Membership determination of open cluster with parametric method: cross entropy

International Symposium on Sun, Earth, and Life

物理学;天文学;生物科学

Fitriana, Itsna Khoirul^1 ; Arifiyanto, M. Ikbal^1

Astronomy Program, Institut Teknologi Bandung, Indonesia^1

关键词: Bivariate gaussian;    Convergent point;    Cross entropy;    Cross-entropy method;    Evolution of galaxies;    Likelihood functions;    Parametric method;    Radial velocity;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/771/1/012031/pdf
DOI  :  10.1088/1742-6596/771/1/012031

来源: IOP

【 摘 要 】

Stellar open clusters are useful for studying the structure and evolution of Galaxy. Determination of the open cluster members can be viewed from their kinematics: proper motion and radial velocity. It is because the star cluster members will have a motion in the same direction, towards a convergent point. Parametric method with a double elliptic bivariate Gaussian function which contains 11 parameters is used as a model of the proper motion distribution. The value of these parameters are determined numerically by cross entropy method. This method is a method of data fitting using the likelihood function whose value is maximized to get the proper parameters. This method solves the problem of determining the initial value that is often difficult to determine in other numerical methods. There are four open clusters which we have analysed: NGC 2244, ASCC 100, NGC 5168, and NGC 2169. The resulting of proper motion parameters of this method matches the parameters in the literature.