Presentation Information
[PPS12-P01]I-Xe Dating of Brecciated Meteorites Containing Solar Wind-Derived Noble Gases to Constrain the Timing of Clearance of the Solar Protoplanetary Disk
*Shuichiro Kawahara1, Hirochika Sumino2, Yuki Hibiya2, Shogo Tachibana3, Atsushi Takenouchi4 (1.Graduate School of Arts and Sciences, The University of Tokyo, 2.Research Center for Advanced Science and Technology, The University of Tokyo, 3.UTokyo Organization for Planetary and Space Science, The University of Tokyo, 4.Kyoto University)
Keywords:
The I-Xe age,Noble gas,Meteorite
During the formation of the solar system, the protoplanetary disk composed of gas and dust formed around the protosun. The dust and gas within it merged to form planetesimals, which then grew into planets through collisions and the accretion of gas and dust.
However, no gaseous disk exists in the current solar system. This indicates that at some point, solar activity intensified, and the disk's constituent material was blown away and dispersed by solar radiation. The exact timing of this event, called the clearing of the protoplanetary disk, has been a key question in planet formation.
We have been investigating the timescale of protoplanetary disk clearing, using noble gases as tracers of gas dispersion and its timing. When gas was present in the protoplanetary disk, the solar wind was prevented from reaching the surfaces of planetesimals. After disk clearing, however, the solar wind could reach the planetesimal surfaces. Additionally, brecciated meteorites are thought to have formed on the surface of their parent bodies, as the gardening effect by bombardment by other small bodies is considered essential for brecciation. They are expected to have acquired significant amounts of solar-wind-derived noble gases when fine powder with a large surface area, exposed to the sun and irradiated by solar wind, was incorporated during gardening. At the same time, the I-Xe age system is considered to have been reset by the Xe loss due to bombardment, and then closed when the fine powder formed a consolidated breccia. Therefore, we propose that determining the I-Xe age and measuring the solar wind-derived noble gas content of brecciated meteorites could enable the timing of the clearing-out of the protoplanetary disk to be determined.
At the presentation, we will show the latest data newly obtained after we reported the relationship between the solar noble gas contents and I-Xe ages of five brecciated meteorites by Arai et al. (Goldschmidt 2021; JpGU 2021 annual meeting).
However, no gaseous disk exists in the current solar system. This indicates that at some point, solar activity intensified, and the disk's constituent material was blown away and dispersed by solar radiation. The exact timing of this event, called the clearing of the protoplanetary disk, has been a key question in planet formation.
We have been investigating the timescale of protoplanetary disk clearing, using noble gases as tracers of gas dispersion and its timing. When gas was present in the protoplanetary disk, the solar wind was prevented from reaching the surfaces of planetesimals. After disk clearing, however, the solar wind could reach the planetesimal surfaces. Additionally, brecciated meteorites are thought to have formed on the surface of their parent bodies, as the gardening effect by bombardment by other small bodies is considered essential for brecciation. They are expected to have acquired significant amounts of solar-wind-derived noble gases when fine powder with a large surface area, exposed to the sun and irradiated by solar wind, was incorporated during gardening. At the same time, the I-Xe age system is considered to have been reset by the Xe loss due to bombardment, and then closed when the fine powder formed a consolidated breccia. Therefore, we propose that determining the I-Xe age and measuring the solar wind-derived noble gas content of brecciated meteorites could enable the timing of the clearing-out of the protoplanetary disk to be determined.
At the presentation, we will show the latest data newly obtained after we reported the relationship between the solar noble gas contents and I-Xe ages of five brecciated meteorites by Arai et al. (Goldschmidt 2021; JpGU 2021 annual meeting).