X-Ray Emission From An FU Orionis Star In Early Outburst: HBC 722

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Liebhart, Armin
Gudel, Manuel
Skinner, Stephen L.
Green, Joel

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Aims. We conducted the first X-ray observations of the newly erupting FU Ori-type outburst in HBC 722 ( V2493 Cyg) with the aim to characterize its X-ray behavior and near-stellar environment during early outburst. Methods. We used data from the XMM-Newton and Chandra X-ray observatories to measure X-ray source temperatures and luminosities as well as the gas column densities along the line of sight toward the source. Results. We report a Chandra X-ray detection of HBC 722 with an X-ray luminosity of L-X approximate to 4 x 10(30) ergs s(-1). The gas column density exceeds values expected from optical extinction and standard gas-to-dust ratios. We conclude that dust-free gas masses are present around the star, such as strong winds launched from the inner disk, or massive accretion columns. A tentative detection obtained by XMM-Newton two years earlier after an initial optical peak revealed a fainter X-ray source with only weak absorption.



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Liebhart, Armin, Manuel Güdel, Stephen L. Skinner, and Joel Green. >X-ray emission from an FU Orionis star in early outburst: HBC 722.> Astronomy & Astrophysics, Vol. 570 (Oct., 2014): L11.