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Optical and ultraviolet observations of the X-ray globular cluster BO 158 in M31
Cacciari, C.; Bianchi, L.; Fusi Pecci, F. +2 more
It is pointed out that the study of the globular cluster system in a galaxy is very important for understanding the formation, dynamics, and chemical evolution of that galaxy. The present investigation represents an attempt to determine the population content of the globular cluster Bo 158 in M31 through the analysis of its energy distribution in …
Ultraviolet spectra of planetary nebulae. VII. The abundance of carbon in the very low excitation nebula HE 2-131.
Seaton, M. J.; Adams, S.
Features observed in infrared spectra suggest that certain very low excitation (VLE) nebulae have low C/O abundance ratios (Cohen & Barlow 1980; Aitken & Roche 1982). Fluxes in the multiplets [O II] sun2470 and [O II] λ2326 have been measured for the VLE nebula He 2-131 = HD 138403 using lUE high-dispersion spectra. An analysis …
The detection of ultraviolet photospheric absorption in the spectra of two Wolf-rayet stars.
Fitzpatrick, E. L.
Narrow, unshifted UV absorption lines, principally of Fe v, have been detected in the spectra of two Wolf-Rayet stars, HD 93162 (WN7) and HD 193793 (WC7). Both stars are known to show upper Balmer-line absorption but exhibit no periodic Doppler shifts that might indicate the presence of a companion. If intrinsic to the Wolf-Rayet stars, these line…
A spectrophotometric analysis of the hot helium-rich white dwarf HD 149499 B.
Sion, E. M.; Wesemael, F.; Guinan, E. F.
A comprehensive analysis of the hot helium-rich white dwarf HD 149499 B is presented based on International Ultraviolet Explorer ultraviolet spectra along with available optical spectra and photometry. Line strengths, line profiles, and continuum fluxes are analyzed in terms of a new grid of hot, high-gravity stellar atmospheres of mixed compositi…
International ultraviolet explorer observations of alf Sco.
Bernat, A. P.
IUE observations of the absorption spectrum of Alpha-2 Sco B2.5 V are presented. These lines arise from matter being lost by the red supergiant primary, Alpha-1 Sco M1.5 Iab, which is passing in front of the B star. There is a factor of 30 spread in the hydrogen column densities derived from different elements on the assumption of solar abundance …
Variability and mass loss in the extreme supergiant zet01 Sco.
Bianchi, L.; Cassatella, A.; Heck, A. +1 more
It is found that the photometric variability can be characterized by a unique relationship between the half-period and the amplitude in the V band. This kind of variability differs from that characterizing the best known pulsating stars. One explanation, advanced tentatively, is that p and g modes are simultaneously excited. What is considered a m…
UV observations of TT Arietis and the magnetic rotator hypothesis
Jameson, R. F.; King, A. R.; Sherrington, M. R. +1 more
TT Arietis, one of the brightest cataclysmic variables, mv~10.2-->11.0, is usually classed as a novalike variable, but after a recent dip in brightness to mv~14.5, Krautter et al.1 suggested it to be a dwarf nova in an extended high state. Photometric light curves2-4 generally show a sinusoidal light …
International Ultraviolet Explorer observations of the R AQR jet.
Kafatos, M.; Michalitsianos, A. G.
Ultraviolet spectra were obtained with the International Ultraviolet Explorer of the newly discovered optical-radio jet feature in the symbiotic variable R Aquarii. The far-UV continuum of the jet is characterized by strong continuum which rises with decreasing wavelength in the 1200-2000 A wavelength range and is considerably different in appeara…
Active stars and systems
Rodono, M.
The most notable manifestations of stellar activity are reviewed with particular emphasis on the merging picture of solar-type activity in physical conditions different from those in the Sun. Evidence for starspots, plages and high-level coronal emissions is presented from observations covering a wide range of spectral bands: from X-ray to radio w…
Ly-alpha absorption at a high velocity in NGC1275
Boksenberg, A.; Snijders, M. A. J.; Briggs, S. A.
The results of a study of three spectra of the peculiar galaxy NGC1275 obtained with the SWP camera aboard the IUE satellite are reported and discussed. The absorption feature identified with Ly-alpha at 8200 km/s was clearly seen in all three spectra. The origin of this feature is attributed to the intervening galaxy responsible for the high velo…