*Hidenori Terasaki1, Yuta Shimoyama1, Mayumi Maki1, Fuyuka Kurokawa1, Satoru Urakawa2, Keisuke Nishida3, Ryunosuke Saito1, Yusaku Takubo1, Yuki Shibazaki4, Tatsuya Sakamaki4, Akihiko Machida5, Yuji Higo6, Tadashi Kondo1
(1.Graduate School of Science, Osaka University, 2.Graduate School of Natural Science and technology, Okayama University, 3.Graduate School of Science, The University of Tokyo, 4.Graduate School of Science, Tohoku University, 5.Natural Institutes for Quantum and Radiological Science and Technology, 6.Japan Synchrotron Radiation Research Institute)
Keywords:Mars, Core, liquid, sound velocity, density
To give a constraint core composition and interior structures of terrestrial planets, elastic properties, such as sound velocity and density, of liquid Fe-light element alloys at high pressure are required together with geodesy observations. In this study, we have measured sound velocity and density of liquid Fe-Ni-S (S=17-30 at%) using ultrasonic pulse-echo and X-ray absorption methods combined with multianvil apparatus up to 14 GPa and studied the effects of pressure and sulfur content on the elastic properties.
Measured sound velocity (VP) of liquid Fe-Ni-S increased non-linearly with pressure and its pressure dependence is well fitted by the Birch-Murnaghan equation of state. Obtained bulk modulus of liquid Fe-Ni-S decreases with increasing sulfur content. Based on these obtained properties, we will discuss estimated radius and sulfur content of Martian core by comparison with observed moment of inertia data of Mars.