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The atmosphere of subluminous B stars. II. Analysis of 10 helium poor subdwarfs and the birthrate of sdB stars.
Heber, U.
Ultraviolet and visual spectra of 10 helium-poor hot subluminous subdwarfs are analyzed, and the birthrate of these stars is determined. Effective temperatures range from 25,000 - 75,000 K in the group, which includes three binaries. sdB's occupy a narrow range in gravities and photospheric helium content in contrast to the sdOB ranges of gravitie…
Rotational modulation and flares on RS CVn and BY Dra-type stars. I. Photometry and SPOT models for BY Dra, AU Mic, AR Lac, II Peg and V711 Tau (=HR 1099).
Doyle, J. G.; Linsky, J. L.; Cellino, A. +19 more
Multicolor wide-band photometry of five active stars is presented. The observations were carried out at several places before, during and after the period of IUE observations for the purpose of determining the location, sizes, and evolution of photospheric spots at the time when chromospheric, transition region, and coronal activity data were obta…
Distances to planetary nebulae. I. The reddening-distance method.
Pottasch, S. R.; Pel, J. W.; Gathier, R.
Distances to 12 planetary nebulae are derived from the increase of interstellar reddening with distance along the lines of sight of the nebulae. The reddening-distance relations are determined using Walraven VBLUW photometry of stars in small fields around the planetary nebulae. With a theoretical calibration of the VBLUW colors the effective temp…
IRAS spectra of planetary nebulae. III.
Pottasch, S. R.; Mo, J. E.; Preite-Martinez, A. +2 more
Measurements of the IRAS spectra of planetary nebulae are presented. The spectra cover the wavelength 7.5 to 23 microns. The lines observed are mainly from ions of neon and sulfur. The abundance of these two elements is determined and compared to results found in other astronomical objects. It is also found that the Ne(4+) ion, when present, is fo…
Magnetic structure in cool stars. IX. Ultraviolet emission lines from chromospheres and transition regions.
Oranje, B. J.
A compilation of ultraviolet fluxes from 132 stars in the IUE catalog is analyzed in order to study the power-law relations for chromospheric and transition region lines. Flux-flux plots covering 5 decades for transition-region lines and 3.5 decades for chromospheric lines indicate tight power-law relations in the case of single stars, particularl…
The chemical composition of NGC 2363.
Pena, M.; Torres-Peimbert, S.; Peimbert, M.
Photoelectric spectrophotometry in the 3400 - 7400 Å is presented for the metal-poor extragalactic H II region NGC 2363. Based on these data, on IUE observations and on ionization structure models the authors have obtained the chemical abundances. The C/O ratio is a factor of two smaller than in the solar vicinity and under reasonable assumptions …
The empirical BC versus T EFF scale for non-supergiant O9-G5 stars.
Morossi, C.; Malagnini, M. L.; Rossi, L. +1 more
By the analysis of observed energy distributions extending from the UV to the IR, the effective temperature, the gravity and the bolometric correction for a representative sample of nonsupergiant and not chemically peculiar O9-G5 stars are derived in a self-consistent way. The new, improved relationship between the bolometric correction and the ef…
Spectral similarities in the visible and UV spectrum of Herbig Ae/Be stars.
Catala, C.; Czarny, J.; Felenbok, P. +1 more
High resolution spectroscopic observations of pre-main sequence Herbig Ae/Be stars in the P Cygni subclass are reported. The observations were carried out in order to determine whether the envelopes of the stars belonging to the same spectral subclass are similar. The specific stars observed were: HD 250550; BD 46 deg 3471, and HD 150193. The H-al…
The symbiotic star RR Tel.
Nussbaumer, H.; Hayes, M. A.
The time variability of RR Tel in the stronger ultraviolet emission lines is explored, and a decrease in the UV line fluxes over the 1978-1984 period is noted, while no evidence for correlation with the infrared fluxes is found. There is no evidence for periodic variations in the 1200-3200 A line emission, and the brightness derived from the IUE F…
Spectrophotometry of the eclipsing dwarf nova V2051 Ophiuchi.
Watts, D. J.; Bailey, J.; Hill, P. W. +3 more
A detailed phase-dependent spectroscopic study of the eclipsing dwarf nova V2051 Oph is reported. The spectroscopic observations were carried out in the optical and UV wavelengths using the 3.9-meter Anglo-Australian Telescope (AAT) International Ultraviolet Explorer (IUE) spacecraft. The optical spectrum shows strong Balmer emission, as well as w…