Search Publications
Identification lists of the far UV spectra of 7 solar chemical composition main sequence stars in the spectral range B2-B9.5.
Pasian, F.; Castelli, F.; Morossi, C. +2 more
The authors present the identification lists for the far UV spectrum of 7 main-sequence stars with solar chemical composition, covering the spectral type range B2 - B9.5, to be used for comparison purposes in the analysis of UV spectra. The lists have been obtained by means of an automatic procedure developed by the authors consisting of the autom…
Rapid emission-line variations in the UV spectrum of the Wolf-Rayet system HD 90657.
Koenigsberger, G.; Auer, L. H.
The authors report IUE observations of the Wolf-Rayet binary system HD 90657 which indicate that a major change in the properties of the W-R wind occurred on time scales of less than 90 minutes. These are very rapid variations when compared to those resulting from atmospheric eclipse effects, which are also observed in this system. The rapid chang…
On the possibility of interpretation of MgII profiles in hybrid stars.
Jasinski, M.
Semiempirical models of expanding chromospheres have been constructed for five hybrid stars by fitting of the computed Mg II profiles to the observational data. The mass loss rates obtained from these models range from 1.34×10-9 to 3.14×10-7M_sun;/year. On the basis of energetic considerations a possible mechanism acceleratin…
Observations of X-ray emission from the RS CVn binary HD 155555 and the detection of a nearby serendipitous source.
Barstow, M. A.
Results of the EXOSAT observation of the RS CVn binary HD 155555 are reported. A new source EXO 171224-6653.9 has been discovered, lying only 40 arcsec away from HD 155555. Broad band X-ray photometry allows constraints to be placed on the plasma temperature (5×105 - 1.3×106K) and emission measure (4.5×1051 - 8×10<…
Ultraviolet spectra of field horizontal-branch A type stars.
Huenemoerder, D. P.; Philip, A. G. Davis; Hayes, D. S.
The spectra of four FHB stars have been obtained at about 5 Å resolution between λ1200 and λ1900 with the International Ultraviolet Explorer (IUE). The intensity distributions of three of the stars match that of the "FHB distribution" in Huenemoerder et al. (1984). The coolest star of the four, HD 2857, has an ultraviolet distribution that drops o…
X-Ray and Optical Observations of the X-Ray Source EX:0020528+1454.8
Richter, G. A.; Hudec, R.; Goetz, W. +7 more
We present preliminary results of the EXOSAT X-ray observations and quasisimultaneous and simultaneous optical photometry of the X-ray source EX0020528+1454.8=1E0205+149 found independently as an serendipitous source both with Einstein and EXOSAT satellites. The optical counterpart is a pair of dMe stars. Our results indicate that the object is va…
Image restoration using the point spread function of the Halley Multicolour Camera
Keller, H. U.; Kramm, J. R.; Moehring, W.
The optical resolution of the Halley Multicolour Camera (HMC) is limited by its finite aperture, by minute mechanical degradations within the instrument, and by the high speed time delay and integration (TDI) illumination method adapted to the spin of the spacecraft. The sum of all implies a visible loss of image sharpness. The smearing effect has…
Possible H2 emission in Comet Bradfield
Krishna Swamy, K. S.; Tarafdar, S. P.
The authors have identified tentatively an observed feature at 1600 Å in comet Bradfield with H2 fluorescence emission.
Doppler effect as the cause of X-ray flux modulation from an ultra-short period binary.
Postnov, K. A.; Shakura, N. I.
Exosat observations of 4U 1820-30 are examined. It is found that the Doppler effect may be responsible for the modulation of the X-ray flux from this binary. The modulation amplitude is determined by the mass function of the system.
X-Ray and Ultraviolet Observations of Ag-Draconis during Quiescence and Outburst
Piro, L.; Córdova, F. A.; Friedjung, M. +3 more
We describe the first X-ray monitoring of a symbiotic star during phases of enhanced activity. AG Dra is a Pop II object with a composite spectrum, characterized by a cool K-type component, prominent high ionization emission lines and a strong UV continuum which is attributed to a hot dwarf companion. Periodic variability of the UV radiation durin…