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Stellar and wind properties of LMC WC4 stars. A metallicity dependence for Wolf-Rayet mass-loss rates
Hillier, D. J.; Crowther, P. A.; Fullerton, A. W. +2 more
We use ultraviolet space-based (FUSE, HST) and optical/IR ground-based (2.3 m MSSSO, NTT) spectroscopy to determine the physical parameters of six WC4-type Wolf-Rayet stars in the Large Magellanic Cloud. Stellar parameters are revised significantly relative to Gräfener et al. (\cite{Grafener1998}) based on improved observations and more sophistica…
Physical parameters of the high-mass X-ray binary 4U1700-37
Kaper, L.; Crowther, P. A.; Goodwin, S. P. +4 more
We present the results of a detailed non-LTE analysis of the ultraviolet and optical spectrum of the O6.5 Iaf+ star
Star formation and dust extinction in nearby star-forming and starburst galaxies
Buat, V.; Boselli, A.; Gavazzi, G. +1 more
We study the star formation rate and dust extinction properties of a sample of nearby star-forming galaxies as derived from Hα and UV ( ~ 2000 Å) observations and we compare them to those of a sample of starburst galaxies. The dust extinction in Hα is estimated from the Balmer decrement and the extinction in UV using the FIR to UV flux ratio or th…
Nanodiamonds around HD 97048 and Elias 1
Tielens, A. G. G. M.; Waelkens, C.; Van Kerckhoven, C.
We present an analysis of ISO-SWS observations of the Herbig Ae/Be stars HD 97048 and Elias 1. Besides the well-known family of IR emission bands at 3.3, 6.2, ``7.7'', 8.6 and 11.2 mu m these objects show strong, peculiar emission features at 3.43 and 3.53 mu m. The latter two features show pronounced substructure which is very similar in the two …
Coronal density diagnostics with Helium-like triplets: CHANDRA-LETGS observations of Algol, Capella, Procyon, epsilon Eri, alpha Cen A&B, UX Ari, AD Leo, YY Gem, and HR 1099
Schmitt, J. H. M. M.; Burwitz, V.; Raassen, A. J. J. +5 more
We present an analysis of ten cool stars (Algol, Capella, Procyon, epsilon Eri, alpha Cen A&B, UX Ari, AD Leo, YY Gem, and HR 1099) observed with the Low Energy Transmission Grating Spectrometer (LETGS) on board the Chandra X-ray Observatory. This sample contains all cools stars observed with the LETGS presently available to us with integratio…
Resolving subdwarf B stars in binaries by HST imaging
Heber, U.; Green, E. M.; Thejll, P. +2 more
The origin of subluminous B stars is still an unsolved problem in stellar evolution. Single star as well as close binary evolution scenarios have been invoked but until now have met with little success. We have carried out a small survey of spectroscopic binary candidates (19 systems consisting of an sdB star and late type companion) with the Plan…
Element abundances in cool white dwarfs. II. Ultraviolet observations of DZ white dwarfs
Wolff, B.; Koester, D.; Liebert, J.
We present a small data base of homogeneously derived photospheric element abundances of DZ white dwarfs and related objects. Our previous investigations are supplemented with the analysis of ultraviolet spectra for nine white dwarfs. Of particular interest is the detection of Lalpha absorption in van Maanen 2 and a determination of the effective …
Evidence for chemical evolution in the spectra of high redshift galaxies
Böhm, A.; Stahl, O.; Noll, S. +13 more
Using a sample of 57 VLT FORS spectra in the redshift range 1.37<z<3.40 (selected mainly from the FORS Deep Field survey) and a comparison sample with 36 IUE spectra of local (z ~ 0) starburst galaxies we derive C IV and Si IV equivalent width values and estimate metallicities of starburst galaxies as a function of redshift. Assuming that a …
Wind variability of B supergiants. IV. A survey of IUE time-series data of 11 B0 to B3 stars
Massa, D.; Prinja, R. K.; Fullerton, A. W.
We present the most suitable data sets available in the International Ultraviolet Explorer (IUE) archive for the study of time-dependent stellar winds in early B supergiants. The UV line profile variability in 11 B0 to B3 stars is analysed, compared and discussed, based on 16 separate data sets comprising over 600 homogeneously reduced high-resolu…
RU Cen and SX Cen: Two strongly depleted RV Tauri stars in binary systems. The RV Tauri photometric b phenomenon and binarity
Maas, T.; Van Winckel, H.; Waelkens, C.
We present a chemical abundance analysis on the basis of high signal-to-noise and high-resolution (lambda /Delta lambda ~ 48 000) optical spectra of two RV Tauri stars RU Cen and SX Cen. With an [Fe/H] = -1.9 and a [Zn/Fe] = +0.9 for RU Cen and a [Fe/H] = -1.1 and a [Zn/Fe] = +0.6 for SX Cen, both stars of spectroscopic class B display strong depl…