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IUE observations of the bright Herbig AE star HD 104237.
Talavera, A.; Catala, C.; The, P. S. +4 more
IUE observations are noted to indicate that HD 104237 exhibits the same UV, visible, and IR spectral properties as the Herbig Ae stars AB Aur and HR 5999. It is accordingly concluded that HD 104237 is a 2.1 solar-mass Herbig AE star. With respect to HR 5999, the chromospheric and transition region emission-line flux of HD 104237 is sufficiently la…
Scattering of X-rays on the winds of supergiant X-ray binaries.
Haberl, F.
Monte-Carlo simulations of Thomson scattering of X-rays in the stellar wind of OB stars in supergiant X-ray binaries show that at least part of the low-energy excess seen in the X-ray spectra during phases of high absorption can be explained by scattering of X-rays around a dense region in the wind obscuring the direct radiation. In the case of 4U…
Discovery of a new bright southern QSO.
Wisotzki, L.; Wamstecker, W.; Reimers, D. L.
WithIn the newly started Hamburg/ESO survey for bright southern quasars the low-redshift QSO HE 1029-1401 (z = 0.086) was found by automated search on objective prism plates and subsequently confirmed by slit spectroscopy. With v = 13.86 it is among the three brightest QSOs in the sky and the brightest ever found by optical selection. Broad band o…
NGC 6868 : a merger with dust and extended Ly-alpha emission.
Norgaard-Nielsen, H. U.; Jorgensen, H. E.; Hansen, L.
We present IUE observations of the E2 galaxy NGC 6868 showing extended Lyα emission and a weak UV continuum source which also seems extended. Along the lines of sight to the Lyα clouds the column density of neutral hydrogen must be extremely low. Ground based CCD imaging shows the distribution of interstellar dust and optical emission line gas. Ou…
Stellar winds and UV extinction of OB stars in M 33 and M 31.
Bianchi, L.; Hutchings, J. B.; Massey, P.
We report on the continued study of the most luminous hot stars in galaxies of the Local Group, with the aim of studying their spectroscopic and wind characteristics, and comparing them with similar Milky Way stars. We present results from groundbased optical and IUE UV observations of five bright blue stars in M33 and four in M31. Four of the M33…
The UV variability of the intermediate polars TW Pictoris (H 0534-581) and TX Columbae (1H 0542-407).
Bonnet-Bidaud, J. M.; Buckley, D. A. H.; Mouchet, M. +1 more
UV observations of two X-ray sources suggested to be nonsynchronous magnetic cataclysmic binaries (TW Pic and TX Col) are reported. Each source was observed at different epochs with simultaneous optical photometry in one case (TW Pic). The UV spectrum of both sources is typical of intermediate polars, showing a blue continuum with strong N V, C IV…
EXOSAT observations of the X-ray burst source 4U 1702-42.
van Paradijs, J.; van der Klis, M.; Lewin, W. H. G. +2 more
The two Exosat observations of 4U 1702 - 42 are reported. In one of them three bursts are detected. The bursts and the spectral and fast-temporal behavior of the persistent emission are analyzed. It is concluded that 4U 1702 - 42 is an atoll source, which was in the banana state when the bursts were present. The characteristics of the burst are si…
The nature of the F STR lambda 4077 stars. IV. Search for white dwarfs around barium dwarfs.
Lanz, T.; North, P.
The energy distribution of three stars classified as F str 4077-A by Bidelman has been observed in the ultraviolet with the IUE satellite. Although the stars examined have the same kind of abundance anomalies as the Ba giants and Bond's CH subgiants (i.e. an overabundance of s-process elements), no UV excess related with the presence of the expect…
The luminosity of the B2 hypergiant HD 80077.
de Jager, C.; Nieuwenhuijzen, H.; Carpay, J.
The extremely bright and relatively stable hypergiant HD 80077 is an enigmatic object. Since the star is assumed to have a luminosity of 2 x 10 exp 6, considerable variability and a large mass loss rate would be expected. However, its mass loss rate of (5 +10/-3) x 10 exp -6 solar mass/yr and its variability are very low with respect to its lumino…
Quasr link conditions for Hipparcos.
Ducourant, C.; Brosche, P.; Geffert, M. +2 more
Fictitious proper motions of quasars and of their surrounding stars have been determined based on plates with epoch differences of up to 90 yrs. From the fact that the true proper motions of the quasar are vanishingly small, we obtain conditions for the extragalactic calibration of the preliminary Hipparcos system. We present results for the field…