Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.

Science 12 August 1994:
Vol. 265. no. 5174, pp. 925 - 929
DOI: 10.1126/science.265.5174.925
Prev | Table of Contents | Next

Articles

Chemically Anomalous, Preaccretionally Irradiated Grains in Interplanetary Dust from Comets

John P. Bradley 1

1 MVA, Incorporated, 5500 Oakbrook Parkway, #200, Norcross, GA 30093, USA.

Nonstoichiometric grains with depletions of magnesium and silicon (relative to oxygen) and inclusions of iron-nickel metal and iron-rich sulfides have been identified in interplanetary dust particles from comets. These chemical anomalies accumulate in grains exposed to ionizing radiation. The grains, known as GEMS (glass with embedded metal and sulfides), were irradiated before the accretion of comets, and their inferred exposure ages, submicrometer sizes, and "amorphous" silicate structures are consistent with those of interstellar silicate grains. The measured compositional trends suggest that chemical (as well as isotopic) anomalies can be used to identify presolar interstellar components in primitive meteoritic materials.

Submitted on January 24, 1994
Accepted on June 24, 1994


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Comparison of Comet 81P/Wild 2 Dust with Interplanetary Dust from Comets.
H. A. Ishii, J. P. Bradley, Z. R. Dai, M. Chi, A. T. Kearsley, M. J. Burchell, N. D. Browning, and F. Molster (2008)
Science 319, 447-450
   Abstract »    Full Text »    PDF »
Oxygen in the Interstellar Medium.
A. G. Jensen, F. Markwick-Kemper, and T. P. Snow (2008)
Reviews in Mineralogy and Geochemistry 68, 55-72
   Abstract »    Full Text »    PDF »
Oxygen in Comets and Interplanetary Dust Particles.
S. A. Sandford, S. Messenger, M. DiSanti, L. Keller, and K. Altwegg (2008)
Reviews in Mineralogy and Geochemistry 68, 247-272
   Abstract »    Full Text »    PDF »
Mineralogy and Petrology of Comet 81P/Wild 2 Nucleus Samples.
M. E. Zolensky, T. J. Zega, H. Yano, S. Wirick, A. J. Westphal, M. K. Weisberg, I. Weber, J. L. Warren, M. A. Velbel, A. Tsuchiyama, et al. (2006)
Science 314, 1735-1739
   Abstract »    Full Text »    PDF »
Deep metastable eutectic condensation in Al-Fe-SiO-H2-O2 vapors: Implications for natural Fe-aluminosilicates.
F. J.M. Rietmeijer, J. A. Nuth, P. Rochette, J. Marfaing, A. Pun, and J. M. Karner (2006)
American Mineralogist 91, 1688-1698
   Abstract »    Full Text »    PDF »
An Astronomical 2175 A Feature in Interplanetary Dust Particles.
J. Bradley, Z. R. Dai, R. Erni, N. Browning, G. Graham, P. Weber, J. Smith, I. Hutcheon, H. Ishii, S. Bajt, et al. (2005)
Science 307, 244-247
   Abstract »    Full Text »    PDF »
Discovery of Ancient Silicate Stardust in a Meteorite.
A. N. Nguyen and E. Zinner (2004)
Science 303, 1496-1499
   Abstract »    Full Text »    PDF »
Carbon and Nitrogen Isotopic Anomalies in an Anhydrous Interplanetary Dust Particle.
C. Floss, F. J. Stadermann, J. Bradley, Z. R. Dai, S. Bajt, and G. Graham (2004)
Science 303, 1355-1358
   Abstract »    Full Text »    PDF »
Special Feature: Constraints on nebular dynamics and chemistry based on observations of annealed magnesium silicate grains in comets and in disks surrounding Herbig Ae/Be stars.
H. G. M. Hill, C. A. Grady, J. A. Nuth III, S. L. Hallenbeck, and M. L. Sitko (2001)
PNAS 98, 2182-2187
   Abstract »    Full Text »    PDF »
Stable Isotope Variations in Extraterrestrial Materials.
K. D. McKeegan, K. D. McKeegan, and L. A. Leshin (2001)
Reviews in Mineralogy and Geochemistry 43, 279-318
   Full Text »    PDF »


To Advertise     Find Products

Science. ISSN 0036-8075 (print), 1095-9203 (online)