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Abstract: In early 2008, the young low-mass star EX Lupi, the prototype of the EXorclass of eruptive variables, optically brightened by over five magnitudes for aperiod of 7 months. The previous time a change of such amplitude had beenobserved in EX Lup was over 50 years ago. In this Letter we present new opticaland near-IR high resolution spectroscopy of EX~Lup during the 2008 outburst. Weinvestigate the physical characteristics of the outburst both soon after itbegan and some four months later, and consider the energetics and kinematicsobserved. Emission line strengths, widths, and profiles changed significantlybetween the two observations. Also, modeling of the 2.2935 um CO overtonebandhead emission suggests that an inner gap in the circumstellar gas diskaround the star may be present and it is from the inner edge of the gas diskthat the CO overtone emission probably arises. We derive a mass accretionluminosity and rate during the extreme outburst of ~2+-0.5~Lsun and~2+-0.5x10^-7 Msun yr^-1, respectively, which suggests that this outburst wasindeed one of the strongest witnessed in EX Lup, yet not as strong as thoseobserved in FU Orionis stars.



Autor: Colin Aspin, Bo Reipurth, Gregory Herczeg, Peter Capak

Fuente: https://arxiv.org/







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