AN UPDATED CATALOG OF M31 GLOBULAR-LIKE CLUSTERS: UBVRI PHOTOMETRY, AGES, AND MASSES
AN UPDATED CATALOG OF M31 GLOBULAR-LIKE CLUSTERS: UBVRI PHOTOMETRY, AGES, AND MASSES
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DOI：
10.1088/0004-637x/725/1/200
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发表时间：
2010-09
期刊：
影响因子：
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通讯作者：
Z. Fan;R. de Grijs;Xu Zhou
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文献类型：
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作者：
Z. Fan;R. de Grijs;Xu Zhou
我们提出了一个更新的UBVRI光度表，其中包含M31领域的970个天体，选自修订的博洛尼亚目录（RBC v.4.0），分别包括965、967、965、953和827个UBVRI波段的天体，其中205、123、14、126和109个天体以前没有发表过光度表。光度测量使用了本地星系群巡天的档案图像，覆盖了M31长轴的2.2度。详细的比较表明，我们的光度测量与以前所有滤光片的测量结果完全一致。我们重点研究了445个已确认的球状星团和候选星团，包括典型的球状星团和年轻的大质量星团。这些天体的年龄和质量是通过比较观测到的光谱能量分布和简单的恒星群合成得出的。大约一半的星团年龄小于2gyr，这表明M31最近有大量活跃的恒星形成，这与之前的结果一致。我们注意到，光晕中的星团（投影为bbbb30 kpc）由两个不同的组成部分组成：年龄为b>0 Gyr的较老星团和年龄约为1 Gyr的较年轻星团。空间分布表明，年轻星团（<2 Gyr）在空间上与星系盘重合，包括“10 kpc环”、“外环”和M31的晕，而老星团（>2 Gyr）在空间上与凸起和晕相关。我们还估计了M31中445个已确认的星团和候选星团的质量，发现我们的估计与先前公布的值非常吻合。我们发现，没有一个年轻的盘状星团能够在不可避免的与星系盘中巨大的分子云相遇中幸存下来，它们最终将在几个Gyr的时间尺度上被破坏。具体来说，质量为104 M☉的年轻星团预计会在3.0 Gyr内溶解，因此不会演化成球状星团。
We present an updated UBVRI photometric catalog containing 970 objects in the field of M31, selected from the Revised Bologna Catalog (RBC v.4.0), including 965, 967, 965, 953, and 827 sources in the individual UBVRI bands, respectively, of which 205, 123, 14, 126, and 109 objects do not have previously published photometry. Photometry is performed using archival images from the Local Group Galaxies Survey, which covers 2.2 deg2 along the major axis of M31. Detailed comparisons show that our photometry is fully consistent with previous measurements in all filters. We focus on 445 confirmed “globular-like” clusters and candidates, comprising typical globular and young massive clusters. The ages and masses of these objects are derived by comparing their observed spectral-energy distributions with simple stellar population synthesis. Approximately half of the clusters are younger than 2 Gyr, suggesting that there has been significant recent active star formation in M31, which is consistent with previous results. We note that clusters in the halo (rprojected > 30 kpc) are composed of two different components: older clusters with ages >10 Gyr and younger clusters with ages around 1 Gyr. The spatial distributions show that the young clusters (<2 Gyr) are spatially coincident with the galaxy's disk, including the “10 kpc ring,” the “outer ring,” and the halo of M31, while the old clusters (>2 Gyr) are spatially correlated with the bulge and halo. We also estimate the masses of the 445 confirmed clusters and candidates in M31 and find that our estimates agree well with previously published values. We find that none of the young disk clusters can survive the inevitable encounters with giant molecular clouds in the galaxy's disk and that they will eventually be disrupted on timescales of a few Gyr. Specifically, young disk clusters with a mass of 104 M☉ are expected to dissolve within 3.0 Gyr and will, thus, not evolve to become globular clusters.