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A catalogue of QSOs and link stars for the HST link of the HIPPARCOS reference frame.
White, G. L.; Hemenway, P. D.; Argue, A. N. +6 more
A list of bright (less than 17 mag) southern QSOs and bright (less than 11 mag) stars that may be suitable for the Hubble Space Telescope link between the Hipparcos astrometric reference frame and the VLBI extragalactic frame is presented. The QSOs have been selected from various lists of radio objects and identifications. The stars have been sele…
Pulsed gamma-rays from PSR 1951 + 32
Li, Ti-Pei; Wu, Mei; Ma, Yu-Qian +1 more
In a previous paper [1] we obtained statistically significant evidence for a 39-ms period in the COS-B data of 30-5000 MeV gamma rays in the direction of PSR 1951 + 32. Most of the gamma photons from PSR 1951 + 32 are pulsed and concentrated in a narrow interval of phase. We have examined the partical distribution of gamma ray intensity in the reg…
Ultraviolet Flux Variation of Epsilon Aurigae
Kang, Young Woon
The eighteen ultraviolet light curves of Epsilon Aurigae have been plotted using the integrated fluxes reduced from the 233 IUE low dispersion spectra taken between 1978 and 1986. The times of contacts and depth of eclipse have been determined from the light curves at the wavelength from 2550 Å to 3050 Å. The UV light curves show two brightenings …
HD 51956: A Supergiant in an Interacting Binary
Parsons, Sidney B.; Ake, Thomas B.
IUE ultraviolet spectral observations reveal that the F supergiant HD 51956 contains a hot companion star partially obscured by warm plasma. Variable absorption features are analogous to those in the strongly interacting system HD 207739. The F type component is apparently transferring matter to a subluminous B type star which originally was the p…
Ultraviolet to near-infrared continuum flux distribution in the active binary RS canum venaticorum
Fabregat, J.; Reglero, V.; Gimenez, A.
We present multifrequency observations of the active binary RS CVn. Ultraviolet observations were obtained from the IUE data bank. Optical observations were made at the Observatorio del Roque de los Muchachos (La Palma), while the infrared observations were obtained at the Observatorio del Teide (Tenerife). The continuum of RS CVn shows that both …
Asymmetric winds in be stars
de Freitas Pacheco, J. A.; de Araujo, F. X.
The CIV and SiIV resonance doublets of 43 Be stars are investigated. Measurements of the equivalent widths seem to reveal a correlation between the strenght of the lines and the projected rotational velocity (v sini). it is discussed whether this result indicate that the wind region is not spherically symmetric.
Cygnus X-3: The recent X-ray period measurements and gamma-ray astronomy
van der Klis, M.
Our knowledge about the nature of Cyg X-3 is briefly reviewed, with particular emphasis on the lack of observational basis for some common assumptions about the object. Some consequences for gamma-ray astronomy are considered of the X-ray period measurements with EXOSAT, which indicate the presence of a large second period-derivative. If the orbit…
The Structure of the Broad Line Region in FAIRALL:9
Zheng, Wei; O'Brien, Paul T.
We find that the profile changes observed for the UV emission lines Lα,CIV λ1549, and MgIII λ2798, in the Seyfert 1 galaxy Fairall 9 occur mainly near the line centre for Lα andCIV and in the wings for MgIII. These results indicate that the broad line region (BLR) has a complex structure, possibly with non-spherical components.
Searches in the COS-B Gamma Ray Data-Base for Pulsations from PSR 1951+32
D'Amico, N.; Bennett, K.; Buccheri, R. +3 more
TeV and MeV gamma-rays from binary systems
Carollo, C. M.; Raubenheimer, B. C.; Buccheri, R. +4 more
We report the third consecutive detection of Vela X-1 as a source of VHE gamma-rays ( Eγ > 1 TeV) with a 99.92 % significance. The pulsed emission shows a broad sinusoidal light curve at a period similar to the X-ray value, with a large negative period derivative over the 60 days of observation. We also report our observations on Cen…