V1647 ORIONIS: Keck/Nirspec 2 MICRON Echelle Observations

TL;DR

This study uses high-resolution near-infrared spectroscopy to analyze the young eruptive star V1647 Orionis, revealing its similarities to FU Orionis objects and providing insights into its physical and evolutionary state.

Contribution

First high-resolution near-IR spectral analysis of V1647 Orionis, comparing its features to FU Orionis and EX Lupi variables to understand its nature.

Findings

V1647 Orionis resembles FU Orionis variables in quiescence.

Spectral features suggest specific physical and geometric conditions.

Implications for the star's evolutionary stage are discussed.

Abstract

We present new Keck II NIRSPEC high-spectral resolution 2 um echelle observations of the young eruptive variable star V1647 Orionis. This star went into outburst in late 2003 and faded to its pre-outburst brightness after approximately 26 months. V1647 Orionis is the illuminating star of McNeil's Nebula and is located near M 78 in the Lynds 1630 dark cloud. Our spectra have a resolving power of approximately 18,000 and allow us to study in detail the weak absorption features present on the strong near-IR veiled continuum. An analysis of the echelle orders containing Mg I (2.1066 um) and Al I (2.1099 um), Br-gamma (2.1661 um), the Na I doublet (2.206 and 2.209 um), and the CO overtone bandhead (2.2935 um) gives us considerable information on the physical and geometric characteristics of the regions producing these spectral features. We find that, at high-spectral resolution, V1647 Orionis in quiescence resembles a significant number of FU Orionis type eruptive variables and does not appear similar to the quiescent EX Lupi variables observed. This correspondence is discussed and implications for the evolutionary state of the star are considered.