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Soft X-ray transients in quiescence : observations of AQL X-1 and CenX-4.
van Paradijs, J.; Verbunt, F.; Arnaud, K. A. +1 more
The authors observed the soft X-ray transients Aql X-1 and Cen X-4 during quiescence with EXOSAT. For Aql X-1 they obtain a 3σ upper limit to the X-ray luminosity Lx (in the energy range between 0.5 and 4.5 keV) of <3.0×1033erg s-1, Cen X-4 was detected at Lx (0.5 - 4.5 keV) ≅ 1.5 to 4.2×1033
EXOSAT observations of X-rays from classical novae during the outburst stage.
Beuermann, K.; Krautter, J.; Oegelman, H.
Soft X-ray light curves of the classical novae Nova Muscae 1983 and Nova Vulpeculae 1984 No. 1 and No. 2 from optical maximum to about 900 days after maximum were sampled with the Exosat satellite, and the implications of the results for models of nova outbursts are considered. The observations seem best explained by the constant bolometric lumino…
EUV photometry of DA white dwarfs with EXOSAT.
Jordan, S.; Koester, D.; Brunner, H. +1 more
The authors present EXOSAT EUV observations for 9 white dwarfs of spectral type DA. These are analysed together with other observational data from the literature using theoretical model atmospheres. For 8 objects He/H abundance ratios and interstellar hydrogen column densities are obtained. The data for HZ 43 seem to contradict recent results of o…
Rotational modulation and flares on RS CVn and BY Dra-type stars. V. EXOSAT and IUE observations of a flare on EQ Pegasi.
Doyle, J. G.; Rodono, M.; Butler, C. J. +1 more
Time-trailed UV spectra and a soft X-ray lightcurve were obtained during a flare on the binary dMe star EQ Peg AB. On the basis of solar flare Mg II surface fluxes and an about 70-percent enhancement in the disk-integrated flux during the flare on EQ Peg, it is estimated that the chromospheric flare covered about 1.5 percent of the stellar surface…
Soft X-ray observations of the radio pulsar PSR 1055-52.
Brinkmann, W.; Oegelman, H.
The radio pulsar PSR 1055-52 was observed with the EXOSAT X-ray satellite for a total of 105 s. The data can be fitted best with blackbody spectra having temperatures of 5×105 ≤ T ≤ 8×105K. The obtained temperatures are consistent with recent models for the initial cooling of neutron stars.
A comparison of coronal X-ray emission observed with the Einstein andEXOSAT observatories.
Schmitt, J. H. M. M.; Monsignori-Fossi, B. C.; Pallavicini, R. +1 more
The present Einstein and Exosat observatories' star coronal X-ray emission data are subjected to a spectral analysis which employs the Raymond and Smith (1977) and Landini and Fossi (1984) computer codes to calculate X-ray emission from optically thin plasmas that are in collisional equilibrium. It is found that the derived coronal parameters depe…
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…
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…
EXO 023432-5232.3 : a new 114-minute probable AM Herculis-type binary.
Tagliaferri, G.; Beuermann, K.; Giommi, P. +1 more
A new probable AM Herculis binary was found in the course of an optical identification program of serendipitous X-ray sources detected with the EXOSAT satellite. Spectrophotometry of the 19 mag optical counterpart shows that it carries most of the hallmarks of AM Herculis binaries. The orbital period is 114.6 minutes and makes it the sixth AM Her …
EXOSAT observations of the 1983 outburst of the rapid burster : a newmode of behaviour.
Haberl, F.; Stella, L.; Parmar, A. N. +4 more
The results of three observations of the rapid burster (MXB 1730-335) made in August 1983 are reported. A new mode of behavior consisting of strong persistent emission at a level of about 5 microJY along with type I bursts recurring approximately every 80 minutes, is reported. No type II bursts were seen during this interval. The spectrum of the p…