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The radial distribution of galactic gamma rays. IV. The whole galaxy.
Strong, A. W.; Grenier, I. A.; Hermsen, W. +6 more
The correlation between diffuse galactic γ-rays and gas tracers is studied using the final COS-B database and H I and CO surveys covering the entire galactic plane. A good quantitative fit to the γ-rays is obtained, with a small gradient in the γ-ray emissivity per hydrogen atom. The average ratio of H2 column density to integrated CO t…
The Far-Ultraviolet Spectra of Early-Type Galaxies
Lauer, Tod R.; Faber, S. M.; Burstein, David +2 more
New and revised ultraviolet erergy distributions are presented based on 97 IUE spectra of 31 early-type galaxies and the bulge of M31. Measurements of the line strength index Mg_2_ and the V magnitude flux with the IUE aperture are included. The average flux between 1250 and 1850 A is combined with the V magnitude to form an ultraviolet/optical (1…
Aspects of the major element composition of Halley's dust
Kissel, J.; Jessberger, E. K.; Christoforidis, A.
The chemical composition of the solid grains from comet Halley can be inferred from impact-ionization time-of-flight mass spectrometry. Halley's dust in the vicinity of the VEGA-1 spacecraft is a mixture of a refractory organic component and unequilibrated silicates, but detailed chemical information on individual particles is difficult to extract…
The X-Ray Spectral Properties of Accretion Disks in X-Ray Binaries
Stella, L.; Parmar, A. N.; White, N. E.
Using EXOSAT observations, the spectral properties of the persistent emission from a number of X-ray burst sources, high-luminosity low-mass X-ray binaries (LMXRB), and galactic black hole candidates are compared with various models for X-ray emission from an accretion disk surrounding a compact object in a binary system. These models include the …
Galactic Evolution and Cosmology: Probing the Cosmological Deceleration Parameter
Takahara, Fumio; Yoshii, Yuzuru
The magnitude-redshift relation, the color-redshift relation, the galaxy number count, the redshift distribution of galaxies, and the extragalactic background light are calculated taking into account the effect of galactic evolution for several values of the cosmological deceleration parameter q_0_ and the redshift of galaxy formation z_F_. The sp…
An Analysis of the Shapes of Ultraviolet Extinction Curves. II. The Far-UV Extinction
Fitzpatrick, Edward L.; Massa, Derck
In this paper we examine the properties of interstellar extinction in the far-ultraviolet region (FUV; λ < 1700 A) utilizing IUE extinction curves for a primary data sample of 45 reddened Milky Way OB stars. These results are combined with those derived for the 2175 A bump in a previous study. We find that IUE extinction curves can be represent…
Ion plasma waves in dusty plasmas: Halley's comet
Formisano, V.; Giordano, M.; de Angelis, U.
We investigate ion waves in a plasma in the presence of massive charged dust particles, a common space-plasma component now known to exist also in planetary rings and comets. We derive an equation describing low-frequency electrostatic perturbations on a non-homogeneous background, where the inhomogeneity is due to a distribution of charged grains…
Spectral Synthesis in the Ultraviolet. II. Stellar Populations and Star Formation in Blue Compact Galaxies
O'Connell, Robert W.; Thuan, Trinh X.; Fanelli, Michael N.
Far-UV spectra of seven blue compact galaxies have been obtained with the IUE satellite. These objects span a range in luminosity of -21 <= M_B_ <= -13. We have investigated their stellar content and star formation history by applying the technique of optimizing population synthesis utilizing the library of far-UV stellar spectra developed b…
The 2.5-12 µm spectrum of comet halley from the IKS-VEGA experiment
Bibring, J. -P.; Encrenaz, T.; Crovisier, J. +14 more
The infrared instrument IKS flown on board the VEGA space probes was designed for the detection of emission bands of parent molecules, and for a measurement of the size and temperature of the thermal emitting nuclear region. The instrument had three channels with cooled detectors: an "imaging channel" designed to modulate the signal of the nucleus…
EXOSAT X-ray observations of the eclipsing magnetic cataclysmic variable EX Hya.
Mason, K. O.; Cordova, F. A.; Rosen, S. R.
Mechanisms for generating the 67-min rotational X-ray modulation in EX Hya are exmined. It is concluded that the dominant process is probably absorption in material accreting onto the polar regions of the white dwarf which is symmetrically distributed about the rotation axis due to the angular offset of the dipole field. The X-ray emitting region …