FU Orionis–type stars are young stellar objects showing large outbursts due to highly enhanced accretion from the circumstellar disk onto the protostar. FU Orionis–type object (FUor) outbursts happen in a wide variety of sources from the very embedded ones to those with almost no sign of extended emission beyond the disk. The subsequent eruptions might gradually clear up the obscuring envelope material and drive the protostar on its way to become a disk-only T Tauri star. We used the Very Large Telescope (VLT)/VLT spectrometer and imager for the mid-infrared (VISIR) to obtain the first spectra that cover the 8–13 μ m mid-infrared wavelength range in low resolution of five recently discovered FUors. Four objects from our sample show the 10 μ m silicate feature in emission. We study the shape and strength of the silicate feature in these objects and find that they mostly contain large amorphous grains, suggesting that large grains are typically not settled to the midpl...

中文翻译：

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新发现的年轻爆发恒星的颗粒生长

FU Orionis型恒星是年轻的恒星，由于从星际盘到原恒星的吸积大大增强，显示出大爆发。FU Orionis型物体（FUor）爆发发生在各种各样的源中，从非常嵌入式的源到几乎没有扩展到磁盘之外的扩展迹象的源。随后的喷发可能会逐渐清除隐蔽的包膜物质，并推动原恒星成为仅由磁盘构成的T Tauri星。我们使用超大望远镜（VLT）/ VLT光谱仪和中红外成像仪（VISIR），获得了五个最近发现的FUor的低分辨率的第一个光谱，该光谱涵盖了8-13μm的中红外波长范围。我们样品中的四个物体显示出10μm的硅酸盐特征。