恆星誕生於星團的環境當中。目前觀測到星團當中，恆星數量隨質量減少，也就是小質量的恆星遠遠多於大質量的恆星，這個初始質量函數一般與星球系統的環境無關，因此應該與恆星形成機制有關，但是造成一致性初始質量函數的機制尚不清楚。在空間分布上，大質量恆星常常位於星團的中央，而小質量恆星則散佈在比較大的區域，這個質量分層的效應部分受分子雲初始物理條件所影響，另方面則是恆星彼此重力交互作用的結果。我們將延續過去幾年台灣與印度雙方學者之合作，進行星團的觀測研究，具體課題包括（1）利用2MASS 與Pan-STARRS 等巡天資料尋找未知的銀河系星團，並針對已經星團指認低質量成員星，這個星團樣本會比目前所知完整得多，不僅提供研究星團動力演化的重要數據，也提供探討銀河盤形成與演化的關鍵工具；（2）觀測年輕星團以推導不同環境下之初始質量函數並研究質量分層效應，以研究恆星形成與早期演化的過程，以及大質量恆星對於分子雲與促進小質量恆星形成所扮演的角色。 Most, and likely all, stars form out of collapsing molecular clouds in clustered environments. It has been known that low-mass stars outnumber massive stars, described as the initial mass function (IMF), in stellar systems from small star groups to clusters, to galaxies. The origin of a seemingly universal IMF is still largely unknown. Generally, massive stars are seen to concentrate near the center of a young star cluster, whereas lower-mass stars disperse in a larger volume. This effect of mass segregation is thought due partly to the original structure in the parental cloud and partly to the subsequent gravitational dynamics between member stars. We propose to strengthen the ongoing collaboration between the Taiwanese and Indian groups to conduct a systematic investigation of star clusters. Specifically, we will (1) conduct a search for uncharted star clusters by digital sky survey data such as 2MASS and Pan-STARRS. Low-mass members in known clusters will be identified. The comprehensive sample of Galactic open clusters will be a valuable tool not only for cluster evolution (mass segregation, stellar evaporation), but also for probing the formation and evolution of Galactic disk, (2) study a sample of open clusters in different Galactic environments to derive their IMFs, effect of mass segregation, and in particular, how massive stars influence the molecular clouds and induce the formation of nextgeneration stars. 研究期間：9901 ~ 9912
