摘要:

Highlights of observational results obtained by ‘‘Hakucho’’ and ‘‘Tenma’’ and thereby raised questions are reviewed on transient phenomena and time variability of x‐ray sources.

ISSN:0094-243X    

DOI:10.1063/1.34511

出版商:AIP    

年代:1984

数据来源: AIP

ISSN:0094-243X    

DOI:10.1063/1.34513

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

The pulse periods of eight pulsars Her X‐1, Cen X‐3, Vela X‐1, A0535+26, GX301‐2, 4U1626‐67, 4U1538‐52, and OA01657‐415, have been measured with HAKUCHO and TENMA satellites between March 1979 and July 1983. Not only the wind‐fed X‐ray pulsas such as Vela X‐1, GX301‐2 and A0535‐26, but also Her X‐1 and Cen X‐3, which are considered to be disk‐fed pulsars, exhibit a remarkable change in the spin‐up rate.

ISSN:0094-243X    

DOI:10.1063/1.34514

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

We have discovered a 7.1 h period and eclipses in the X‐ray emission from MXB 1659‐29. MXB 1659‐29 is the first burst source to show persistent, regular eclipses. Irregular variability is observed during approximately 25% of the cycle (∼1.5 hours) immediately preceding the eclipse, which is only 15 minutes in duration. We derive limits to the mass of the binary companion to the X‐ray emitting neutron star, and argue that the companion is less massive than the canonical prediction for Roche lobe filling main sequence stars.

ISSN:0094-243X    

DOI:10.1063/1.34515

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

The orbital period change due to unstable binary orbit has been examined for 6 binary x‐ray pulsars. It is shown that the orbital period decrease in Cen X‐3 is interpreted by this mechanism. SMCX‐1 is the next candidate for the unstable orbit, but more observations are necessary to reach the conclusion.

ISSN:0094-243X    

DOI:10.1063/1.34516

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

The pulse‐timing data of A0535+25, obtained by the Hakucho satellite in October 1980 is analyzed taking into consideration other observations. The results show that a considerable fraction of the observed period change is intrinsic.

ISSN:0094-243X    

DOI:10.1063/1.34517

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

The 13‐70 kev emission from the 0.7s X‐ray pulsar SMC X‐1 was monitored by the UCSD/MIT instrument aboard HEAO‐1 during three ‘‘80‐day epochs in 1977 and 1978. The X‐ray flux wandered slowly between a maximum value and unobservably small levels with a rough time scale of 60 days. This pattern resembles, but is less regular than, the ‘‘1 month cycles of Her X‐1 and LMC X‐4, which are attributed to regular occulation by a tilted precessing accretion disk. Alternatively, the data also resemble band‐limited red noise, which then would imply a highly variable accretion flow. There is no evidence for cyclotron lines in the spectrum.

ISSN:0094-243X    

DOI:10.1063/1.34518

出版商:AIP    

年代:1984

数据来源: AIP

ISSN:0094-243X    

DOI:10.1063/1.34519

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

A steady hard X‐ray emission between 20‐100 keV was observed from the 104 sec pulsar 0535+26 during the quiescent phase of transient activity. The present observations corespond to the binary phase of 0.7 taking 110d as the binary period. The observed flux was comparable to ∼20 milli‐crab and a power law spectrum with spectral index &agr;∼1.2 fits the data, and significantly differs from the observed spectrum during the outburst.

ISSN:0094-243X    

DOI:10.1063/1.34520

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

We review current models of X‐ray pulsars in the light of our observational knowledge. The physics of the accretion column and the polar cap are discussed, and the main physical processes described, emphasizing the peculiarities introduced by the strong magnetic field. Radiative transfer methods adapted to these extreme conditions are outlined. We then discuss recent calculations on the self‐consistent structure of the X‐ray emission region, aimed at providing realistic theoretical spectra and pulse shapes.

ISSN:0094-243X    

DOI:10.1063/1.34521

出版商:AIP    

年代:1984

数据来源: AIP