[S-IT18] Planetary cores: Structure, formation, and evolution

[SIT18-P02] Fe-Ni-軽元素融体の弾性特性から推定される水星核の組成

*寺崎 英紀¹、Rivoldini Attilio²、下山 裕太¹、西田 圭佑³、浦川 啓⁴、黒川 冬華¹、田窪 勇作¹、柴崎 裕樹⁵、坂巻 竜也⁵、町田 晃彦⁶、肥後 祐司⁷、近藤 忠¹ (1.大阪大学大学院理学研究科、2.Royal observatory of Belgium、3.東京大学大学院理学研究科、4.岡山大学大学院自然科学研究科、5.東北大学大学院理学研究科、6.量子科学技術研究開発機構、7.高輝度光科学研究センター)

キーワード：水星、弾性特性、中心核

Knowledge about density and elastic properties, such as bulk modulus, of liquid Fe-Ni-alloys at high pressure are important to constrain the interior structure and composition of planetary cores. Mercury's core is relatively large compared to other terrestrial planets and is at least in a partially molten state (Margot et al. 2007). Recent X-ray spectroscopy data suggests that S of 1-4 wt% exists on the surface, indicating possible existence of some amounts of S in the core (e.g., Chabot et al. 2014). In this study, we have measured sound velocity and density of liquid Fe-Ni-S using ultrasonic pulse-echo and X-ray absorption methods combined with multianvil apparatus up to 14 GPa. The obtained sound velocity and bulk modulus significantly decreased with increasing S concentration especially at lower pressures. We asses the effect of the newly obtained elastic properties on the compositions of Mercury's core.