X-ray view of V1647 Ori, the young star in outburst illuminating McNeil's Nebula

Abstract

McNeil's Nebula was discovered serendipitously in January 2004 in the L1630 dark cloud located in the Orion B giant molecular cloud. This reflection nebula is illuminated by V1647 Ori, a young stellar object displaying since November 2003 a dramatic optical/IR outburst, which is the origin of the rise of this fan-shaped nebula. Until recently, no X-ray satellites have had the opportunity to observe this kind of pre-main sequence eruptive object at the beginning of its accretion burst. In this respect the X-ray observations of V1647 Ori obtained in 2004 with Chandra (Kastner et al. 2004) and XMM-Newton (Grosso et al. 2005) offer new insight into pre-main sequence accretion processes. I will review these X-ray observations, which reveal a large increase of the X-ray emission compared to the pre-outburst state, and an enhanced X-ray variability. The analysis of the XMM-Newton spectra shows that about 75% of the intrinsic X-ray emission in the 0.5-8 keV energy band comes from a soft plasma component, reminiscent of the X-ray spectrum of the classical T Tauri star TW Hya, for which X-ray emission is believed to be generated by an accretion shock onto the photosphere of a low-mass star. The hard plasma component contributes about 25% of the total X-ray emission, and can be understood only in the framework of plasma heating sustained by magnetic reconnection events. A significant excess of hydrogen column density is found compared to the value derived from optical/IR observations, suggesting either that there is a real excess of gas column density - which might due to an intervening outflow unveiled from ground optical spectroscopy - or that optical/IR observations do not probe the extinction down to the star itself. I will present preliminary results of the XMM-Newton observation of V1647 Ori obtained in March 2005

Similar works

This paper was published in Hal - Université Grenoble Alpes.

Having an issue?

Is data on this page outdated, violates copyrights or anything else? Report the problem now and we will take corresponding actions after reviewing your request.