+ Visit NASA.gov + Contact NASA   + Home Collection > NASA  Author > Pendleton, Yvonne  NASA Center > Ames Research Center  Publication Year > 2001-2010 > 2003  Subject > A-C > Astrophysics  Availability Options > Order From Other Sources  Item/Media Type > Preprint  Note: Start a new navigation search by selecting a link above     Previous Record | Next Record + Back to Results   + Printer Friendly Title: The Organic Component of Interstellar Dust Author(s): Pendleton, Yvonne Abstract: The distribution, chemical structure, and formation of organic matter in the interstellar medium are important to our understanding of the overall evolution of dust. The exchange of dust between the dense and diffuse interstellar medium, and the effects of processing on dust within dense clouds will affect the inventory of material available for incorporation into newly forming star and planetary systems. Observational ground-based studies have confirmed the widespread distribution of the 3.4 pm absorption band attributed to aliphatic hydrocarbons in the diffuse interstellar medium of our own galaxy, and in the dusty spectra of a few nearby galaxies, while space based observations from IS0 probed the signatures of corresponding mid-infrared features. Laboratory experiments which utilize both thermal processes and energetic processing by high energy photons and cosmic rays, produce candidate materials which offer close matches to the observed diffuse interstellar medium and extragalactic hydrocarbon absorption features. Through an analysis of the 4000 to 1000 cm (2.5 to 10 micrometers) region of the spectrum of diffuse interstellar medium (DISM) dust compared with the spectra of thirteen chemical entities produced in the laboratory which serve as analogs to the interstellar material, significant constraints have been placed on the applicability of proposed candidate materials to explain the interstellar features. The results indicate that the organic refractory material in the diffuse interstellar medium is predominantly hydrocarbon in nature, possessing little nitrogen or oxygen, with the carbon distributed between the aromatic and aliphatic forms. Long alkane chains H3C-(CH2),- with n much greater than 4 or 5 are not major constituents of this material. Comparisons to laboratory analogs indicate the DISM organic material resembles plasma processed pure hydrocarbon residues much more so than energetically processed ice residues. This result is consistent with a birthsite for the carrier of the 3.4 micrometers band in the outflow region of evolved carbon stars. Comparisons of dust from our own galaxy with that of distant galaxies suggests that the organic component of interstellar dust is widespread and may be an important universal reservoir of prebiotic organic carbon. NASA Center: Ames Research Center Publication Date: [2003] Document Source: Other Sources No Digital Version Available: Go to Tips On Ordering Available Data: Abstract Only Document ID: 20030067420 Publication Information: Number of Pages = 1 Meeting Information: The Astrophysics of Dust Conference, 25-30 May 2003, Estes Park, CO, United States Keywords: COSMIC DUST; INTERSTELLAR MATTER; CARBON; HYDROCARBONS; PLANETARY EVOLUTION; STELLAR EVOLUTION; Accessibility: Unclassified; No Copyright; Unlimited; Publicly available; Updated/Added to NTRS: 2004-11-03 + Back to Top + Sponsored by the NASA Scientific and Technical    Information Program + 2004 Vision for Space Exploration + Freedom of Information Act + NASA Web Privacy Policy and Important Notices + NASA Disclaimers, Copyright Notice,    and Terms and Conditions of Use NASA Official: Calvin Mackey Page Curator: NASA Center for AeroSpace Information (help@sti.nasa.gov) Last Updated: July 5, 2007