منابع مشابه
The Weak Emission Line Stars
In this paper, we study the evolution of the weak emission line central stars of planetary nebula (WELS), which are similar to the H-deficient Wolf-Rayet central stars except for systematically weaker emission lines. Our attempts at finding an evolutionary sequence for the WELS similar to what was established for Wolf-Rayet central stars, were unsuccessful. No correlation was found between any ...
متن کاملNewly Discovered Wolf-Rayet and Weak Emission-Line Central Stars of Planetary Nebulae
We present spectra of 32 previously unpublished confirmed and candidate Wolf-Rayet ([WR]) and weak emission-line (WELS) central stars of planetary nebulae (CSPNe). Eighteen stars have been discovered in the Macquarie/AAO/Strasbourg Hα (MASH) PN survey sample, and we have also uncovered 14 confirmed and candidate [WR]s and WELS among the CSPNe of previously known PNe. Spectral classifications ha...
متن کاملPlanetary nebulae with emission - line central stars
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-...
متن کاملNon - emission line young stars of intermediate mass 3
We present optical spectra of four intermediate mass candidate young stellar objects that have often been classified as Herbig Ae/Be stars. Typical Herbig Ae/Be emission features are not present in the spectra of these stars. Three of them, HD 36917, HD 36982 and HD 37062 are members of the young Orion Nebula Cluster (ONC). This association constrains their ages to be ≤ 1 Myr. The lack of appre...
متن کاملSome Common Problems and Challenges that Emission - Line Stars Present
Four examples are given of problems that arise in the study of emission-line stars, each of which deserves further quantitative study. (1) Archival slit spectra of η Car show that epochs of low excitation have occurred regularly in the 2020 day period of Damineli et al. since at least 1948. They last about 10 percent of the period. Earlier slit spectra (1899-1919) suggest that the the object wa...
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ژورنال
عنوان ژورنال: Symposium - International Astronomical Union
سال: 2003
ISSN: 0074-1809
DOI: 10.1017/s0074180900208589