Multiple Major Outbursts from a Restless Luminous Blue Variable in NGC 3432 - Astrophysics > Solar and Stellar AstrophysicsReportar como inadecuado




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Abstract: We present new photometric and spectroscopic observations of an unusualluminous blue variable LBV in NGC 3432, covering three major outbursts inOctober 2008, April 2009 and November 2009. Previously, this star experiencedan outburst also in 2000 known as SN 2000ch. During outbursts the starreached an absolute magnitude between -12.1 and -12.8. Its spectrum showed H,He I and Fe II lines with P-Cygni profiles during and soon after the eruptivephases, while only intermediate-width lines in pure emission including He II4686A were visible during quiescence. The fast-evolving light curve soon afterthe outbursts, the quasi-modulated light curve, the peak magnitude and theoverall spectral properties are consistent with multiple episodes ofvariability of an extremely active LBV. However, the widths of the spectrallines indicate unusually high wind velocities 1500-2800 km-s, similar tothose observed in Wolf-Rayet stars. Although modulated light curves are typicalof LBVs during the S-Dor variability phase, the luminous maxima and the highfrequency of outbursts are unexpected in S-Dor variables. Such extremevariability may be associated with repeated ejection episodes during a gianteruption of an LBV. Alternatively, it may be indicative of a high level ofinstability shortly preceding the core-collapse or due to interaction with amassive, binary companion. In this context, the variable in NGC 3432 sharessome similarities with the famous stellar system HD 5980 in the SmallMagellanic Cloud, which includes an erupting LBV and an early Wolf-Rayet star.



Autor: A. Pastorello 1, M. T. Botticella 1, C. Trundle 1, S. Taubenberger 2, S. Mattila 3,4, E. Kankare 5,3, N. Elias-Rosa 6, S. Benetti

Fuente: https://arxiv.org/







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