报告题目：Exact solution for fast rotating polytrope and its application to the fast spinner β Pictoris b

　　报 告 人：孔大力 博士（上海天文台, University of Exeter）

　　摘    要：Many gaseous planets and stars are rapidly rotating and can be approximately described by a polytropic equation of state with index unity. We present the first exact analytic solution, under the assumption of the oblate spheroidal shape, for an arbitrarily rotating gaseous polytrope with index unity in hydrostatic equilibrium, giving rise to its internal structure and gravitational field. The new exact solution is derived by constructing the non-spherical Green’s function in terms of the oblate spheroidal wave function. We then apply the exact solution to a young extrasolar gas giant planet, β Pictoris b. Based on the newly measured parameters – the rotation period of the planet, its mass and radius, we are able to compute its non-spherical shape, internal density/pressure distribution and gravitational zonal coefficients.

　　时    间：2015年6月19日 星期五 上午10:00

　　地    点：（北京西路2号）紫台大楼619会议室

　　联 系 人：董瑶（83332059）

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                                                  紫金山天文台学术委员会