Results 181 to 190 of about 63,480 (217)

The 3.4-µm interstellar absorption feature

Nature, 1980
Estimation of the organic component of interstellar grains has provoked considerable interest1,2. Recently Duley and Williams2 concluded from an absence of the 3.4-µm CH absorption band in obscured IR sources that organic compounds in grains account for ⩽10% of carbon in the interstellar medium.
D. T. Wickramasinghe, D. A. Allen
openaire   +3 more sources

Diffuse interstellar absorption bands

Science in China Series G: Physics, Mechanics and Astronomy, 2009
The diffuse interstellar bands (DIBs) are a large number of absorption bands that are superposed on the interstellar extinction curve and are of interstellar origin. Since the discovery of the first two DIBs in the 1920s, the exact nature of DIBs still remains unclear.
FuYuan Xiang, ShunLin Liang, AiGen Li
openaire   +1 more source

Interstellar Absorption of Cosmic X Rays

Physical Review D, 1970
Improved results on the total photo-ionization cross section of atomic helium are given. The total cross section includes contributions from simultaneous ionization and excitation of ${\mathrm{He}}^{+}$ and double ionization; the combined effect of these two processes adds about 10% to the normal photo-ionization process where ${\mathrm{He}}^{+}$ is ...
Robert L. Brown, Robert J. Gould
openaire   +1 more source

Interstellar Extinction and Diffuse Absorption Features

Astrophysics and Space Science, 1975
The equivalent width of the λ 2175 A band, W 2175, well known as the big bump in the interstellar extinction curves, has been found to be closely correlated with the colour excess E B-V as well as with the extinction differences E 8−6 and E 8−6 defined to characterize quantitatively the steep slopes of the extinction curves in the far ultraviolet.
openaire   +1 more source

Interstellar absorption in the galactic plane

Astrophysics, 1994
UDC 524.5 We consider the distribution of interstellar absorption in the galactic plane using the classical Cepheids and main sequence stars of spectral classes B0-B3. In the method developed we use pairs of stars with the same absolute stellar magnitude, but with maximal difference of observed colors (B-V), The observed picture corresponds to the ...
R. A. Vardanyan, V. V. Ambaryan, A. V. Pogosyan   +2 more
openaire   +1 more source

Diffuse interstellar absorption and emission bands

AIP Conference Proceedings, 1994
Unidentified astrophysical spectra are discussed including the diffuse interstellar absorption bands and visible emission bands from the Red Rectangle nebula and the R Coronae Borealis star V854 Cen. Assignments for the Red Rectangle optical emision and complementary diffuse absorption bands are not yet established, but comparison of the spectra allows
R. E. Hibbins, J. R. Miles, P. J. Sarre
openaire   +1 more source

Small Scale Distribution of Interstellar Absorption

Nature, 1968
A SURVEY programme to take H α photographs of galactic emission nebulae has been in progress since October 1966 at the Tokyo Astronomical Observatory using the 50 cm Schmidt telescope at the Dodaira Station1. A combination of Eastman Kodak 103a-E plate and Hoya colour glass R64 5 mm thick are being used.
K. ISHIDA, K. AKABANE
openaire   +1 more source

Distribution of stars and interstellar absorption

Vistas in Astronomy, 1962
Abstract The paper is a continuation of two earlier papers concerning the effect of interstellar absorption on the investigation of stellar distribution. It presents a considerable simplification of the formulae developed earlier, and leads not only to the tabulation of arguments but also, in turn, to the construction of tables which can be compared ...
openaire   +1 more source

Investigation into broad interstellar absorption lines

Astronomical & Astrophysical Transactions, 2003
Diffuse interstellar bands (DIBs) are investigated mainly with high-resolution spectroscopy, which allows very fine structures to be detected. However, the rapidly increasing resolution of echelle spectra becomes a disadvantage when broad absorption structures are involved.
openaire   +1 more source

Interstellar Emission and Absorption Lines

2012
Interstellar emission and absorption lines are discussed, including optical recombination lines, the 21cm hydrogen line, and broad lines such as the interstellar Lyman-alpha line. This chapter ends with a discussion of the curve of growth.
openaire   +1 more source