منابع مشابه
WN stars in the LMC: Parameters and atmospheric abundances
The spectra of 18 WN stars in the Large Magellanic Cloud (LMC) are quantitatively analyzed by means of “standard” Wolf-Rayet model atmospheres, using the helium and nitrogen lines as well as the spectral energy distribution. The hydrogen abundance is also determined. Carbon is included for a subset of 4 stars. The studied sample covers all spectral subtypes (WN2... WN9) and also includes one WN...
متن کاملThe nitrogen spectra of Wolf-Rayet stars A grid of models and its application to the Galactic WN sample
Adopting the “standard model” for Wolf-Rayet atmospheres, non-LTE radiation transfer calculations are performed which account for helium and nitrogen. Grids of theoretical models are presented for the whole relevant parameter range. The WN classification criteria are employed in order to identify the subtype domains, and inconsistencies are discussed. The (almost complete) sample of known Galac...
متن کاملPopulations of WC and WN stars in Wolf-Rayet galaxies
We report the detection of WC stars in five WolfRayet (W-R) galaxies: He 2-10, NGC 3049, NGC 3125, NGC 5253 and Tol 89. The faint broad C IV λ5808 line requires sufficiently high S/N (>∼ 40) to be detected explaining the nondetection of this WC feature in previous observations. From the measurement of W-R emission lines (N III λ4640+C III λ4650, He II λ4686, and C IV λ5808), we conclude that al...
متن کاملChromospherically Active Stars in the Galactic Bulge
We present the results from the discovery and study of ∼ 3000 chromospherically active giant and subgiant stars toward the Galactic bulge. We find that these stars are predominantly RS CVn binaries with rotation periods between 10 and 100 days. We discover that the average rotational period of these stars decreases with their distance from the Galactic plane. We find that the primary stars in t...
متن کاملOn the birthrates of Galactic neutron stars
In light of the recently discovered neutron star populations we discuss the various estimates for the birthrates of these populations. We revisit the question as to whether the Galactic supernova rate can account for all of the known groups of isolated neutron stars. After reviewing the rates and population estimates we find that, if the estimates are in fact accurate, the current birthrate and...
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ژورنال
عنوان ژورنال: Astronomy & Astrophysics
سال: 2006
ISSN: 0004-6361,1432-0746
DOI: 10.1051/0004-6361:20065052