火星核的大小与火星物理参数的关系  

RELATIONSHIP BETWEEN THE SIZE OF MARS'CORE AND THE PHYSICAL PARAMETERS OF MARS

作　　者：张承志[1] 

机构地区：[1]南京大学天文系

出　　处：《南京大学学报（自然科学版）》1994年第3期413-421,共9页Journal of Nanjing University（Natural Science）

基　　金：国家自然科学基金

摘　　要：由于目前尚无法获得火星自转轴岁差的精确值，因此难以如同地球或月球那样导出火星的平均惯量矩系数Ｉ／ＭＲ２值．本文利用已知的火星测地学参数并通过对比地球、月球等的研究结果，建立了一组火星内部结构模型，然后估算出与这些模型相对应的火星主惯量矩中的非流体静力学分量．在与其他类地行星比较研究后，表明火星的Ｉ／ＭＲ２在０．３５０～０．３６０间取值是较合理的；这时，火星核的半径在１５２０～１８５０ｋｍ之间取值．本文推荐两个参数化模型（见表５）作为今后理论研究的参考．最后，建议利用ＣＣＤ探测仪器对火卫一和火卫二进行地面天体测量观测，以便检测出火星自转极的运动，从而直接导出火星的Ｉ／ＭＲ２值．Because the exact value of the Martian axial precession is presently unknown, the mean moment-of-inertia ratio, I / MR2, of Mars cannot be derived as it is for the Earth or the Moon. Comparing Mars with the Earth, the Moon, and other terrestrial planets, and using the well-known geodetic parameters of Mars, we constructed a group of Martian nit6rnal structure models. Moreover, we estimated the nonhydrostatic components of the principal monent-of-inertia for these models. By means of the interplanetary comparison we make the following suggestions:(1) The data in table 2 obviously show that the central density, ρ(0), and central pressure, p(0), for the model MARS 93-09 are too high, whereas the mean mantle density,m, for the model MARS 93-01 is too low. This deviates from the knowledge of the chemical composition in Mars'interior. Therefore, if the value of I/MR2 equals 0.345, this seems inconsistent with some known facts.(2) The results obtained in this paper indicate that the reasonable range of the Martian mean moment-of-inertia ratio, I/ MR2, is 0.350￣0.360, meantime the range of the size of Mars'core is 1520 km￣1850 km.(3) The two parametric models listed in Table 5 of this paper can be used for reference in the future theoretical researches.(4) It is necessary for us to be engaged in ground-based astrometric observations of the Martian satellites with the CCD datector. This will certianly allow detection of the Martian polar motion, and will directly derive the mean moment-of-inertia ratio,I/ MR2, of Mars.(5) It seems that the new periodic space exploration will have to include the programme for detection of the size of Mars' core and its character. This will allow improvement of the internal structure models of Mars and will help us to check the adopted value of I/ MR2 of Mars.

关 键 词：火星核 测地学参数 火星 

分 类 号：P185.3[天文地球—天文学]