Carbon Stars and Other Luminous Stellar Populations in M33
Carbon Stars and Other Luminous Stellar Populations in M33
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DOI：
10.1086/427247
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发表时间：
2004-11
期刊：
影响因子：
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通讯作者：
J. Rowe;J. Rowe;H. Richer;H. Richer;J. Brewer;J. Brewer;D. Crabtree;D. Crabtree
中科院分区：
文献类型：
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作者：
J. Rowe;J. Rowe;H. Richer;H. Richer;J. Brewer;J. Brewer;D. Crabtree;D. Crabtree
M33星系是附近一个相对缺乏金属的晚型螺旋星系。它的接近性和几乎面向的倾角意味着它可以在天空上投射大片区域，使其成为宽视场CCD马赛克成像的理想候选者。在以M33为中心的74 ‘ × 56 ’的范围内，有超过106颗恒星的光度测量结果。利用宽带V和I光度法对主序、超巨星分支、红巨星分支和渐近巨星分支（AGB）种群进行了识别和分类。窄带滤光片用于测量光谱特征，从而将AGB群进一步划分为C星和M星类型。M33的星系结构是用恒星数、颜色和颜色等选择的恒星群来检查的。我们用C星与M星的比值研究了M33盘的金属丰度梯度。C/M星比随着星系中心半径的增大先增大后趋于平缓，与粘性盘形成模型一致。发现C星的光度函数与M31和SMC相似，这表明C星应该是有用的距离指示器。Block等人最近提出的M33中“碳星的壮观弧线”在我们的工作中被发现仅仅是M33圆盘的延伸。
The M33 galaxy is a nearby, relatively metal-poor, late-type spiral. Its proximity and almost face-on inclination means that it projects over a large area on the sky, making it an ideal candidate for wide-field CCD mosaic imaging. Photometry was obtained for more than 106 stars covering a 74′ × 56′ field centered on M33. Main-sequence, supergiant branch, red giant branch, and asymptotic giant branch (AGB) populations are identified and classified based on broadband V and I photometry. Narrowband filters are used to measure spectral features allowing, the AGB population to be further divided into C and M star types. The galactic structure of M33 is examined using star counts, color-color–, and color-magnitude–selected stellar populations. We use the C to M star ratio to investigate the metallicity gradient in the disk of M33. The C/M star ratio is found to increase and then flatten with increasing galactocentric radius, in agreement with viscous disk formation models. The C star luminosity function is found to be similar to M31 and the SMC, suggesting that C stars should be useful distance indicators. The "spectacular arcs of carbon stars" in M33 postulated recently by Block et al. are found in our work to be simply an extension of M33's disk.