We present observations of three protoplanetary discs in visible scattered light around M-type stars in the Upper Scorpius OB association using the Space Telescope Imaging Spectrograph (STIS) instrument on the Hubble Space Telescope (HST). The discs around stars 2MASS J16090075–1908526, 2MASS J16142029–1906481, and 2MASS J16123916–1859284 have all been previously detected with the Atacama Large Millimeter/submillimeter Array (ALMA), and 2MASS J16123916–1859284 has never previously been imaged at scattered light wavelengths. We process our images using reference star differential imaging, comparing and contrasting three reduction techniques – classical subtraction, Karhunen–Loève Image Projection, and non-negative matrix factorization, selecting the classical method as the most reliable of the three for our observations. Of the three discs, two are tentatively detected (2MASS J16142029–1906481 and 2MASS J16123916–1859284), with the third going undetected. Our two detections are shown to be consistent when varying the reference star or reduction method used, and both detections exhibit structure out to projected distances of ≳200 au. Structures at these distances from the host star have never been previously detected at any wavelength for either disc, illustrating the utility of visible-wavelength observations in probing the distribution of small dust grains at large angular separations.

中文翻译：

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上天蝎座原行星盘的 HST/STIS 视图：对三颗年轻 M 星的观察

我们使用哈勃太空望远镜 (HST) 上的太空望远镜成像光谱仪 (STIS) 仪器在上天蝎座 OB 协会的 M 型恒星周围的可见散射光中展示了三个原行星盘的观察结果。恒星 2MASS J16090075–1908526、2MASS J16142029–1906481 和 2MASS J16123916–1859284 周围的圆盘之前都已用阿塔卡马大毫米/亚毫米阵列 (ALMA) 检测到，而 2MASS J16123916–1859284 之前从未在散射光波长下成像. 我们使用参考星差分成像处理我们的图像，比较和对比三种减少技术——经典减法、Karhunen-Loève 图像投影和非负矩阵分解，选择经典方法作为我们观察中最可靠的三种方法。三张碟中，暂时检测到两个（2MASS J16142029–1906481 和 2MASS J16123916–1859284），第三个未被检测到。当改变使用的参考星或减少方法时，我们的两个检测显示是一致的，并且两个检测都显示出投影距离 ≳200 au 的结构。之前从未在任何一个圆盘的任何波长上检测到距主星这些距离的结构，这说明了可见波长观测在探测大角间距下小尘埃颗粒分布的实用性。