分类: 天文学 >> 天体物理学 提交时间: 2023-07-11
摘要: We propose to use the rotation period to constrain the average density of an object with gravitationally confined surface. The average density is inverse proportional to the square of the rotation period, while independent of the size of the object. The lower limit of the average density can be written as $\rho_0=10.9 {\ \rm g\ cm^{-3}}\left(\frac{{\ \rm hours}}{P}\right)^2$. An asteroid with rotating period shorter than 0.7 h should consist of some unknown matter, or it is a whole rock or a bulk of ice with no rubble piles on the surface.