We report the discovery of a young massive stellar cluster embedded in an extended H II region, invisible at optical wavelengths where the extinction is AV ≈ 28 mag, associated with the IRAS source 16177-5018. J-, H-, and narrowband K-imaging photometry combined with the Ks Two Micron All Sky Survey data show the presence of sources with excess infrared emission at 2.2 μm, concentrated in an area of about 1 pc2 around a massive young stellar object identified as the IRAS source. This object has a near mid-infrared spectral index between 2.2 and 25 μm α(IR) = d log(λFλ)/d log λ = 4.78, characteristic of compact H II regions, with bolometric luminosity inferred from the integrated near–to–far-infrared flux density of 2.8 × 105 L⊙, which corresponds to a zero-age main-sequence star of about 42 M⊙. From the color-magnitude diagram we were able to classify the majority of the cluster members as reddened massive stars earlier than spectral type B5.
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机译：我们报告发现了一个年轻的巨大恒星簇的发现，该簇嵌在一个扩展的H II区中，在消光为AV≈28 mag的光波长处不可见，与IRAS源16177-5018相关。 J，H和窄带K成像光度法与Ks两微米全天候测量数据相结合，显示存在2.2μm的红外辐射过多的光源，这些光源集中在大约1 pc2的区域内，该区域位于已识别的巨大年轻恒星物体周围作为IRAS来源。该物体的近中红外光谱指数在2.2至25μm之间。α（IR）= d log（λFλ）/ d logλ= 4.78，具有紧凑的H II区域的特征，并且通过综合近红外光谱可以推断出辐射强度。 2.8×105L⊙的远红外通量密度，相当于约42M⊙的零年龄主序星。根据色度图，我们能够将大多数星团成员分类为比光谱类型B5更早变红的大质量恒星。
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