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Peculiar CNO photospheric abundances in the central star of NGC 2392

Published online by Cambridge University Press:  30 August 2012

Roberto H. Méndez
Affiliation:
1Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, Hawaii 96822, USA email: [email protected], [email protected], [email protected]
Miguel A. Urbaneja
Affiliation:
1Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, Hawaii 96822, USA email: [email protected], [email protected], [email protected]
Rolf-Peter Kudritzki
Affiliation:
1Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, Hawaii 96822, USA email: [email protected], [email protected], [email protected]
Raman K. Prinja
Affiliation:
Dept. of Physics & Astronomy, University College London, Gower Street, LondonWC1E 6BT email: [email protected]
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Abstract

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Using new, high signal-to-noise CFHT ESPaDOnS visual spectrograms, and archive IUE and FUSE UV spectrograms, together with state-of-the-art non-LTE hydrodynamical model atmospheres, we have obtained accurate He, C, N, O photospheric abundance determinations in the central stars of NGC 2392, IC 4593, and NGC 6826. We compare with the corresponding nebular abundances, taken from the literature. The central star of NGC 2392 shows high He, N, and very low C, O abundances. We propose that these peculiar abundances must have originated in a common-envelope phase of interaction with a close binary companion. If we assume that the companion is more evolved than the visible central star, this offers a way of solving the old mystery of the discrepant He II Zanstra temperature of NGC 2392.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2012

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