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  • 1
    Electronic Resource
    Electronic Resource
    Coordinated optical-EXOSAT-tenma observations of a burst from 2S1636-536 (1985)
    Springer
    Space science reviews 40 (1985), S. 249-253 
    Details
    ISSN: 1572-9672
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract During a coordinated observations of 2S1636-536 with EXOSAT, Tenma and the 1.4 metre Danish telescope at La Silla, a single burst was detected at all three observatories. The burst was bright with a peak flux of 6 × 10-8 ergs/cm 2 /s and rapid expansion of the blackbody radius. EXOSAT and Tenma agree closely in the values of blackbody radius, temperature and flux which are very similar to the three bursts recently reported by Tenma which appear to reach the Eddington flux limit at their peak. Preliminary analysis of the X-ray and optical timing data reveal that this burst is unusual in having a sharp leading edge in both X-ray and optical data and a very short X-ray-optical delay compared with those previously observed. If confirmed, this result puts significant restraints on the location of the optical reprocessing site.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00212894
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    EXOSAT observations of bursts from 2S1636-536: Burst morphology (1985)
    Springer
    Space science reviews 40 (1985), S. 263-268 
    Details
    ISSN: 1572-9672
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In two observations with the EXOSAT ME a total of 11 bursts were detected; 7 in July and 4 in May 1984. In terms of rise time and peak count rate there are only 2 kinds, those with a sharp rise and peak count rate of 500 cts/sec/detector and those with a slow rise and a peak count rate of 200 cts/sec/detector. The spectral analysis of these bursts shows a similar situation: for the sharp bright bursts the black body radius increases rapidly to 〉 20 km and the temperature lags. For the slow dim bursts the temperature rises ahead of the black body radius expansion which is small and slow. The time t 1/2 at which half the total burst energy has been released is ∼3.5 seconds for bright bursts and ∼8 seconds for dim ones. These gross differences may be related to the predominance of helium or hydrogen in the thermonuclear flash.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00212896
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    The quiescent spectrum of 2S1636-536 (1985)
    Springer
    Space science reviews 40 (1985), S. 269-273 
    Details
    ISSN: 1572-9672
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract During the EXOSAT observation of 2S1636-536 in July 1983 the quiescent flux was observed to brighten from 1.7×10 -9 ergs/cm. 2 /sec to 2.6×10-9 ergs/cm. 2 /sec, this increase being accompanied by a decrease in effective temperature. Further analysis of the spectrum reveals that the best fit is a power law with an index which increases from -1.75 to-2.1 while the source brightens; there is some evidence for an upper cut off. This spectrum is interpreted as the result of soft photons from the neutron star surface which are Comptonised in a hot plasma cloud surrounding the neutron star (neutron star corona). The increasing spectral index is seen as the result of Compton cooling of the corona as the output of quiescent flux rises in response to an increasing accretion rate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00212897
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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