Search Publications
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×…
The continuum variability of the puzzling X-ray three-period cataclysmic variable 2A 0526-328 (TV Col).
Motch, C.; Bonnet-Bidaud, J. M.; Mouchet, M.
TV Col is characterized on the basis of 120-195-nm and 190-320-nm large-aperture low-dispersion IUE spectra obtained between April 1980 and May 1982, UBV measurements obtained with the 1-m telescope at ESO in November 1979 (Motch, 1981), and JHK photometry obtained using the standard IR photometer on the 3.6-m telescope at ESO on Dec. 31, 1982. Th…
The International Ultraviolet Explorer (IUE) point spread function at low resolution.
Cassatella, A.; Barbero, J.; Benevenuti, P.
The resolution performances obtainable with IUE low resolution images are reviewed. It is shown that the spatial resolution (perpendicular to the dispersion) is strongly dependent on the telescope focussing conditions while the spectral resolution is not. After determining the telescope optimum focussing conditions, information is provided on the …
Effects of nuclear uncertainties and chemical evolution on the standard big bang nucleosynthesis
Gry, C.; Audouze, J.; Delbourgo-Salvador, P. +1 more
It is shown that consistent predictions of baryonic densities can be made only for some specific galactic-evolution models involving D and He-3: either the infall of already processed material such that D/Dp = 1/15 (where Dp is the primordial abundance of D and D is the present value) or the effect of stellar mass loss releasing D free He-3 rich m…
COS-B gamma-ray sources and interstellar gas in the first galactic quadrant. Caravane collaboration for the COS-B satellite.
Caraveo, P. A.; Bignami, G. F.; Strong, A. W. +8 more
The consequences are considered for the high-energy gamma-ray sources of the recently established correlation between the intensity above 300 MeV, and tracers of atomic and molecular gas, in the first quadrant of the Galaxy. Using a likelihood method on the complete set of COS-B data, it is shown that there are point-like gamma-ray sources which d…