Laboratory evidence for ionized polycyclic aromatic hydrocarbons in the interstellar medium
Article Abstract:
The infrared absorption of four molecules, consisting of neutrals and cations were compared to astronomical observations. Polyclic aromatic hydrocarbons (PAH) have been surmised to cause the presence of aromatic species in small carbon particles. The PAH cations were formed by electron impact of sublimed PAH, argon and calcium chloride-4 in vapour phase. Results showed that the formation of interstellar bonds could not be explained entirely by the presence of neutral PAH species. Instead, the cations must be a dominant component to define the formation of interstellar bonds.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1993
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Discovery of interstellar dust entering the earth's atmosphere
Article Abstract:
Asteroids and comets are known to be gravitationally bound to the Sun because they were formed from the solar system. Interstellar comets are expected every few centuries as much as comets are occasionally ejected from the solar nebula. The detection of interstellar dust in the solar system poses technological challenges. The Ulysses spacecraft has detected dust particles in Jupiter. The radar detection of interstellar particles in the earth's atmosphere is being reported.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1996
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Measurement of the opacity of ionized helium in the intergalactic medium
Article Abstract:
Ionized helium (He II) absorption in the intergalactic medium (IGM) was measured using the Hopkins Ultraviolet Telescope at selected quasar HS1700 + 64. The absorption produced a mean flux deficit at redshift range of 2.2 < z 2.6 resulting to an optical depth of 1.00 plus or minus 0.07. Results indicated that He II absorption was mostly recorded in IGM areas of the lowest density.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1996
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