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The visible and infrared extinction law and the gas-to-dust ratio in the Small Magellanic Cloud.
Bouchet, P.; Lequeux, J.; Prevot, L. +2 more
Photometric observations in the UBVJHK bands have been made for 23 O-B3 stars in the Small Magellanic Cloud, for which the MK spectral type and luminosity class have been determined. Also derived from these data are the extinction curve in the visible and the near-infrared. This curve is very close to the curves in the Galaxy and the Large Magella…
The hybrid spectrum of the LMC hypergiant R 126.
Stahl, O.; Leitherer, C.; Zickgraf, F. -J. +2 more
An extensive spectroscopic (1150 - 6700 Å) and photometric (UBVRIJHKLMN) study of the peculiar LMC hypergiant R126 has been carried out. The authors derive stellar parameters Teff = 22,500K, R = 72 R_sun; and Mbol = -10.5. The corresponding spectral type is B0.5 Ia+. An estimate of the initial and present mass lead…
An X-ray study of AM Herculis. I. Discovery of a new mode of soft X-ray emission.
Stella, L.; Heise, J.; King, A. R. +4 more
The discovery of a new mode of soft X-ray emission of the magnetic cataclysmic variable AM Her is reported. AM Her has been observed in June, August and September 1983 with EXOSAT in both hard (1-30 keV) and soft (40-120 A) X-rays. Hard X-rays were seen to be partially eclipsed and periodic with the white dwarf rotation period. The eclipse phases …
UV-bright stars in galactic globular clusters, their far-UV spectra and their contribution to the globular cluster luminosity.
de Boer, K. S.
Ultraviolet-bright stars in 7 galactic globular clusters have been observed with 4 - 7 Å spectral resolution between 1150 Å and 3200 Å. The UV-bright stars, which are in the post-AGB (PAGB) phase of evolution, have effective temperatures between 19,000 and 35,000K, and have luminosities of about 103.3L_sun;. They generate on average abo…
The gamma-ray deficit toward the Galactic Center.
Hermsen, W.; Bloemen, J. B. G. M.; Blitz, L. +1 more
The gamma-ray flux (E greater than 300 MeV) from the central few hundred parsecs of the Milky Way is shown to be nearly an order of magnitude smaller than the value expected from the H2 masses generally estimated to be present in the center and from the average gamma-ray emissivity measured for the disk. This result implies that in the Galactic ce…
The massive wind of S Dor.
Waters, L. B. F. M.; Stahl, O.; Leitherer, C. +4 more
Photometric and spectroscopic observations and UV spectrograms of the variable star S Dor are presented. The equipment used to obtain these data are described. The pseudophotosphere indicated by the absorption lines is examined; pulsation-like motions in the pseudophotosphere are detected. The UV data, which are characterized by Fe II and ionized …
The ejection of shells in the stellar wind of the hypergiant P Cygni (B1Ia+).
Lamers, H. J. G. L. M.; Cassatella, A.; Korevaar, P.
Radial velocity variations of six Fe II and six Fe III lines in the UV spectrum of the hypergiant star P Cygni (HD 193237) are studied in 33 high resolution IUE spectra, obtained over an interval of more than 5 yr. The Fe II lines have a stable component at -206±2 km s-1 which did not vary in velocity nor in strength in 5 yr. There are …
A study of ultraviolet spectra of zeta Aurigae/VV Cephei systems. VII. Chromospheric density distribution and wind acceleration region.
Schroeder, K. -P.
Chromospheric eclipse spectra have been obtained for three Zeta Aurigae binary systems using the International Ultraviolet Explorer (IUE) spacecraft. In order to fit average density models to the chromospheres, 3 samples of column densities (for 31 Cygni, 32 Cygni, and Zeta Aurigae K giants) were used. Wind velocities were derived assuming a conti…
The explanation of the 1400 and 1600 A features in DA white dwarfs.
Koester, D.; Weidemann, V.; Vauclair, G. +1 more
The authors present new IUE observations of 4 cool DA white dwarfs together with additional data for 8 objects from the literature. All objects show absorption features near 1400 and/or 1600 Å, which were already noted by other authors. These features are explained as due to quasi-molecular absorption of the H2 (1600 Å) resp. H2
Peculiar motions and star formation in the interacting galaxy complexMK 171 = NGC 3690+IC 694.
Lequeux, J.; Augarde, R.
Spectroscopic observations in the visible and in the far ultraviolet are combined with other existing information to interpret the properties of the exceptionally active extended star formation in Mk 171. The authors show that this system corresponds to the interaction, and probably to the direct collision, of two galaxies with a total mass of ⪉4×…