CHEMICALLY ANOMALOUS, PREACCRETIONALLY IRRADIATED GRAINS IN INTERPLANETARY DUST FROM COMETS

被引:383
作者
BRADLEY, JP
机构
[1] MVA, Incorporated, Norcross, GA 30093, 5500 Oakbrook Parkway
关键词
D O I
10.1126/science.265.5174.925
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
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.
引用
收藏
页码:925 / 929
页数:5
相关论文
共 73 条