Search Publications
The ultra-violet spectrum of the peculiar early-type supergiant, HD 157038.
Dufton, P. L.; Lennon, D. J.
Ultra-violet spectra of the nitrogen rich supergiant, HD 157038, are presented and compared with those of the normal supergiant, HD 148379. The P-Cygni profiles of the Si IV and C IV resonance lines are very similar, implying that the stars have similar masses; this is evidence against HD 157038 being in a post red supergiant evolutionary stage an…
Detection of Lyman alpha in the spectrum of a white dwarf with heliumatmosphere.
Koester, D.; Weidemann, V.
The detection of Ly-alpha absorption in a low dispersion IUE spectrum of the DBA white dwarf G200-39 is reported. The geocoronal emission was reduced by using a small aperture. For effective temperatures between 12,000 and 16,000, and log n(H)/n(He) values of -5, -4.5, -4, and -3.5, calculations giving colors and line strengths for He I 4472 A, H-…
The reflection nebula around HD 26676.
Centurion, M.; Vladilo, G.
The gaseous component of the reflection nebula surrounding HD 26676 is investigated by comparing the UV spectrum of the star with that of the foreground star HD 26793. The physical properties of the cloud are constrained under the assumption of Mg photoionization and H ionization by cosmic rays and taking into account the effect of the stellar rad…
An upper limit on the high-energy gamma-ray emission of VELA X-1.
Kanbach, G.; Oegelman, H.; Mattox, J. R.
The possibility of high-energy gamma-ray emission from the X-ray binary Vela X-1 was investigated by analyzing the COS-B satellite observations, using the COS-B X-ray detector for a phase coherent analysis in the search of rotational periodicity. The rotational upper limit is compared to the X-ray, TeV, and PeV fluxes reported by Chodil et al. (19…
Perturbations of Test Mass Motion in the Schwarzschild Spacetime Using the Method of Hamilton and Jacobi.
Friedjung, M.; Andrade, A. A.
This thesis develops and applies Hamilton-Jacobi perturbation theory to describe relativistic test mass motion in the Schwarzschild spacetime. The form of Hamiltonian used is rigorously derived from the relativistic Lagrangian. A justification for other choices of Hamiltonians is also given. The results of all the intermediate calculations needed …
HD 145206 : the first semibarium star with a main-sequence close companion ?
Jorissen, A.; Boffin, H. M. J.
A 12 A/mm photographic spectrum of the binary red giant HD 145206 revealed slightly enhanced s-process lines with respect to standard stars of the same temperature and luminosity. The spectrum closely resembles that of a Ba0.5 semibarium star (following the classification of Keenan and Pitts, 1980) used for comparison. The mass transfer scenario g…