Izazinzulu ziphucule iindlela zokuthandana zemathiriyeli ye-interstellar kwaye zachonga iinkozo ezindala ezaziwayo zesilicon carbide emhlabeni. Ezi stardusts pre-solar ngobudala, zenziwe ngaphambi kokuzalwa ilanga 4.6 billion kwiminyaka eyadlulayo.
Imeteorite, iMurchison CM2 yawela emhlabeni kwiminyaka engama-50 eyadlulayo ngowe-1969 eMurchison, eOstreliya.
Izazinzulu ziye zachonga imikroskopu Isilicon khabhayithi iinkozo kule meteorite emva phaya ngo-1987. Ezi nkozo zeSilicon carbide (SiC) (ezaziwa ngokuba yi-carborundum) kule meteorite zichongwe njengemvelaphi ye-interstellar kodwa iminyaka yazo khange ifumaneke ngenxa yonyino lwethekhnoloji. Ukusebenzisa iindlela zeenkwenkwezi ngokuthe ngqo ukutshata kwakungenakwenzeka okanye iindlela zokuthandana ezisemgangathweni ezisekelwe ekuboleni kwezinto ezihlala ixesha elide ezinokuthi zisetyenziswe.
Nangona kunjalo, ngenkqubela phambili yokuskena i-electron microscopy kunye 'noble gas mass spectrometry', yenzekile ngoku ukuza kuthi ga ngoku iminyaka yeenkozo zesilicon carbide ezisekwe kwi-neon (Ne) isotopes eveliswe kukuvezwa kweemeteorites kwimitha ye-galactic cosmic kwiinkozo. Imitha ye-cosmic inokungena kwiimeteorites ukufikelela kwiinkozo ze-SiC ukushiya amanqaku ayo malunga nokwakhiwa kwezinto ezintsha ezifana neon. Okukhona utyhileko olude kwimitha ye-galactic ye-cosmic, kokukhona inyuka ukuxinana kwezinto ezintsha kwiinkozo ze-SiC zeemeteorites.
Kolu phononongo, olupapashwe nge-13 kaJanuwari, ngo-2020, izazinzulu, zisebenzisa le ndlela ingasentla, zamisela imitha ye-cosmic ukuvezwa kweminyaka engama-40 yeenkozo ze-silicon carbide ezikhutshwe kwi-meteorite ye-Murchison.
Ngokusekwe kwi-cosmogenic Neon-21 isotopes kwiinkozo, bafumanise ukuba iinkozo zandulela ukuzalwa ilanga. Zimbalwa iinkozo ebezikuluhlu lweminyaka eyi-7 yeebhiliyoni zeminyaka.
Uluhlu lobudala lwalususela ku-3.9 ± 1.6 Ma (okuthetha ukuthi “iMega annum”, isifinyezo seminyaka esisigidi esinye) ukuya ku-∼3 ± 2 Ga (okuthetha ukuthi “iGiga annum”, isifinyezo seminyaka eyibhiliyoni) ngaphambi kokuqala kweSolar System. malunga 4.6 Ga eyadlulayo.
Oku kuthetha ukuba iinkozo ze-SiC kwi-meteorite ye-Murchison CM2 yeyona nto indala kakhulu emhlabeni ilanga.
Izazinzulu ziye zagqiba kwelokuba ngoku, "i-Neon-21 exposure age dating" yindlela esebenzayo kuphela yokuqinisekisa iminyaka yeenkozo zangaphambi kwelanga kwimeteorite.
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{Unokufunda iphepha lokuqala lophando ngokunqakraza ikhonkco le-DOI elinikwe ngezantsi kuluhlu lwemithombo ecatshulweyo (s)}
Umthombo (s)
1. Heck PR et al., 2020: Ixesha lobomi bothuli lwe-interstellar oluvela kwi-cosmic ray exposure yobudala be-presolar silicon carbide. I-PNAS yapapashwa okokuqala nge-13 kaJanuwari 2020. DOI: https://doi.org/10.1073/pnas.1904573117
2. U-Eugster et al.,—–: IiRekhodi ze-Irradiation, i-Cosmic-Ray Exposure Ages, kunye namaxesha okuDluliswa kweeMeteorites. Iyafumaneka kwi-intanethi https://www.lpi.usra.edu/books/MESSII/9004.pdf. Kufumaneka kwi-14 uJanuwari 2020.
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