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 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 کاملShort-Term Hα Line Variations in Classical Be Stars: 59 Cyg and OT Gem
We present the optical spectroscopic study of two classical Be stars, 59 Cyg and OT Gem obtained over a period of few months in 2009. We detected a rare triple-peak Hα emission phase in 59 Cyg and a rapid decrease in the emission strength of Hα in OT Gem, which are used to understand their circumstellar disks. We find that 59 Cyg is likely to be rapid rotator, rotating at a fractional critical ...
متن کاملEvolution of emission line activity in intermediate mass young stars
We present optical spectra of 45 intermediate mass Herbig Ae/Be stars. Together with the multi-epoch spectroscopic and photometric data compiled for a large sample of these stars and ages estimated for individual stars by using pre-main sequence evolutionary tracks, we have studied the evolution of emission line activity in them. We find that, on average, the Hα emission line strength decreases...
متن کاملCandidate Hα emission and absorption line sources in the Galactic Bulge Survey
We present a catalogue of candidate Hα emission and absorption line sources and blue objects in the Galactic Bulge Survey (GBS) region. We use a point source catalogue of the GBS fields (two strips of (l × b) = (6◦ × 1◦) centred at b = 1. ◦5 above and below the Galactic Centre), covering the magnitude range 16 ≤ r′ ≤ 22.5. We utilize (r′ – i′, r′ – Hα) colour–colour diagrams to select Hα emissi...
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ژورنال
عنوان ژورنال: Symposium - International Astronomical Union
سال: 1991
ISSN: 0074-1809
DOI: 10.1017/s0074180900046106