SURVEYING THE AGENTS OF GALAXY EVOLUTION IN THE TIDALLY STRIPPED, LOW METALLICITY SMALL MAGELLANIC CLOUD (SAGE-SMC). II. COOL EVOLVED STARS-猫眼课题宝

DOI：

10.1088/0004-6256/142/4/103

发表时间：

2011-06

期刊：

The Astronomical Journal

影响因子：

通讯作者：

中科院分区：

其他

文献类型：

作者：

M. Boyer;S. Srinivasan;J. V. Loon;I. McDonald;M. Meixner;D. Zaritsky;K. Gordon;F. Kemper;F. Kemper;B. Babler;M. Block;S. Bracker;C. Engelbracht;J. Hora;R. Indebetouw;M. Meade;K. Misselt;T. Robitaille;M. Sewiło;B. Shiao;B. Whitney;B. Whitney

我们研究了小麦哲伦星云(SMC)中冷却的演化恒星的红外(IR)特性，包括红巨星分支(RGB)恒星和产生尘埃的红超巨星(RSG)和渐近巨星分支(AGB)恒星。这项调查首次包括在红外波长(3.6160μm)下对SMC条、翼和尾部区域的全空间覆盖。我们使用近红外和中红外光度学相结合的方法来识别演化恒星，并指出了中红外颜色-星等图中的一个新特征，这可能是由于特别尘埃的富氧AGB恒星。我们发现RSG星和AGB星各自贡献了全球SMC通量的20%(扩展+点源)，≈为3.6μm，这强调了这两种恒星类型对遥远的贫金属星系的积分通量的重要性。高金属度大麦哲伦星云(SAGE-LMC)的等效SAGE测量使我们能够探索金属度对尘埃产生的影响。我们发现，SMC RSG恒星不太可能产生大量的尘埃(如[3.6]−[8]颜色所示)。SMC中富碳恒星的比例较高，这些恒星的颜色似乎与LMC对应的恒星一样红，这表明两个星系中都有效地形成了富碳尘埃。对AGB和RSG星尘埃产生的初步估计表明，这两个星系的尘埃输入主要是极富C的AGB星，富O星在LMC中可能比在SMC中起到更大的作用。

We investigate the infrared (IR) properties of cool, evolved stars in the Small Magellanic Cloud (SMC), including the red giant branch (RGB) stars and the dust-producing red supergiant (RSG) and asymptotic giant branch (AGB) stars using observations from the Spitzer Space Telescope Legacy program entitled “Surveying the Agents of Galaxy Evolution in the Tidally Stripped, Low Metallicity SMC,” or SAGE-SMC. The survey includes, for the first time, full spatial coverage of the SMC bar, wing, and tail regions at IR wavelengths (3.6–160 μm). We identify evolved stars using a combination of near-IR and mid-IR photometry and point out a new feature in the mid-IR color–magnitude diagram that may be due to particularly dusty O-rich AGB stars. We find that the RSG and AGB stars each contribute ≈20% of the global SMC flux (extended + point-source) at 3.6 μm, which emphasizes the importance of both stellar types to the integrated flux of distant metal-poor galaxies. The equivalent SAGE survey of the higher-metallicity Large Magellanic Cloud (SAGE-LMC) allows us to explore the influence of metallicity on dust production. We find that the SMC RSG stars are less likely to produce a large amount of dust (as indicated by the [3.6] − [8] color). There is a higher fraction of carbon-rich stars in the SMC, and these stars appear to reach colors as red as their LMC counterparts, indicating that C-rich dust forms efficiently in both galaxies. A preliminary estimate of the dust production in AGB and RSG stars reveals that the extreme C-rich AGB stars dominate the dust input in both galaxies, and that the O-rich stars may play a larger role in the LMC than in the SMC.

SURVEYING THE AGENTS OF GALAXY EVOLUTION IN THE TIDALLY STRIPPED, LOW METALLICITY SMALL MAGELLANIC CLOUD (SAGE-SMC). II. COOL EVOLVED STARS

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