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Accretion-powered X-ray pulsars.
Nagase, Fumiaki
This paper gives an overview of X-ray pulsars powered by the accretion of matter from a companion star in a close binary system. Recent advances in studies of X-ray pulsars are reviewed, with a special focus on the results of observations by the Hakucho and Tenma satellites. Some topics revealed by the Ginga satellite in the last one-and-a-half ye…
X-ray spectrum of the BL Lacertae object PKS 2155-304.
Koyama, K.; Warwick, R. S.; Makishima, K. +4 more
The BL Lacertae object PKS 2155-304 was observed with Ginga for two days in May 1987. The 2-35 keV intensity showed a significant variability, the most rapid change being a 30 percent increase in 3 hr. The X-ray spectrum was described by a single power-law model with photon spectral index ranging between 2.7 and 2.9, but the power-law slope showed…
Analysis of the ultraviolet spectrum (2000 A to 3000 A) of Vega.
Sadakane, K.; Hirata, R.; Nishimura, M.
A high-dispersion spectrum of Vega between 2000 and 3000 A is analyzed. The continuum level is determined by searching for line-free windows, comparing the observed spectrum with a synthesized one. The damping constant of the Fe II lines arising from low-excitation levels is found to be very close to the classical value. The microturbulence parame…
Spectroscopic analysis of the suspected AM star 15 Vulpeculae.
Takeda, Y. -I.
The suspected Am star 15 Vul is characterized using the ATLAS-6 model-atmosphere program of Kurucz (1979) and spectrograms (resolution 10 and 4 A/mm) obtained with the coudespectrograph of the 1.88-m reflector at Okayama Astrophysical Observatory during September and October 1981; comparison stars are 28 And and 9 Aur. The data and calculated abun…
Radial velocity of HD 77581 (Vela X-1) in the period of 1972 - 1983.
Matsuoka, M.; Sadakane, K.; Jugaku, J.
The radial velocity of HD 77581 (Vela X-1 = 4U 0900-40) was derived from photospheric Fe Iv and Fe II lines observed by the International Ultraviolet Explorer (IUE) satellite in the period 1978-1983. No long-term variation in the radial velocity of 30 km/s was observed. It is shown that the absence of variation effectively rules out the possibilit…