Search Publications
Search for pulsed γ-ray emission from radio pulsars in the COS-B data.
Caraveo, P. A.; Bignami, G. F.; Strong, A. W. +13 more
Pulsed gamma-ray emission from radio pulsars has been sought in a study of pulsar parameters for 145 radio observations, contemporary with gamma-ray observations, by the COS-B spacecraft. No signal has been detected in the 50 MeV-2 GeV energy range of the study, either globally or from individual pulsars. These results indicate that the average pr…
R 127 : an S DOR type variable intermediate between Of and WN.
Stahl, O.; Wolf, B.; Cassatella, A. +4 more
The results of extensive photometric and high resolution spectroscopic observations of the S Dor variable R 127 are presented and discussed. These observations show the star to be hotter than any of its type previously discovered. Its bolometric magnitude is 10.6, its effective temperature is 16,000 K, and its radius is 150 solar radii. The stella…
The distance, temperature, and luminosity of the hypergiant P Cygni (B1 Ia+).
Lamers, H. J. G. L. M.; Cassatella, A.; de Groot, M.
The basic parameters of P Cyg (B1 Ia+) are determined from a study of the overall energy distribution from 1150 A to 6 cm. The color excess of E(B-V) = 0.63 + or - 0.05 is derived from the strength of the interstellar Lyman-alpha line, from the spectral type, and from a comparison of the UV energy distribution with those of other supergiants. The …
Period-activity relations in close binaries.
Vilhu, O.; Rucinski, S. M.
The chromosphere transition region and coronal emissions of late spectral type main sequence stars with rotational periods short enough to bridge the gap between rapidly rotating single stars and contact binaries are analyzed. It is found that very active sample stars do not follow the scaling laws of Ayres et al. (1981) for line intensities origi…
A study of ultraviolet spectra of zeta Aur/VV CEP systems. II. Mass loss of supergiants in zeta Aur, 32 CYG and 31 Cyg.
Reimers, D.; Hempe, K.; Che, A.
This paper describes a method for the determination of mass loss rates of red giants in spectroscopic eclipsing binaries. A non-spherical, three-dimensional line transfer code has been applied to investigate the wind and mass loss of the K supergiants in ζ Aur, 32 Cyg and 31 Cyg. The authors compare theoretical line profiles with IUE observations …
Spectral fine analysis of the extreme helium star BD +10 2179.
Heber, U.
Line blanketed linear transfer of energy (LTE) model atmospheres were used to analyze UV and visual spectra of the extreme He star BD +10.2179. Model inputs included a temperature within 600 K of 16,000 K, an He component totaling 0.989, and a microturbulent velocity within 1.5 km/sec of 7 km/sec. Hydrogen abundance was calculated to be 0.1% by nu…
R66 (Aeq), an LMC B Supergiant with a Massive, Cool and Dusty Wind
Stahl, O.; Leitherer, C.; Bastian, U. +3 more
The LMC's peculiar emission line star R 66 (Aeq) is studied by means of high dispersion spectroscopy and UBV and JHKLM photometry, from which a model is derived which consists of a massive, luminous B-type supergiant surrounded by a dense, cool expanding envelope and a circumstellar dust shell whose temperature is 1100 K at its inner edge. R 66 be…
IUE observations of the high velocity symbiotic star AG Draconis during active phase.
Altamore, A.; Baratta, G. B.; Friedjung, M. +5 more
New high and low resolution IUE spectra of AG Dra, obtained when the star was still in its active phase, are analyzed and interpreted. The spectra are characterized by strong permitted and weak intercombination emission lines belonging to a wide ionization range, from O I, Mg II, to He II, O V, S V, superimposed on an intense continuum. Several st…
The composite UV emission spectrum of Seyfert 1 galaxies.
Tarenghi, M.; Veron, P.; Veron-Cetty, M. P.
A composite spectrum is built in the wavelength range λλ1200-3000 Å, from IUE spectra of 27 Seyfert 1 nuclei. Comparisons with spectra of quasars show that all emission features seen in quasars, including the Fe II UV multiplets, are also observed in the much less luminous Seyfert 1 nuclei. This is taken as a confirmation that Seyfert 1 nuclei are…
A study of UV spectra of zeta Aur/VV CEP stars. IV. System parametersand mass-loss of delta Sge.
Reimers, D.; Schroeder, K. -P.
The orbital elements of the Delta Sge system were improved using new radial velocity measurements. A distance of 170 pc is determined with the assumption that the companion is a mainsequence star with Te = 10,500 K (ca. B9) as found from IUE fluxes. Combining the mass-function with the locations of the components in the HR-diagram, a mass-ratio of…