Enhanced X-ray variability from V1647 Ori, the young star in outburst illuminating McNeil's Nebula

Abstract

We report a ~38 ks X-ray observation of McNeil's Nebula obtained with XMM on 2004 April 4. V1647 Ori, the young star in outburst illuminating McNeil's Nebula, is detected with XMM and appears variable in X-rays. We investigate the hardness ratio variability and time variations of the event energy distribution with quantile analysis, and show that the large increase of the count rate from V1647 Ori observed during the second half of the observation is not associated with any large plasma temperature variations as for typical X-ray flares from young low-mass stars. X-ray spectral fitting shows that the bulk (~75%) of the intrinsic X-ray emission in the 0.5-8 keV energy band comes from a soft plasma component (0.9 keV) 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 (4.2 keV) contributes ~25% of the total X-ray emission, and can be understood only in the framework of plasma heating sustained by magnetic reconnection events. We find a hydrogen column density of NH=4.1E22 cm-2, which points out a significant excess of hydrogen column density compared to the value derived from optical/IR observations, consistent with the picture of the rise of a wind/jet unveiled from ground optical spectroscopy. The X-ray flux observed with XMM ranges from roughly the flux observed by Chandra on 2004 March 22 (~10 times greater than the pre-outburst X-ray flux) to a value two times greater than that caught by Chandra on 2004 March 7 (~200 times greater than the pre-outburst X-ray flux). We have investigated the possibility that V1647 Ori displays a periodic variation in X-ray brightness as suggested by the combined Chandra+XMM data set (abridged).

arXiv comment11 pages and 8 Figures. Accepted for publication by Astronomy & Astrophysics

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Cited by in corpus (20)

• X-Ray Spectroscopy of Stars
• X-ray Emission from T Tauri Stars and the Role of Accretion: Inferences from the XMM-Newton Extended Survey of the Taurus Molecular Cloud
• X-ray Emission from Orion Nebula Cluster Stars with Circumstellar Disks and Jets
• V1647 Orionis: One Year into Quiescence
• Optical and infrared properties of V1647 Orionis during the 2003-2006 outburst. II. Temporal evolution of the eruptive source
• V1647 Ori: The X-ray Evolution of a Pre-main Sequence Accretion Burst
• A multi-wavelength study of the young star V1118 Orionis in outburst
• X-Ray Spectral Variability During an Outburst in V1118 Ori
• V1647 Orionis: Optical Photometric and Spectroscopic Monitoring Through the 2003-2006 Outburst
• The XMM-Newton Optical Monitor Survey of the Taurus Molecular Cloud
• Evidence for T Tauri-like emission in the EXor V1118 Ori from near-IR and X-ray data
• X-raying the Beating Heart of a Newborn Star: Rotational Modulation of High-energy Radiation from V1647 Ori
• X-ray and optical bursts and flares in YSOs: results from a 5-day XMM-Newton monitoring campaign of L1551
• On the mid-IR variability of candidate eruptive variables (EXors): a comparison between Spitzer and WISE data
• Post-Outburst Phase of McNeil's Nebula (V1647 Orionis)
• A few days before the end of the 2008 extreme outburst of EX Lup : accretion shocks and a smothered stellar corona unveiled by XMM-Newton
• X-ray Production by V1647 Ori During Optical Outbursts
• Star Formation in Orion's L1630 Cloud: an Infrared and Multi-epoch X-ray Study
• Detection of a Cool, Accretion Shock-Generated X-ray Plasma in EX Lupi During the 2008 Optical Eruption
• Post-outburst radio observation of the region around McNeil's nebula (V1647 Ori)