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首页> 外文期刊>The Astrophysical journal >MID-INFRARED OBSERVATION OF MASS LOSS IN ELLIPTICAL GALAXIES
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MID-INFRARED OBSERVATION OF MASS LOSS IN ELLIPTICAL GALAXIES

机译：椭圆星系中红外损失的中红外观测

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Early-type galaxies exhibit thermal and molecular resonance emission from dust that is shed and heated through stellar mass loss as a subset of the population moves through the asymptotic giant branch (AGB) phase of evolution. Because this emission can give direct insight into stellar evolution in addition to galactic stellar mass loss and interstellar medium injection rates, we conducted a program to search for this signature emission with CAM on the Infrared Space Observatory. We obtained 6-15μm imaging observations in six narrow bands for nine elliptical galaxies; every galaxy is detected in every band. For wavelengths shorter than 9μm, the spectra are well matched by a blackbody originating from the K and M stars that dominate the integrated light of elliptical galaxies. At wavelengths between 9 and 15μm, however, the galaxies display excess emission relative to the stellar photospheric radiation. Additional data taken with the fine-resolution circular variable filter on one source clearly shows broad emission from 9 to 15μm, peaking around 10μm. This result is consistent with the known broad silicate feature at 9.7μm originating in the circumstellar envelopes of AGB stars. This emission is compared with studies of Galactic and Large Magellanic Cloud AGB stars to derive cumulative mass-loss rates. In general, these mass-loss rates agree with the expected ～0.8 solar mass yr~(-1) value predicted by stellar evolutionary models. Both the photospheric and circumstellar envelope emission follow a de Vaucouleurs R~(1/4) law, supporting the conclusion that the mid-infrared excess emission originates in the stellar component of the galaxies and acts as a tracer of AGB mass loss and mass injection into the interstellar medium.
机译：早期类型的星系表现出来自尘埃的热和分子共振发射，这些尘埃通过恒星质量损失而散落并加热，这是由于一部分人口移动通过了渐近巨型分支（AGB）演化阶段。因为除了银河系恒星质量损失和星际介质注入速率外，这种辐射还可以直接了解恒星的演化，所以我们进行了一个程序，在红外空间天文台上用CAM搜索这种标志性的辐射。我们获得了9个椭圆星系在六个窄带中的6-15μm成像观测结果；每个波段都检测到每个星系。对于短于9μm的波长，光谱由一个以椭圆星系的积分光为主的K和M星形成的黑体很好地匹配。但是，在9到15μm的波长之间，相对于恒星光球辐射，星系会显示出过多的发射。在一个光源上使用高分辨率的圆形可变滤波器获取的其他数据清楚地显示出9到15μm的宽发射，峰值约为10μm。这一结果与已知的9.7μm宽硅酸盐特征相一致，该特征起源于AGB恒星的星际包壳。将该辐射与银河系和大麦哲伦星系AGB恒星的研究进行比较，得出累积质量损失率。通常，这些质量损失率与恒星演化模型预测的〜0.8太阳质量yr〜（-1）值相符。光球和星际包络发射均遵循de Vaucouleurs R〜（1/4）定律，支持以下结论：中红外过量发射起源于星系的恒星部分，并作为AGB质量损失和质量注入的示踪剂。进入星际介质。

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