H ii REGION LUMINOSITY FUNCTION OF THE INTERACTING GALAXY M51
H ii REGION LUMINOSITY FUNCTION OF THE INTERACTING GALAXY M51
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DOI：
10.1088/0004-637x/735/2/75
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发表时间：
2011-04
期刊：
影响因子：
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通讯作者：
Jong Hwan Lee;N. Hwang;M. Lee
中科院分区：
文献类型：
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作者：
Jong Hwan Lee;N. Hwang;M. Lee
我们提出了一个研究的H II区域在M51使用哈勃太空望远镜先进的相机进行调查的图像作为哈勃遗产计划的一部分。我们已经在M51中编目了大约19，600个H ii区域，其Hα光度范围为L = 1035.5-1039.0 erg s−1。M51中H ii区域（H ii LF）的Hα光度函数可以用双幂律来表示，其指数α = −2.25 ± 0.02（明亮部分）和α = −1.42 ± 0.01（暗部分），在一个断点L = 1037.1 erg s−1处分开。这种断裂在以前对M51 H ii区域的研究中没有发现。与模拟的H ii LF的比较表明，这种断裂是由H ii区电离源的过渡引起的，从低质量的星系团（103 M级，包括几颗OB星）到更大质量的星系团（包括几十颗OB星）。L < 1037.1 erg s− 1的H ii LF在M51的不同部分有不同的斜率：臂间区域的H ii LF比臂和核区域的H ii LF更陡。这种观察到的H ii LFs的差异可以用进化效应来解释：臂间区域的H ii区域比M51其他部分的H ii区域相对更古老。
We present a study of H ii regions in M51 using the Hubble Space Telescope Advanced Camera for Surveys images taken as part of the Hubble Heritage Program. We have cataloged about 19,600 H ii regions in M51 with Hα luminosity in the range of L = 1035.5–1039.0 erg s−1. The Hα luminosity function of H ii regions (H ii LF) in M51 is well represented by a double power law with its index α = −2.25 ± 0.02 for the bright part and α = −1.42 ± 0.01 for the faint part, separated at a break point L = 1037.1 erg s−1. This break was not found in previous studies of M51 H ii regions. Comparison with simulated H ii LFs suggests that this break is caused by the transition of H ii region ionizing sources, from low-mass clusters (with ∼103 M☉, including several OB stars) to more massive clusters (including several tens of OB stars). The H ii LFs with L < 1037.1 erg s−1are found to have different slopes for different parts in M51: the H ii LF for the interarm region is steeper than those for the arm and the nuclear regions. This observed difference in H ii LFs can be explained by evolutionary effects: H ii regions in the interarm region are relatively older than those in the other parts of M51.