Organic globules in the Tagish Lake meteorite: remnants of the protosolar disk.
Coordinated transmission electron microscopy and isotopic measurements of organic globules in the Tagish Lake meteorite shows that they have elevated ratios of nitrogen-15 to nitrogen-14 (1.2 to 2 times terrestrial) and of deuterium to hydrogen (2.5 to 9 times terrestrial). These isotopic anomalies are indicative of mass fractionation during chemical reactions at extremely low temperatures (10 to 20 kelvin), characteristic of cold molecular clouds and the outer protosolar disk. The globules probably originated as organic ice coatings on preexisting grains that were photochemically processed into refractory organic matter. The globules resemble cometary carbon, hydrogen, oxygen, and nitrogen (CHON) particles, suggesting that such grains were important constituents of the solar system starting materials.
Nakamura-Messenger
Keiko
K
Robert M. Walker Laboratory for Space Science, Astromaterials Research and Exploration Science Directorate, NASA Johnson Space Center, Houston, TX 77058, USA. keiko.nakamura-1@nasa.gov
Messenger
Scott
S
Keller
Lindsay P
LP
Clemett
Simon J
SJ
Zolensky
Michael E
ME
D002244:Carbon / Q000032:analysis*; D002247:Carbon Isotopes / Q000032:analysis; D003903:Deuterium / Q000032:analysis; D006859:Hydrogen / Q000032:analysis*; D007053:Ice; D019110:Meteoroids; D009584:Nitrogen / Q000032:analysis*; D009587:Nitrogen Isotopes / Q000032:analysis; D010100:Oxygen / Q000032:analysis; D013696:Temperature; D014466:Ultraviolet Rays
D002247:Carbon Isotopes; D007053:Ice; D009587:Nitrogen Isotopes; D002244:Carbon; D006859:Hydrogen; D003903:Deuterium; D009584:Nitrogen; D010100:Oxygen