A New Astrophysical Setting for Chondrule Formation
Alexander N. Krot,1*
Anders Meibom,2
Sara S. Russell,3
Conel M. O'D. Alexander,4
Timothy E. Jeffries,3
Klaus Keil1
Chondrules in the metal-rich meteorites Hammadah al
Hamra 237 and QUE 94411 have recorded highly energetic thermal events that resulted in complete vaporization of a dusty region of the solar
nebula (dust/gas ratio of about 10 to 50 times solar). These chondrules
formed under oxidizing conditions before condensation of iron-nickel
metal, at temperatures greater than or equal to 1500 K, and were
isolated from the cooling gas before condensation of moderately
volatile elements such as manganese, sodium, potassium, and sulfur.
This astrophysical environment is fundamentally different from
conventional models for chondrule formation by localized, brief,
repetitive heating events that resulted in incomplete melting of solid
precursors initially residing at ambient temperatures below
approximately 650 K.
1 Hawai'i Institute of Geophysics and
Planetology (HIGP), School of Ocean and Earth Science and Technology
(SOEST), University of Hawai'i at Manoa, Honolulu, HI 96822, USA.
2 Geological and Environmental Sciences, 320 Lomita Mall, Stanford University, Stanford, CA 94305-2115, USA.
3 Department of Mineralogy, The Natural History
Museum, Cromwell Road, London, SW7 5BD, UK.
4 Department of Terrestrial Magnetism, Carnegie
Institution of Washington, 5241 Broad Branch Road NW, Washington, DC
20015, USA.
*
To whom correspondence should be addressed. E-mail:
sasha{at}pgd.hawaii.edu
