Near Infrared Spectroscopic Study of V1647 Ori

TL;DR

This study uses high-resolution infrared spectroscopy to analyze the accretion and outflow variations of V1647 Ori during its 2008 outburst, revealing correlations between luminosity, accretion rate, and disk heating.

Contribution

It provides new high-resolution spectra during the 2008 outburst and compares them with previous phases, offering insights into accretion dynamics and outflow evolution in V1647 Ori.

Findings

Br-gamma luminosity correlates with stellar brightness and accretion rate.

CO emission temperature varies with accretion activity.

Blue-shifted CO absorption lines are absent in 2008, indicating short-lived outflows.

Abstract

We present new high-resolution infrared echelle spectra of V1647 Ori, the young star that illuminates McNeil's nebula. From the start, V1647 Ori has been an enigmatic source that has defied classification, in some ways resembling eruptive stars of the FUor class and in other respects the EXor variables. V1647 Ori underwent an outburst in 2003 before fading back to its pre-outburst brightness in 2006. In 2008, it underwent a new outburst. In this paper we present high-resolution K-band and M-band spectra from the W. M. Keck Observatory that were acquired during the 2008 outburst. We compare the spectra to spectra acquired during the previous outburst and quiescent phases. We find that the luminosity and full width at half maximum power of Br-gamma increased as the star has brightened and decreased when the star faded indicating that these phases are driven by variations in the accretion rate. We also show that the temperature of the CO emission has varied with the stellar accretion rate confirming suggestions from modeling of the heating mechanisms of the inner disk (e.g. Glassgold et al. 2004). Finally we find that the lowest energy blue-shifted CO absorption lines originally reported in 2007 are no longer detected. The absence of these lines confirms the short-lived nature of the outflow launched at the start of the quiescent phase in 2006.