Äîêóìåíò âçÿò èç êýøà ïîèñêîâîé ìàøèíû. Àäðåñ îðèãèíàëüíîãî äîêóìåíòà : http://xray.sai.msu.ru/~mystery/html/latex/color-b.ps Äàòà èçìåíåíèÿ: Wed Sep 16 18:29:48 1998 Äàòà èíäåêñèðîâàíèÿ: Tue Oct 2 10:59:18 2012 Êîäèðîâêà: Ïîèñêîâûå ñëîâà: ï ï ï ï ï ï ï ï ï ï ï ï ï ï

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Her X­1 is one the first X­ray binary pulsar discovered by the eminent
UHURU satellite in 1972 (Tananbaum et al. 1972, Giacconi et al. 1973) and
since then remains one of the most studied accretion­driven X­ray stellar bi­
naries. The pulsar is an accretion­powered magnetized rotating (P = 1:24s )
neutron entering an eclipsing X­ray binary with a low­mass (¸ 2M fi ) optical
companion in a practically circular orbit with a period of 1.7 d. The binary orbit
inclination is i = 85\Gamma88 o , the total duration of the X­ray eclipse is around 20,000
s. The optical counterpart, HZ Her, first suggested by Liller (1972), provides a
classical example of the reflection effect when the strong orbital modulation in
optics is due to a powerful illumination of the part of normal star atmosphere
facing X­ray source (Bahcall & Bahcall 1972; Cherepashchuk et al. 1972). The
amplitude of the reflection effect strongly increases in ultraviolet and according
to many optical UBV­photometrical data is \Deltam V = 1:45; \Deltam B = 1:6; \Deltam U =
2:55.
Already very first UHURU observations of Her X­1 revealed the presence of a
long­term 34.85­d cycle. Its properties have been so interesting that practically
all specialized X­ray satellites studied it (among which Copernicus , Ariel­5,
Ariel­6 ( Davison & Fabian 1974, 1977, Ricketts et al. 1982), HEAO­1 (Gorecki
et al. 1982, Soong et al. 1987), Hakucho and TENMA (Nagase et al. 1984,
Ohashi et al. 1984), EXOSAT ( ¨
Ogelman & Tr¨umper 1988), Ginga (Deeter et
al. 1991), Astron (Sheffer et al. 1992), BATSE (Wilson et al. 1994), and RXTE
(see RXTE data are shown in Fig. 1).
The gross shape of the X­ray light curve consists of a main­on X­ray state
with a mean duration of 7 orbital periods surrounded by two off­states each 4
orbital cycles in duration, and of a secondary short­on state of smaller intensity
with a typical duration of ¸ 5:5 orbital cycles.
1