Ua hoʻomaikaʻi ka poʻe ʻepekema i nā ʻenehana kaʻina hana o nā mea interstellar a ʻike i nā huaʻai kahiko loa o ka silicon carbide ma ka honua. ʻO kēia mau lepo hōkū ma mua o ka lā, i hana ʻia ma mua o ka hānau ʻana o lā 4.6 biliona makahiki aku nei.
Ua hāʻule ka meteorite, ʻo Murchison CM2 i ka honua i 50 mau makahiki i hala ma 1969 ma Murchison, Australia.
Ua ʻike ka poʻe ʻepekema i ka microscopic kālika silikone ʻO kēia mau huaʻai Silicon carbide (SiC) (ʻike nui ʻia ʻo carborundum) i loko o kēia meteorite ua ʻike ʻia he interstellar i ke kumu akā ʻaʻole hiki ke ʻike ʻia ko lākou mau makahiki ma muli o nā palena ʻenehana. Ke noi ʻana i nā ʻano astronomical no ka pololei ka launa pū ʻAʻole hiki ke hoʻohana ʻia nā ʻano hana maʻamau e pili ana i ka palaho o ka mea radioactive lōʻihi.
Eia nō naʻe, me ka holomua o ka scanning electron microscopy a me 'noble gas mass spectrometry', ua hiki i kēia manawa i nā makahiki o nā ʻōpala silika carbide e pili ana i nā isotopes neon (Ne) i hana ʻia e ka ʻike ʻana o nā meteorites i nā kukuna cosmic galactic i loko o ka palaoa. Hiki i nā kukuna cosmic ke komo i nā meteorites a hiki i nā kīʻaha SiC e waiho i kāna mau hōʻailona ma ke ʻano o ka hoʻokumu ʻana i nā mea hou e like me ka neon. ʻOi aku ka lōʻihi o ka ʻike ʻana i nā kukuna galactic cosmic, ʻoi aku ka kiʻekiʻe o ka neʻe ʻana o nā mea hou i loko o nā kīʻaha SiC o nā meteorites.
I loko o kēia noiʻi, i paʻi ʻia ma Ianuali 13, 2020, ua hoʻoholo nā ʻepekema, me ka hoʻohana ʻana i ke ʻano o luna, i hoʻoholo i ka hōʻike ʻana o nā kukui cosmic i nā makahiki o 40 mau hua silicon carbide i lawe ʻia mai ka meteorite Murchison.
Ma muli o ka cosmogenic Neon-21 isotopes i loko o nā kīʻaha, ua ʻike lākou i ka mua o ka hānau ʻana o nā hua. lā. ʻO ka liʻiliʻi o nā hua i loko o ka makahiki o 7 biliona makahiki.
ʻO ka pae makahiki mai 3.9 ± 1.6 Ma (ʻo ia hoʻi "Mega annum", pōkole no hoʻokahi miliona mau makahiki) a hiki i ~ 3 ± 2 Ga (ʻo ia hoʻi "Giga annum", pōkole no hoʻokahi piliona makahiki) ma mua o ka hoʻomaka ʻana o ka Pūnaehana Lā. ma kahi o 4.6 Ga aku nei.
ʻO kēia ka manaʻo o nā kīʻaha SiC i ka Murchison meteorite CM2 ka mea kino kahiko loa ma ka honua ma mua o ka hānau ʻana o lā.
Ua hoʻoholo hou ka poʻe ʻepekema i kēia manawa, ʻo "Neon-21 exposure age dating" ʻo ia wale nō ka hana kūpono e ʻike ai i ka makahiki o nā hua mua o ka lā i ka meteorite.
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Puna (s)
1. Heck PR et al., 2020: ʻO ke ola o ka lepo interstellar mai ka ʻike ʻana o nā kukui cosmic i nā makahiki o ka presolar silicon carbide. Ua paʻi mua ʻia ʻo PNAS ma Ianuali 13, 2020. DOI: https://doi.org/10.1073/pnas.1904573117
2. Eugster et al.,—–: Nā moʻolelo iradiation, Cosmic-Ray Exposure Ages, and Transfer Time of Meteorites. Loaʻa ma ka pūnaewele ma https://www.lpi.usra.edu/books/MESSII/9004.pdf. Loaʻa ʻia ma 14 Ianuali 2020.
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