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Rotational modulation and flares on RS CVn and BY DRA systems. VII. simultaneous X-ray, radio and optical data for the dMe star YZ CMi on 4/5 March 1985.
Doyle, J. G.; Butler, C. J.; van den Oord, G. H. J. +1 more
Broad-band photometric observations of YZ CMi show a 1.2mag U-band flare at 19:55 UT on 4 March 1985, however, simultaneous X-ray observations from EXOSAT show no detectable increase. Two possible explanations for the lack of an X-ray flare may be i) a flare occurring low in the chromosphere, where the chromosphere may not have been coupled to the…
An EXOSAT observation of an X-ray flare and quiescent emission from the RS CVn binary sigma2 CrB.
Mewe, R.; Brinkman, A. C.; van den Oord, G. H. J.
The RS CVn binary sigma2 Coronae Borealis was observed with medium-energy and low-energy detectors and the transmission grating spectrometer aboard EXOSAT, and a strong X-ray flare rising within about five minutes and lasting more than two hours was detected. The temperature rises steeply within three minutes from 19 MK to a value well above 70 MK…
Stellar coronae with EXOSAT : broad band spectroscopy of nearby coronal sources.
Schmitt, J. H. M. M.; Monsignori-Fossi, B. C.; Landini, M. +1 more
Broad-band observations of stellar coronae obtained with the Low Energy experiment on board the Exosat satellite are presented, together with a technique for the analysis of Exosat low-energy data. The limitations of filter spectroscopy with Exosat are discussed. Specific relationships are provided for extracting physical quantities (temperature, …
Co-ordinated VLA and EXOSAT observations of the flrae stars UV Ceti, EQ Pegasi, YZ Canis Minoris and AD Leonis.
Pallavicini, R.; Kundu, M. R.; White, S. M. +1 more
The authors have observed four flare stars (UV Cet, EQ Peg, YZ CMi and AD Leo) simultaneously with the VLA and the EXOSAT satellite over continuous periods of 7 - 10 h. This is the first time that flare stars were observed simultaneously in X-rays and at microwave frequencies with high sensitivity instrumentation. All stars were detected both at t…
Time variability in the X-ray emission of dM stars observed by EXOSAT.
Schmitt, J. H. M. M.; Pasquini, L.; Collura, A.
The authors studied the variability in the X-ray emission of 13 dMe stars observed with the LE+CMA onboard EXOSAT. The basic aim of this paper is to search for frequently occurring impulsive events with small energy releases in an effort to find out whether the "quiescent" X-ray emission from dM stars is really quiescent. The authors do not find, …
A correlation between Balmer and soft X-ray emission from stellar andsolar flares.
Foing, B. H.; Rodono, M.; Butler, C. J.
Simultaneous optical spectroscopy and X-ray monitoring of stellar and solar flares shows that a well-defined linear correlation exists between the integrated Hγ and soft X-ray flux that extends over four orders of magnitude. The existence of this relationship implies a direct proportionality between the emission from the cooler and denser regions …
New constraints on neutron star models of gamma-ray bursts. I. EXOSATobservations of two gamma-ray burst error boxes.
Hurley, K.; Boer, M.; Niel, M. +13 more
Two EXOSAT observations of gamma-ray burst error boxes and their possibly associated optical transients are discussed. No point source was detected in either box. A comparison with Einstein data (Pizzichini et al., 1986) is made for one of them (November 19, 1978). The data are interpreted in the framework of neutron star models for gamma-ray burs…
Rotational modulation and flares on RS CVn and BY DRA systems. VIII. Simultaneous EXOSAT and H alpha observations of a flare on the dMe star GL 644 AB (Wolf 630) on 24/25 August 1985.
Tagliaferri, G.; de La Reza, R.; White, N. E. +5 more
A large flare was detected simultaneously in X-rays and H-alpha on the visual binary Gl 644 AB at about 00:15 UT on August 25, 1985. The flare was detected with both the low (0.05-2 keV) and medium energy (2-7 keV) experiments onboard Exosat, with the flare rise time being similar in both the low and medium energy ranges, although in the low energ…
A 23h EXOSAT observation of the X-ray pulsar 1E 2259+586 and the associated supernova remnant G 109.1-1.0
Coe, M. J.; Dennerl, K.; Hanson, C. G. +1 more
The X-ray pulsar, 1E 2259+586, and the associated supernova remnant, G 109.1-1.0 were observed with the EXOSAT on 1984 December 1/2. The pulse period at this epoch was 6.978720±0.000006(1σ) s, indicating that between 1981 and 1984 the pulsar was spinning down with an average secular rate of change of the spin period given by P/P = +[3.3±0.2]×10
The recurrence behaviour of X-ray bursts from 4U/MXB 1735-44.
van Paradijs, J.; Lewin, W. H. G.; Sztajno, M. +2 more
During about 80 h of uninterrupted observations of the X-ray burst source 4 U/MXB 1735-44, made in August 1985 with Exosat, five bursts were observed. The bursts occur at irregular intervals, ranging between 30 min and 36 h. The burst sizes do not scale with the intervals preceding the bursts; in particular the energy in a burst which occurred aft…