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arXiv · astro-ph/0601439

Planetary nebulae with emission-line central stars

K. Gesicki·A. A. Zijlstra·A. Acker·S. K. Gorny·K. Gozdziewski·J. R. Walsh
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Abstract

The kinematic structure of a sample of planetary nebulae, consisting of 23 [WR] central stars, 21 weak emission line stars (wels) and 57 non-emission line central stars, is studied. The [WR] stars are shown to be surrounded by turbulent nebulae, a characteristic shared by some wels but almost completely absent from the non-emission line stars. The fraction of objects showing turbulence for non-emission-line stars, wels and [WR] stars is 7%, 24% and 91%, respectively. The [WR] stars show a distinct IRAS 12-micron excess, indicative of small dust grains, which is not found for wels. The [WR]-star nebulae are on average more centrally condensed than those of other stars. On the age-temperature diagram, the wels are located on tracks of both high and low stellar mass, while [WR] stars trace a narrow range of intermediate masses. Emission-line stars are not found on the cooling track. One group of wels may form a sequence wels--[WO] stars with increasing temperature. For the other groups both the wels and the [WR] stars appear to represent several, independent evolutionary tracks. We find a discontinuity in the [WR] stellar temperature distribution and suggest different evolutionary sequences above and below the temperature gap. One group of cool [WR] stars has no counterpart among any other group of PNe and may represent binary evolution. A prime factor distinguishing wels and [WR] stars appears to be stellar luminosity. We find no evidence for an increase of nebular expansion velocity with time.

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K. Gesicki, A. A. Zijlstra, A. Acker, S. K. Gorny, K. Gozdziewski, J. R. Walsh. 2006-01-20. Planetary nebulae with emission-line central stars. https://doi.org/10.1051/0004-6361%3A20054192

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