Search Publications
CCD astrometry of visual binaries. II. Differential measurements of northern double stars.
Sinachopoulos, D.; Seggewiss, W.
Separations and position angles of 148 visual multiple systems were measured by means of a CCD detector attached to the Calar Alto 1.23-m telescope. The program stars are candidates for the Hipparcos Input Catalog.
High-Velocity Interstellar Gas in the Lines of Sight to the Wolf-Rayet Stars HD 97152 and HD 96548
Nichols-Bohlin, Joy; Fesen, Robert A.
The interstellar medium was studied in the direction to the WR stars HD 96548 and HD 97152, and the results are reported. New observational data on the UV spectra of several field stars near both these WR stars are presented. The high-velocity gas seen in the spectra of these stars suggests that the detected expanding interstellar gas structure co…
The EXOSAT low energy imaging telescopes and transmission grating spectrometers, calibration and in-flight verification.
Brinkman, A. C.; Paerels, F. B. S.; de Korte, P. A. J. +2 more
The calibrations of the Low Energy Imaging Telescope and Transmission Grating Spectrometers on the European X-ray Observatory Satellite Exosat are presented. The final calibration is based primarily on calibration data obtained in the laboratory; verifications and checks of these calibrations with the aid of suitable astrophysical data obtained wi…
Fe - MG II K line fluorescence in K giant and bright giant stars.
Harper, G. M.
Emission lines of Fe I from the multiplet uv44 are observed at 2823.28A and 2843.98A in late-type giant and bright giant stars. It has been recognized for some time that these lines can be excited by Mg II k line radiation in the transition at 2795.54A. The first radiative transfer calculations to account for the strength of the Fe I lines Iota Au…
Activity in late-type stars. VII. Chromospheric and transition region line fluxes in 2 dM and dM(e) stars.
Doyle, J. G.; Byrne, P. B.
Ultraviolet spectra of the two dM stars Gl380 and Gl411 and the dM(e) Gl900 are presented. The dM stars show mean surface fluxes in a variety of emission lines arising throughout the chromosphere and the lower transition region which are very similar to those of the quiet sun. In the one star in which it could be determined the electron density at…
CO Observations of the Cepheus Flare. II. Gamma Rays from the Interstellar Gas and a Possible New COS B Source
Grenier, I. A.; Lebrun, F.
The correlation between the distribution of the interstellar gas in the Cepheus Flare region (100^deg^ <= l <= 141^deg^, 8^deg^ <= b <= 22^deg^) and that of the diffuse gamma radiation originating in these nearby clouds has been studied in detail. A maximum-likelihood analysis has been applied to compare maps of the atomic and molecula…
EXOSAT observation toward S 147 and A 0535+26.
Ballet, J.; Rothenflug, R.; Sauvageot, J. L.
Observations have been made in the direction of the old SNR S 147 with the X-ray satellite Exosat. No emission was detected with the low-energy experiment, constraining the SNR parameters (energy and ambient density) for a Sedov model or a radiative one. A weak source was detected with the medium-energy experiment which could be associated with th…
Massa's Star, HD 93840: A New Extreme BN Supergiant
Walborn, Nolan R.; Nichols-Bohlin, Joy; Fitzpatrick, Edward L.
New optical digital spectrograms of HD 93840 and several comparison objects are presented and discussed, together with IUE high-resolution data for the same stars. The optical observations confirm HD 93840 (BN1 Ib) as an extreme nitrogen-enhanced supergiant, as originally suggested by Massa (1989). The contrasts with HD 96248 (BC1.5 Iab) are espec…
Similarities in the wind characteristics of hot stars.
Prinja, R. K.
The direct observational similarities in the characteristics of winds in a wide selection of hot stars are considered. Data are presented which demonstrate that discrete absorption components are observed in the UV resonance line profiles of WR stars, WR + O type binaries, B supergiants, B emission-line stars, subdwarf O stars, and the central sta…
Mesures de vitesses radiales. IV. Accompagnement AU sol du programme d'observation du satellite Hipparcos.
Duflot, M.; Genty, V.; Mannone, C. +1 more
The paper presents 396 radial velocities of stars distributed in 19 fields of 4 x 4 degrees. The study employs the Fehrenbach objective prism method and the same measuring technique used in a previous paper (Fehrenbach et al., 1987).