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GX 339-4 : EXOSAT observations in the off and soft states.
Chiappetti, L.; Motch, C.; Ilovaisky, S. A. +1 more
Exosat observations of the highly variable low-mass X-ray binary GX 339-4, obtained with the low-energy telescope and channel-multiplier array in the off state on Apr. 25, 1985, and with the medium-energy Ar proportional counters and collimator array in the off state in Apr. 29, 1985, and in the soft state on May 7, 1984, are reported. The data ar…
Spectrophotometry of the eclipsing dwarf nova V2051 Ophiuchi.
Watts, D. J.; Bailey, J.; Hill, P. W. +3 more
A detailed phase-dependent spectroscopic study of the eclipsing dwarf nova V2051 Oph is reported. The spectroscopic observations were carried out in the optical and UV wavelengths using the 3.9-meter Anglo-Australian Telescope (AAT) International Ultraviolet Explorer (IUE) spacecraft. The optical spectrum shows strong Balmer emission, as well as w…
The ultraviolet to infrared continuum of ten narrow emission line active galaxies.
Boisson, C.; Durret, F.
The overall continuum spectra of 10 narrow line active galaxies are presented based on IR ground-based and IRAS photometry, long slit optical spectrophotometry and UV spectroscopy obtained with the IUE. Nonstellar components found include a nonthermal power law continuum in the optical, a thermal UV component from an accretion disk, Balmer continu…
NLTE-analysis of the sdO star ROB 162 in the globular cluster NGC 6397.
Heber, U.; Kudritzki, R. P.
A high-resolution visual blue spectrum of the subluminous O star ROB 162 in the globular cluster NGC 6397 has been analysed for its atmospheric parameters by means of NLTE model atmospheres. The effective temperature Teff = 51000±2000K, the gravity log g = 4.5±0.2 and a normal helium mass fraction (Y = 0.28 (+0.04, -0.06)) resulted. Spe…
Bootstrap sampling - Applications in gamma-ray astronomy
Mayer-Hasselwander, H.; Simpson, G.
Techniques for using bootstrap sampling (BS) methods to analyze cosmic gamma ray data are described. Sophisticated statistical techniques are required for gamma ray analyses because of the rarity of available data, i.e., only about 200,000 photons in the energy range 50-5000 MeV have been recorded to date. BS consists basically of randomly samplin…
Abundances in the planetary nebula BD +30 3639.
Pottasch, S. R.; Pwa, T. H.; Mo, J. E.
High resolution IUE spectra of the low excitation nebula BD +30°3639 show absorption lines of nebular material and of the intervening ISM. With the method described in Pwa et al. (1984) ionic abundances were derived for Mg0, Mn+, Fe+, Zn+ (all for the first time in a PN) and for Mg+, Al+<…
The outer atmosphere of the carbon star TX Piscium.
Eriksson, K.; Gustafsson, B.; Olofsson, H. +5 more
A high-resolution LWP IUE spectrum of the bright N-type carbon star TX Psc demonstrates that the Mg II h and k emission profiles are strongly affected by absorption from Mg II, Mn I, probably Fe I, and possibly from molecules. The indication that the absorbing matter has a column density of not less than 10 to the 20th H atoms or molecules per sq …
EXOSAT detection of an X-ray flare from the solar type star pi 1 UMa.
Piro, L.; Landini, M.; Pallavicini, R. +1 more
An X-ray flare has been detected on the G0 dwarf star π1UMa using the European satellite EXOSAT. With the exception of the Sun, this is the first time that an X-ray flare has been observed in a normal solar-type star, which is not a member of a binary system and is not a classical flare star. As a member of the Ursa Major Cluster, π
Metal abundances in helium-rich white dwarf atmospheres.
Koester, D.; Weidemann, V.; Zeidler-K. T., E. -M.
IUE observations of L745-46A, L119-34 and Ross 640 reveal the presence of Si, Fe, C, and very strong Mg II lines. These spectra, together with optical observations of white dwarfs with Ca II lines (type DZ) are analyzed within a network of model atmospheres with varying H/He, C/He and metals/He ratios. The influence of non-negligible H content (el…
The narrow line active galaxies NGC 3081 and NGC 4507 : from the infrared to the UV.
Durret, F.; Bergeron, J.
The authors present optical data on NGC 3081 and NGC 4507, acquired as part of a long slit spectroscopic search for extended ionized line emission around active galactic nuclei. For both AGNs an extended ionized region surrounding the nucleus was detected together with ionized gas in the ring of NGC 3081 and in the spiral arms of NGC 4507. The aut…