Search Publications
The scattering phase function of interstellar grains : the case of the reflection nebula NGC 7023.
Bohlin, R. C.; Witt, A. N.; Stecher, T. P. +1 more
IUE observations of the reflection nebula NGC 7023 and the illuminating star, HD 200775, in the spectral range from 1300 to 3100 A are combined with ground-based measurements of the nebular brightness distribution at 3500, 4100, 4700, and 5500 A to determine the scattering properties of the nebular dust grains. Total nebular fluxes are derived fro…
P-Cyg profiles observed in the ultraviolet and visible spectra of Wolf-Rayet stars.
Willis, A. J.
A semi-qualitative analysis of the UV P-Cygni line profiles observed in the IUE spectra of seven WN and three WC Wolf-Rayet stars is presented. The velocity characteristics of these profiles are presented and combined with complementary measurements from visible spectra, allowing an inspection of P-Cygni profiles encompassing a wide range of ionic…
The 12 CO/13 CO abundance ratio toward ZET Oph.
Jenkins, E. B.; Wannier, P. G.; Penzias, A. A.
The CO-12/CO-13 abundance ratio toward Zeta Ophiuchi, and interstellar material physical properties, are determined by means of a system of UV absorption lines gathered by Copernicus and IUE spacecraft observations. The observations imply a low CO isotope ratio, at 55 + or - 11, and a CO-12 column density of 2.4 + or - 0.3 x 10 to the 15th/sq cm. …
Ultraviolet and optical spectrum studies of lambda Andromedae : evidence for atmospheric inhomogeneities.
Dupree, A. K.; Baliunas, S. L.
To pursue the study of solar phenomena in cool stars, chromospheric activity in Lambda Andromedae (HD 222107 has been investigated). This binary, whose primary star is G7-G8 IV-III, shows strong chromospheric emissions and is related to the RS CVn-type systems. The first quantitative measurements of chromospheric and solar-type transition-region e…
Detection of further red giants with "Hybrid" atmospheres ANS a possible correlation with double circumstellar MGII and CAII lines.
Reimers, D.
In addition to the three known hybrid atmosphere stars (Alpha and Beta Aqr, and Alpha TrA), the three red giants (Theta Her, Iota Aur and Delta TrA) which have both transition layer lines (N V, C IV, Si IV, C II) and cool winds have been detected. It is shown that all six known hybrid stars have double circumstellar Ca II and Mg II absorption line…
COS-B gamma-ray measurements, cosmic rays and the local interstellar medium
Caraveo, P. A.; Bignami, G. F.; Strong, A. W. +7 more
A study of the relation between galaxy counts and gamma rays measured by the COS-B satellite clearly shows that there exists a bidimensional correlation between these quantities. Though the 21 cm measurements are more accurate than galaxy counts they show a weaker correlation with gamma rays. A significant fraction of the local gas in molecular fo…
The local interstellar medium as traced by gamma rays
Caraveo, P. A.; Bignami, G. F.; Strong, A. W. +8 more
Gamma-ray flux measurements (70-5000 MeV) made with the COS-B satellite have been used to study the distribution of total gas column density in the latitude range from 11 deg to 19 deg. A close correlation with the distribution found from galaxy counts exists. The dominant structure is associated with Gould's Belt, but several other major features…
Production of CS and S in Comet Bradfield /1979 X/
Feldman, P. D.; Jackson, W. M.; Halpern, J. B. +1 more
High and low resolution ultraviolet spectra of carbon monosulfide (CS) in Comet Bradfield (1979 X) were obtained with the IUE satellite. The high resolution rotational profile of the (0, 0) band at 257.5 nm can be fitted with a theoretical profile derived assuming a Boltzmann temperature of 70 K. Spatial plots of the low resolution data for both S…
Very extended ionized gas in radio galaxies-I. A radio, optical and ultraviolet study of PKS 2158-380.
Boksenberg, A.; Penston, M. V.; Snijders, M. A. J. +7 more
IUE observations of PKS 2158-380 show gas in a high state of ionization extending out to a radius of 15 kpc, with a spectrum which is inconsistent with local photoionization by hot stars, and a UV point source at the nucleus which can be fitted by a power law with a spectral index of -1.4. If the gas is distributed within the galaxy in such a way …
RW Sex, a disk with a hot, high-velocity wind.
Oke, J. B.; Greenstein, J. L.
The continuum spectrum of the flickering blue variable RW Sex was observed from 10,000 to 1150 A. The star is a cataclysmic variable currently stabilized at maximum, and the spectrum is dominated by an accretion disk, with flat spectrum in the ultraviolet, except at more than 5000 A, where a blackbody near 7000 K is seen. A distance of 400 pc is d…