Boron in presolar silicon carbide grains from supernovae

被引:22
作者
Hoppe, P
Lodders, K
Strebel, R
Amari, S
Lewis, RS
机构
[1] Max Planck Inst Chem, Abt Kosmochem, D-55020 Mainz, Germany
[2] Washington Univ, Dept Earth & Planetary Sci, Planetary Chem Lab, St Louis, MO 63130 USA
[3] Washington Univ, Space Sci Lab, St Louis, MO 63130 USA
[4] Washington Univ, Dept Phys, St Louis, MO 63130 USA
[5] Univ Chicago, Enrico Fermi Inst, Chicago, IL 60637 USA
关键词
circumstellar matter; dust; extinction; nuclear reactions; nucleosynthesis; abundances; supernovae : general;
D O I
10.1086/320075
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
Eleven presolar silicon carbide grains of type X separated from the Murchison meteorite have been analyzed for boron abundances and isotopic compositions by secondary ion mass spectrometry. Boron concentrations are low with typical B/Si ratios of approximate to1 x 10(-5). The average B-11/B-10 ratio of 3.46 +/- 1.39 is compatible with the solar system value but might be affected by contaminating boron of laboratory origin. These data are compared with theoretical predictions for Type II supernovae, the most likely parent stars of X grains. The B/Si ratios of X grains are much lower (more than an order of magnitude on average) than expected from Type II supernova shell-mixing of matter from the C- and Si-rich zones, contrary to other elemental ratios such as Al/Si and Ti/Si. Condensation calculations show that with C/O > 1 in the ejecta, boron and aluminum will readily condense as BN and AlN, respectively, into silicon carbide, and the B/Al ratio is expected to remain constant. The nitrogen, aluminum, and titanium abundances in SiC X grains are well reproduced by the condensation calculations. Given the similarity of the boron and aluminum condensation chemistry and the generally expected high B/Al ratios (relative to solar) in Type II supernova mixtures with C/O > 1, the observed difference between measured and predicted B/Al ratios must be considered a serious problem. Possible solutions include (1) lower than predicted boron production from Type II supernovae, (2) complex mixing scenarios in supernova ejecta involving only sublayers of the C-rich zones, and (3) formation of silicon carbide under conditions with C/O < 0.1.
引用
收藏
页码:478 / 485
页数:8
相关论文
共 58 条
[1]   INTERSTELLAR SIC WITH UNUSUAL ISOTOPIC COMPOSITIONS - GRAINS FROM A SUPERNOVA [J].
AMARI, S ;
HOPPE, P ;
ZINNER, E ;
LEWIS, RS .
ASTROPHYSICAL JOURNAL, 1992, 394 (02) :L43-L46
[2]   INTERSTELLAR GRAINS IN METEORITES .1. ISOLATION OF SIC, GRAPHITE, AND DIAMOND - SIZE DISTRIBUTIONS OF SIC AND GRAPHITE [J].
AMARI, S ;
LEWIS, RS ;
ANDERS, E .
GEOCHIMICA ET COSMOCHIMICA ACTA, 1994, 58 (01) :459-470
[3]   INTERSTELLAR GRAINS IN PRIMITIVE METEORITES - DIAMOND, SILICON-CARBIDE, AND GRAPHITE [J].
ANDERS, E ;
ZINNER, E .
METEORITICS, 1993, 28 (04) :490-514
[4]   ABUNDANCES OF THE ELEMENTS - METEORITIC AND SOLAR [J].
ANDERS, E ;
GREVESSE, N .
GEOCHIMICA ET COSMOCHIMICA ACTA, 1989, 53 (01) :197-214
[5]   Constraints on stellar grain formation from presolar graphite in the murchison meteorite [J].
Bernatowicz, TJ ;
Cowsik, R ;
Gibbons, PC ;
Lodders, K ;
Fegley, B ;
Amari, S ;
Lewis, RS .
ASTROPHYSICAL JOURNAL, 1996, 472 (02) :760-&
[6]   The revised COMPTEL Orion results [J].
Bloemen, H ;
Morris, D ;
Knödlseder, J ;
Bennett, K ;
Diehl, R ;
Hermsen, W ;
Lichti, G ;
van der Meulen, RD ;
Oberlack, U ;
Ryan, J ;
Schönfelder, V ;
Strong, AW ;
de Vries, C ;
Winkler, C .
ASTROPHYSICAL JOURNAL, 1999, 521 (02) :L137-L140
[7]  
BLOEMEN H, 1994, ASTRON ASTROPHYS, V281, pL5
[8]   PRODUCTION AND EVOLUTION OF LIGHT-ELEMENTS IN ACTIVE STAR-FORMING REGIONS [J].
CASSE, M ;
LEHOUCQ, R ;
VANGIONIFLAM, E .
NATURE, 1995, 373 (6512) :318-319
[9]   Analytical procedures for the measurement of boron isotope compositions by ion microprobe in meteorites and mantle rocks [J].
Chaussidon, M ;
Robert, F ;
Mangin, D ;
Hanon, P ;
Rose, EF .
GEOSTANDARDS NEWSLETTER-THE JOURNAL OF GEOSTANDARDS AND GEOANALYSIS, 1997, 21 (01) :7-17
[10]   NUCLEOSYNTHESIS OF B-11-RICH BORON IN THE PRE-SOLAR CLOUD RECORDED IN METEORITIC CHONDRULES [J].
CHAUSSIDON, M ;
ROBERT, F .
NATURE, 1995, 374 (6520) :337-339