Maxwell, M. P., Rushton, M. T., Darnley, M. J., Worters, H. L., Bode, M. F., Evans, A., Eyres, S. P. S., Kouwenhoven, M. B. N., Walter, F. M. and Hassall, B. J. M.
The helium abundance in the ejecta of U Scorpii.
Monthly Notices of the Royal Astronomical Society, 419
Official URL: http://dx.doi.org/10.1111/j.1365-2966.2011.19803.x
U Scorpii (U Sco) is a recurrent nova which has been observed in outburst on 10 occasions, most recently in 2010. We present near-infrared (near-IR) and optical spectroscopy of the 2010 outburst of U Sco. The reddening of U Sco is found to be E(B − V) = 0.14 ± 0.12, consistent with previous determinations, from simultaneous optical and near-IR observations. The spectra show the evolution of the linewidths and profiles to be consistent with previous outbursts. Velocities are found to be up to 14 000 km s−1 in broad components and up to 1800 km s−1 in narrow-line components, which become visible around day 8 due to changes in the optical depth. From the spectra we derive a helium abundance of N(He)/N(H) = 0.073 ± 0.031 from the most reliable lines available; this is lower than most other estimates and indicates that the secondary is not helium-rich, as previous studies have suggested.
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