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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…
The carbon and nitrogen abundances in WN and WC Wolf-rayet stars.
Willis, A. J.; Smith, L. J.
New ultraviolet spectroscopy obtained with the IUE satellite of helium, carbon and nitrogen lines in six WN and four WC stars have been analysed using non-LTE Escape Probability techniques to derive the stellar atmospheric C/N, C/He and N/He ratios. The derived C/N ratio is found to lie in the range: 0.02-0.06 for WNE stars; 0.006-0.04 for WNL sta…
Discovery of highly ionized species in the ultraviolet spectrum of Feige 24.
Raymond, J. C.; Dupree, A. K.
A high-resolution ultraviolet spectrum of the nearby (90 pc) white dwarf binary Feige 24 (DA + M1-2 V) obtained with the International Ultraviolet Explorer satellite (IUE) reveals two sets of absorption features in the species C IV, Si IV, and N V. The low-velocity component (V approximately 1 km/s) arises from the local interstellar gas apparentl…
OH fluorescence in comets - Fluorescence efficiency of the ultraviolet bands
A'Hearn, M. F.; Schleicher, D. G.
The present investigation is concerned with the calculation of the fluorescence efficiency of OH over a wide range of heliocentric radial velocities. Three vibrational states in each of the two lowest electronic states are included in these calculations, producing a total of nine vibrational bands in the ultraviolet. The attempt is made to reprodu…