کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5488056 | 1523907 | 2016 | 6 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Revisiting the lifetime estimate of large presolar grains in the interstellar medium
ترجمه فارسی عنوان
بازبینی تخمینی طول عمر دانه های پیش زرد بزرگ در میان ستاره ای
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کلمات کلیدی
گرد و خاک، تکامل کهکشان، شهاب سنگها، راه شیری، دانه های پیش کالری،
موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
فیزیک زمین (ژئو فیزیک)
چکیده انگلیسی
Some very large (>0.1μm) presolar grains are sampled in meteorites. We reconsider the lifetime of very large grains (VLGs) in the interstellar medium focusing on interstellar shattering caused by turbulence-induced large velocity dispersions. This path has never been noted as a dominant mechanism of destruction. We show that, if interstellar shattering is the main mechanism of destruction of VLGs, their lifetime is estimated to be â³108yr; in particular, very large SiC grains can survive for ~1 Gyr. The lifetimes obtained for VLGs are comparable to the longest residence time derived for some presolar grains based on the cosmic-ray exposure time. However, most presolar SiC grains show residence times significantly shorter than 1 Gyr, which may indicate that there is a more efficient mechanism than shattering in destroying VLGs, or that VLGs have larger velocity dispersions than 10 km sâ1. We also argue that the enhanced lifetime of SiC relative to graphite can be the reason why we find SiC among μm-sized presolar grains, while the abundance of SiC in the normal interstellar grains is much lower than graphite.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Planetary and Space Science - Volume 133, 15 November 2016, Pages 17-22
Journal: Planetary and Space Science - Volume 133, 15 November 2016, Pages 17-22
نویسندگان
Hiroyuki Hirashita, Takaya Nozawa, Ryosuke S. Asano, Typhoon Lee,