AI 中文总结
基于JWST的NIRCam和MIRI观测数据给出NGC 6822光度目录，经系列操作得到恒星样本，用GRAMS分析样本得出尘埃产生率等，发现富氧AGB恒星贡献高，还确定了相关颜色关系可估计尘埃产生率。
AI 中文摘要
我们基于用近红外相机（NIRCam）和中红外仪器（MIRI）获得的詹姆斯·韦布空间望远镜的深度观测数据，给出了本星系群矮星系NGC 6822的光度测量目录。使用StarbugII进行点扩散函数测光和波段匹配。所得目录包含864,114个NIRCam点源和17,235个MIRI探测源，其中10,079个在两种仪器中均被探测到。黑体拟合得出119,621颗恒星的有效温度和热光度，提供了已解析恒星成分的详细视图。从NIRCam - MIRI颜色 - 星等图中选择候选演化恒星，通过去除已解析的污染物并通过光谱能量分布（SED）拟合排除年轻恒星物体来细化样本。使用红超巨星和渐近巨星分支模型网格（GRAMS）分析1226颗演化恒星的最终样本，从中获得尘埃产生率，并通过在整个模型集上的似然加权比较分配富碳或富氧渐近巨星分支（AGB）分类。在詹姆斯·韦布空间望远镜的各个区域，演化恒星向星际介质返回5.6×10^-7太阳质量/年的尘埃，尽管NGC 6822金属丰度低，但富氧AGB恒星贡献60%，富碳AGB恒星贡献35%。出乎意料的高富氧贡献表明存在经历热底燃烧的中等质量AGB恒星，这与NGC 6822最近的恒星形成历史一致。产生尘埃的AGB恒星呈现出中心集中的富碳群体和更扩展的富氧群体。我们还确定了詹姆斯·韦布空间望远镜颜色关系，这些关系为演化恒星的尘埃产生率提供了可靠的光度测量估计。
英文摘要
We present a photometric catalogue of the Local Group dwarf galaxy NGC 6822 based on deep JWST observations obtained with the Near-Infrared Camera (NIRCam) and Mid-Infrared Instrument (MIRI). Point-spread-function photometry and band matching were performed with StarbugII. The resulting catalogue contains 864,114 NIRCam point sources and 17,235 MIRI detections, with 10,079 detected in both instruments. Blackbody fitting yields effective temperatures and bolometric luminosities for 119,621 stars, providing a detailed view of the resolved stellar content. Candidate evolved stars were selected from NIRCam-MIRI colour-magnitude diagrams, with the sample refined by removing resolved contaminants and excluding young stellar objects through spectral energy distribution (SED) fitting. The final sample of 1226 evolved stars was analysed using the Grid of Red Supergiant and Asymptotic Giant Branch Models (GRAMS), from which dust-production rates were obtained and carbon-rich or oxygen-rich asymptotic giant branch (AGB) classifications assigned via a likelihood-weighted comparison across the full model set. Across the JWST fields, evolved stars return 5.6 x 10^-7 Msun yr^-1 of dust to the interstellar medium, with oxygen-rich AGB stars contributing 60% and carbon-rich AGB stars 35%, despite the low metallicity of NGC 6822. The unexpectedly high oxygen-rich contribution indicates the presence of intermediate-mass AGB stars undergoing hot-bottom burning, in line with the recent star-formation history of NGC 6822. Dust-producing AGB stars exhibit a centrally concentrated carbon-rich population and a more extended oxygen-rich population. We also identify JWST colour relations that provide robust photometric estimators of dust-production rates for evolved stars.
Comments19 pages, 14 figures. Accepted for publication in MNRAS. The accompanying catalogue contains photometry for 864,114 NIRCam sources and 17,235 MIRI sources, including derived effective temperatures and bolometric luminosities for 119,621 stars and dust-production rates for 1226 evolved stars. The catalogue will be available through VizieR upon publication
