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Paper: AG Carinae: a Luminous Blue Variable with a High Rotational Velocity
Volume: 388, Mass Loss from Stars and the Evolution of Stellar Clusters
Page: 173
Authors: Henrique Groh, J.; Damineli, A.; Hillier, D.J.
Abstract: We report the detection of broad absorptions due to Si IV λλ4088–4116 in the luminous blue variable (LBV) AG Carinae during its last hot phase (2001-2003). Our NLTE spectral analysis, with the radiative transfer code CMF-GEN, revealed the photospheric nature of these lines. Using a recently developed code to compute synthetic spectra in 2D geometry allowing for the effects of rotation, we could match the broad absorptions observed in the 2001 April spectrum with a high projected rotational velocity of 190 ± 30 kms−1. Our results show direct spectroscopic evidence, for the first time, that an LBV may rotate at a significant fraction of its break-up velocity. Thus, AGCar (and possibly other LBVs) is indeed close to the ΓΩ limit, as predicted by theoretical studies of LBVs.
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