Results 221 to 230 of about 14,587 (250)

Biochemical chromophores and the interstellar extinction at ultraviolet wavelengths

Astrophysics and Space Science, 1979
Interstellar absorption observations at ultraviolet wavelengths are explained on the basis of chromophores in microbiological systems.
Fred Hoyle
exaly   +2 more sources

FUSE Far Ultraviolet Dust Extinction Curves

AIP Conference Proceedings, 2009
Far‐ultraviolet dust extinction curves for 75 sightlines have been created using Far‐Ultraviolet Spectroscopic Explorer (FUSE) observations. This represents the largest sample of far‐UV extinction curves ever measured. The FUSE archive was searched for all observations of stars with existing good IUE or STIS ultraviolet extinction curves.
Geoffrey Clayton
exaly   +2 more sources

Extinction in the far ultraviolet

Physica, 1969
Interstellar grain model consisting of elongated dielectric particles represented by infinite circular cylinders reproducing observed interstellar extinction in IF far UV ...
J.M. Greenberg, G.A. Shah
openaire   +1 more source

Far-ultraviolet extinction in σ Scorpii

Astrophysics and Space Science, 1975
It was found earlier from OAO-2 data (Bless and Savage, 1972) that considerable variability with direction in space is present in both the shape and level (relative to B-V color excess) of the interstellar extinction curve in the far ultraviolet. The star σ Sco was shown to be a case of extremely low UV extinction, but there was some question of ...
Theodore P. Snow, Donald G. York
openaire   +1 more source

Microdiamonds and the Ultraviolet Extinction of Starlight

Astrophysics and Space Science, 1998
Nanometre-sized microdiamonds of the type recently discovered in meteorites could make up a significant fraction of interstellar carbon, and thus explain the observed excess of interstellar extinction at ultraviolet wavelengths.
N.C. Wickramasinghe, F. Hoyle
openaire   +1 more source

Mid Infrared Excess and Ultraviolet Extinction

1987
Correlations between the mid infrared excess and the UV extinction parameters are investigated, using a sample of 50 stars reported to have peculiar extinction properties. No correlation is found between the mid infrared excess and the 2175 A extinction bump, suggesting that the carriers of the UV bump and the mid infrared emission are different.
COX, P, LEENE, A
openaire   +2 more sources

Ultraviolet Extinction as a Key to Grain Optical Properties in the Infrared and Ultraviolet

1986
The paper summarizes the results of a large study of UV extinction based on IUE spectra. The analysis of variations in UV extinction between individual lines of sight is used to separate the contributions of individual grain populations and to constrain their properties.
G. Chlewicki, J. Mayo Greenberg
openaire   +1 more source

Investigation of the Ultraviolet Interstellar Extinction Curve

Publications of the Astronomical Society of the Pacific, 2001
The effect of the interstellar medium (ISM) on ultraviolet radiation is striking; there is a prominent extinction feature (a “bump”) near 2175 A (4.6 mm ). Since its discovery, the carrier of this feature has been linked to graphite dust grains. However, a study of several Galactic lines of sight using International Ultraviolet Explorer (IUE) data (E ...
openaire   +1 more source

Ultraviolet extinction measurements of molecular oxygen density

Journal of Geophysical Research: Space Physics, 1978
Observations of the atmospheric extinction of solar ultraviolet radiation in the 142‐ to 149‐nm and 155‐ to 168‐nm bands have been used to determine molecular oxygen densities over the 100‐ to 160‐km altitude range in a series of rocket flights from Woomera, Australia (31°S, 136.5°E). Comparison of data from morning and evening flights made on the same
J. H. Carver, L. A. Davis, B. H. Horton, M. Ilyas   +3 more
openaire   +1 more source

Ultraviolet Extinction of Circumstellar Dust in HD 45677

1998
The far-UV extinction towards a B[e] star has at least two components: interstellar and circumstellar. The observed absorption in the visible and UV range due to circumstellar dust is a medley effect of absorption and scattered stellar radiation light (4), so that its distribution is flatter as it would correspond to dust particles described by high ...
A. Moujtahid, J. Zorec, A. M. Hubert
openaire   +1 more source