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Accretion disk in the high-redshift quasar HS 1700+6416.
Siemiginowska, A.; Dobrzycki, A.
We apply the standard accretion disk model to reproduce the EUV spectrum of the high-redshift (z = 2.72) quasar HS 1700+6416. We find a satisfactory fit to the observed spectrum. The contribution of the accretion disk to the continuum emission in the soft X-ray spectral region may be significant.
COS-B: The highlights
Bennett, Kevin
The COS-B satellite operated from August 1975 until April 1982 during which time an extensive survey of the Galaxy was made in the energy range 50 MeV to 5 Gev. The Caravane Collaboration built the gamma-ray telescope and performed the bulk of the scientific data reduction. Since the data are now available to the Astrophysics community at large, s…
The nature of the hot subdwarf SB 744.
Unglaub, K.; Bues, I.
Various spectra in the visual wavelength range, one low-resolution ultraviolet spectrum, and color measurements in the red region have been taken to clarify the nature of the hot subdwarf SB 744. The colors and weak metallic lines as well as a G-band (CH) in the visual spectra indicate the existence of a cool companion, whereas the hydrogen and he…
Spectro-imagery of small diameter galaxies. I. Markarian 600 = MCG 1-08-008.
Figon, P.; Vanderriest, C.; Augarde, R. +1 more
The blue dwarf irregular galaxy Markarian 600 was observed by classical (slit) spectrography as well as bidimensional (fibre optics) spectrography. This object is found to be metal-deficient (about 1/8 solar) with an underabundant young stellar content. Two knots of gas ionized by hot stars (T_eff_ ~/- 50 000 K) are imbedded in a faint red envelop…
The Hot DOA1 Degenerate HZ 21: A Search for Circumstellar/Photospheric Metals and Peculiar Absorption at He II
Sion, E. M.; Vauclair, G.; Liebert, J. +2 more
A high-resolution IUE spectrum of the hot DO1 degenerate HZ 21 was obtained by combining US1 + European 2 low-background observing shifts. The SWP image reveals a rich spectrum of interstellar absorption lines with an average velocity in the line of sight to HZ 21 of -30 km/s. However, there is no clear evidence of any highly or lowly ionized meta…
The Problem of the HIPPARCOS Reference Frame
Lattanzi, M. G.; Bucciarelli, B.; Bernacca, P. L.
The basic principles of the realization of a fundamental optical reference frame by using space platforms are outlined in the light of the first of such astrometry projects, i.e., the HIPPARCOS mission of the European Space Agency. The available adaptations of these principles, expected to lead to a HIPPARCOS catalog of more than 100,000 star posi…
Overview of recent analysis of the energetic particle observations recorded in Situ by the EPONA instrument on the Giotto Mission to Comet Halley
Neubauer, F. M.; Daly, P.; McKenna-Lawlor, S. M. P. +4 more
Highlights of recent results obtained through analyzing data recorded by the energetic particles experiment EPONA on the Giotto Mission to Comet Halley (March 12-15, 1986) from ∼7 × 10 6 km upstream of the bow shock (inbound) to ∼6 × 10 6 km upstream of the bow shock (outbound) are presented. The identities of the ions record…
The Ultraviolet Spectrum of the Be-Star 88-HERCULIS
Danezis, E.; Theodossiou, E.
In this paper, we give a detailed list and analysis of line identifications of the UV spectrum of the Be star 88 Her in the wavelength range λλ1958–3002 Å recorded in 1984, 23 May with the International Ultraviolet Explorer (IUE). The spectrum is crowded by shell absorptions lines, mostly those of singly ionized iron peak elements. The detailed an…
Search for chromospheric MgII emission in Ap-type stars.
Seggewiss, W.
Observations of the Mg II h and k line resonance doublet in the spectra of 10 of the latest Ap-type stars show no sign of emission cores in the broad absorption lines. Thus, the Mg II lines give no evidence for chromospheric activity in peculiar A-type stars; the present observations sharpen the boarder between active and non-active stars. This fa…
Multifrequency Behaviour of the Dwarf Nova Ss-Cygni
Rossi, C.; Gaudenzi, S.; Giovannelli, F. +3 more
Several years of coordinated multifrequency observations of the dwarf nova SS Cygni have been performed in order to study the accretion behaviour of this system in particular, and in general to clarify this crucial problem for the cataclysmic variables. From IUE measurements, together with those from optical and IR ground based telescopes, we have…