Search Publications
Implications of the UV observations of SN 1987A.
Panagia, N.; Fransson, C.; Grewing, M. +2 more
The implications of the UV observations of SN 1987A are discussed. The authors conclude that the UV spectrum is not a distinguishing feature between Type I and II supernovae. There is therefore no contradiction with the optical observations. Instead it is proposed that the differences in the UV properties are to be sought in the varying degree of …
A search for X-ray emission from a nearby pulsar : PSR 1929+10.
Brinkmann, W.; Kiziloglu, U.; Oegelman, H. +2 more
The authors report observations of PSR 1929+10 with the EXOSAT observatory. In the 0.04 to 2.4 keV range a 2σ upper limit of 0.5×10-3cts s-1 was obtained. This translates to a luminosity upper limit of L ≤ 2×1029erg s-1 for a power-law source with photon number index α = 1 - 3, and L ≤ 1030erg…
Long-term variability of the far-UV high velocity components in gammaCas (1978-1986).
Doazan, V.; Thomas, R. N.; Rusconi, L. +2 more
A synthesis of the authors' long term observations of γ Cas in the visual and in the far UV, combined with IUE archived spectra, shows that: (1) The occurrence of the high velocity components observed in the Si IV, C IV, and N V resonance lines exhibits a long term variability pattern, which is associated with the cyclic V/R variations of the Balm…
Alfvenic Turbulence in the Solar Wind Flow during the Approach to Comet p/ Halley
Coates, A. J.; Winningham, J. D.; Thomsen, M. F. +8 more
The Johnstone Plasma Analyser on Giotto operated almost continuously for two days before the encounter with comet Halley. Throughout this period it made observations of the proton and alpha particle distributions in the solar wind with 8 seconds time resolution. As the comet was approached, fluctuations were observed in all the primary bulk parame…
Photometry and spectroscopy of the eclipsing P Cygni star R 81 in theLarge Magellanic Cloud.
Stahl, O.; Zickgraf, F. -J.; Wolf, B.
IUE high resolution data of the LMC P Cyg star R 81 confirm that the wind characteristics of R 81 and P Cyg are very similar. Photometric monitoring from 1982 to 1986 revealed several brightness minima with a period of 74.59 days. It is concluded that R 81 is an eclipsing binary with this period. From the photometry and the period, a preliminary m…
NGC 40 : IUE observations of the nucleus.
Grewing, M.; Bianchi, L.
UV spectra of the nucleus of NGC 40 allow a derivation of an E(B-V) foreground reddening of 0.50 and a distance to the object of 980 pc; accordingly, T(eff) of 90,000 K, log L/L(solar) of 4.4, R of 0.66 R(solar), and M of 1.1 M(solar) are obtained. It is suggested that the discrepancy between the temperature determined from the UV emission of the …
The Composition and Dynamics of Cometary Ions in the Outer Coma of Comet p/ Halley
Schwenn, R.; Altwegg, K.; Balsiger, H. +15 more
During its flyby at comet Halley, the Giotto spacecraft encountered high densities of cometary ions inside approximately 200000 km from the nucleus. Their properties changed drastically as the comet was approached. We present here density profiles of solar wind alpha particles and of the major cometary ions as obtained by the IMS-HERS sensor betwe…
X-ray emission from the symbiotic system CH Cygni.
Leahy, D. A.; Taylor, A. R.
CH Cyg was observed with the EXOSAT LE1 telescope and CMA detector with 3 filters on 1985 May 24. The count rates indicate a soft X-ray spectrum with kT ≈ 0.1 keV and column density ≈4×1020 cm-2. The observed flux is ≈1.3×10-11erg cm-2s-1. An earlier upper limit obtained with the Einstein Imag…
Spectral evolution of SN 1987A in the far-ultraviolet.
Panagia, N.; Talavera, A.; Fransson, C. +4 more
Preliminary results are presented on the UV spectral evolution of SN 1987 A from IUE data obtained from February 25 to March 23, 1987. It is suggested that line blanketing, mainly from Fe II, Ni II and Ti II, variable with time, is probably responsible for the observed features. Black body fitting to the UV-optical-infrared energy distribution on …
Interstellar lines in SN 1987A observed with the IUE.
Panagia, N.; de Boer, K. S.; Grewing, M. +3 more
The SN 1987A UV-interstellar spectrum shows nine resolvable components in ionization stages ranging from neutral gas (Mg I, Si II, Fe II, etc.) to highly ionized gas (Al III, Si IV, C IV). Three components are due to gas in the Milky Way disk and halo, four are most likely due to LMC gas, two components are at velocities intermediate to those of t…