我們利用 Beijing-Arizona-Taipei-Connecticut (BATC) 多色巡天計畫的資料研究銀河系球狀星團 M13 (NGC 6250) 的成員星族組成。BATC的觀測由北京 60/90 公分史密特望遠鏡取得，視野大小約一平方度，其13個中頻寬濾鏡的光度資料相當於低色散光譜，涵蓋 420--970 nm 波長範圍，能有效提供恆星的分類訊息。分析 M13 星團外圍恆星的色星等圖(color-magnitude diagram) 以及個別恆星之能譜分佈 (spectral energy distribution)，我們獲得星團的演化訊息，以及判別個別恆星是否為星團成員星。由星數密度隨空間分佈的關 係定出M13的半徑約為18角分。從資料中我們發現大質量 成員星有明顯集中於星團中心 6 角分以內的現象，這可能由於動力質量分層，或是在球狀星團核心極高密度環 境下，造成恆星演化異常的結果。 We used CCD photometry, in 13 intermediate bands covering from 420-970nm, on the galactic globular cluster M13 (NGC 6205) to study its stellar population. The data---effectively low-resolution spectroscopy---were taken by the Beijing 60/90 cm Schmidt telescope, with almost a 1-degree field, as part of the Beijing-Arizona -Taipei-Connecticut (BATC) multicolor sky survey. By analysis of both the color-magnitude diagrams and spectral energy distribution of individual stars in the outer region of the cluster, diagnostic information of membership and of the evolutionary status of the cluster has been derived. The cluster radius, as determined by enhancement of stellar number density, is ~ 18'. Our data suggest a concentration of massive stars within 6' of the cluster, which may be the result of dynamical mass segregation or unusual stellar evolution in exceedingly dense environment at the core of a globular cluster.
