The Continuing Outburst of V1647~Orionis: Winter/Spring 2011 Observations

TL;DR

This paper reports on optical and near-infrared observations of the young eruptive star V1647 Orionis, documenting its repeated outbursts, persistent elevated state since 2008, and analyzing accretion rates and extinction effects over several years.

Contribution

It provides new observational data from 2011 showing the star's sustained outburst and analyzes changes in accretion luminosity and rate over multiple years, highlighting the role of extinction.

Findings

V1647 Ori remained in outburst from mid-2008 to 2011.

Accretion luminosity was approximately 16 Lsun during outbursts.

Accretion rate was about 4x10^-6 Msun/yr, declining during fading phases.

Abstract

We present optical and near-IR observations of the young eruptive variable star V1647 Orionis which illuminates McNeil's Nebula. In late 2003, V1647 Ori was observed to brightened by around 5 mag to r'=17.7. In early 2006 the star faded back to its quiescent brightness of r'~23, however, in mid-2008 it brightened yet again by ~5 mag. Our new observations, taken in early 2011, show V1647 Ori to be in an elevated photometric state with an optical brightness similar to the value found at the start of the 2003 and 2008 outbursts. Optical images taken between 2008 and 2011 suggest that the star has remained in outburst from mid 2008 to the present. H-alpha and the far-red CaII triplet lines remain in emission with H-alpha possessing a significant P Cygni profile. A self-consistent study of the accretion luminosity and rate using data taken in 2004, 2007, 2008, and 2011, indicates that when bright, V1647 Ori has values of 16+-2 Lsun and 4+-2x10^-6 Msun/yr, respectively. We support the premise that the accretion luminosity and rate both declined by a factor 2-3 during the 5mag fading in 2007. However, a significant parts of the fading was due to either variable extinction or dust reformation. We discuss these new observations in relation to previous published data and the classification schemes for young eruptive variables.