The absorption of soft X-rays from the Crab nebula

Results of an experimental measurement of the soft X-ray spectrum of the Crab nebula in the energy range of 0.5 to 10 keV made with gas proportional counters on board a Centaur IIA rocket launched from the Thumba Equatorial Rocket Launching Station in India are presented. The instrumentation, flight...

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Bibliographic Details
Published in:Astrophysics and space science 1975-02, Vol.32 (2), p.431-446
Main Authors: Iyengar, V. S., Naranan, S., Sreekantan, B. V.
Format: Article
Language:English
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Summary:Results of an experimental measurement of the soft X-ray spectrum of the Crab nebula in the energy range of 0.5 to 10 keV made with gas proportional counters on board a Centaur IIA rocket launched from the Thumba Equatorial Rocket Launching Station in India are presented. The instrumentation, flight details, and data analysis procedure are described, and previously obtained values for the hydrogen column density, interstellar absorption coefficients, and abundance of elements are discussed. The experimental results clearly show absorption of X-rays below 2 keV, and the hydrogen column density is calculated as 3.5 times 10 to the 21st H atoms /sq cm, a factor of 2 higher than the density obtained from 21 cm radio observations, but well within the range deducible from satellite UV measurements and the measured visible extinction coefficients for the Crab nebula. The absorption of X-rays in the interstellar dust is discussed.
ISSN:0004-640X
1572-946X
DOI:10.1007/BF00643155