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arXiv · 1112.2925

Rotational properties of single and wide binary subdwarf B stars

S. Geier·U. Heber·H. Edelmann·R. Napiwotzki·L. Morales-Rueda
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Abstract

We measured projected rotational velocities of more than a hundred apparently single sdBs. A comparison is made with sdB stars in binary systems with orbits so wide, that tidal interaction becomes negligible. All of these stars are slow rotators (vsini<10 km/s) with EC 22081-1916 being the only exception. This single star has the highest projected rotational velocity ever measured for an sdB (vsini=163 km/s) and might have been formed by a merger event. The merger of a red-giant core and a low-mass, main-sequence star or substellar object during a common envelope phase fits particularly well with observations. The implications of our results for hot subdwarf formation are briefly discussed.

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S. Geier, U. Heber, H. Edelmann, R. Napiwotzki, L. Morales-Rueda. 2011-12-13. Rotational properties of single and wide binary subdwarf B stars. https://arxiv.org/abs/1112.2925

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