightness decline. Optical and NIR color-magnitude diagrams indicate that the brightness decline is caused by growing extinction. The post-outburst light curves are modulated by an oscillating color-neutral pattern with a period of about 17 days and an amplitude declining from $\sim$0.08 mag in October 2014 to $\sim$0.04 mag in May 2015. The properties of the oscillating pattern lead us to suggest the presence of a close binary with eccentric orbit.