We study a Chandra X-ray Observatory ACIS-S observation of the Galactic globular cluster M12. With a 26 ks exposure time, we detect 6 X-ray sources inside the half-mass radius (2.16 arcminutes) of which two are inside the core radius (0.72 arcminutes) of the cluster. If we assume these sources are all associated the globular cluster M12, the luminosity Lx among these sources between 0.3-7.0 keV varies roughly from 10E+30 to 10E+32 ergs s^−1. For identification, we also analyzed the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) data and identified the optical counterparts to five X-ray sources inside the HST field of view. According to the X-ray and optical features, we found 2-5 candidate active binaries (ABs) or cataclysmic variables (CVs) and 0-3 background galaxies within the HST ACS field of view. Based on the assumption that the number of X-ray sources scales with the encounter rate and the mass of the globular cluster, we expect 2 X-ray source inside M12, and the expectation is consistent with our observational results. From the expectation, the number of X-ray sources in M12 is
dominated by the mass term which is the indication of primordial origin of the X-ray sources in globular clusters. Therefore, the existence of identified X-ray sources (possible CVs or ABs) in M12 suggests the primordial origin of X-ray sources in globular clusters which is in agreement with previous studies.

在本篇論文中，我們研究銀河系內球狀星團M12中的X射線光源的光度及光譜行為，並加以分類，其中我們使用錢卓X射線人造衛星（Chandra X-ray Observatory）中的ACIS-S偵測儀之觀測資料。在累計約兩萬六千秒曝光時間的X射線觀測資料中，我們分別在M12的核半徑（core radius, 大小為0.72角分）及半質量半徑（half-mass radius, 大小為2.16角分）中，偵測到兩個及六個X射線光源。若假設這些X射線光源位於球狀星團M12之中，我們可以計算出它們（能量波段在0.3-7.0 keV）的X射線照度落於每秒10E+30耳格到每秒10E+32耳格之間。為了能夠正確分類這些X射線光源，我們還使用哈伯太空望遠鏡（Hubble Space Telescope, HST）中的ACS偵測儀之觀測資料，以之找出與X射線光源相對應的光學對應體。在半質量半徑中共有五個X射線光源位於哈伯太空望遠鏡的視野內，每個X射線光源分別有一到三個光學對應體。我們根據它們個別的X射線波段及光學波段的光譜與光度特性加以分類。分析結果顯示，在五個具有HST光學對應體的X射線光源中，有二到五個可能的活躍雙星系統或激變雙星系統、以及零到三個背景星系。在假設X射線光源數量會與球狀星團的質量和其中星體相遇機率成正比的前提之下，我們預期M12中會偵測到兩個X射線光源，而這也和我們的觀測結果吻合。由上述的正比關係所預測出的兩個X射線光源主要來自於球狀星團質量項的貢獻，而在此關係中，球狀星團的質量為原生雙星系統生成率的指標。因此，存在於M12中的X射線光源（可能為活躍雙星系統或激變雙星系統）提供了它們可能為原生雙星系統的證據，此結果並與前人研究成果吻合。

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