V1647 Orionis: One Year into Quiescence

TL;DR

This study presents multi-wavelength observations of V1647 Orionis one year after its outburst, revealing ongoing accretion, a young stellar classification, and potential new Herbig-Haro flow activity.

Contribution

It provides the first photospheric absorption features for V1647 Ori, constrains its spectral type, extinction, and accretion rate, and suggests the emergence of a new Herbig-Haro flow.

Findings

V1647 Ori is still actively accreting material.

Spectral type is approximately M0 with significant extinction.

Evidence of shock-excited emission indicating a new Herbig-Haro flow.

Abstract

We present new optical, near-IR, and mid-IR observations of the young eruptive variable star V1647 Orionis that went into outburst in late 2004 for approximately two years. Our observations were taken one year after the star had faded to its pre-outburst optical brightness and show that V1647Ori is still actively accreting circumstellar material. We compare and contrast these data with existing observations of the source from both pre-outburst and outburst phases. From near-IR spectroscopy we identify photospheric absorption features for the first time that allow us to constrain the classification of the young star itself. Our best fit spectral type is M0+-2 sub-classes with a visual extinction of 19+-2 magnitudes and a K-band veiling of rK~1.5+-0.2. We estimate that V1647Ori has a quiescent bolometric luminosity of ~9.5Lsun and a mass accretion rate of ~1.10^-6Msun yr^-1. Our derived mass and age, from comparison with evolutionary models, are 0.8+-0.2 Msun and ~0.5Myrs, respectively. The presence towards the star of shock excited optical [S II] and [Fe II] emission as well as near-IR H2 and [Fe II] emission perhaps suggests that a new Herbig-Haro flow is becoming visible close to the star.