PDS 70 is one of the most interesting objects for planetary formation, with its structured dust disc and the presence of two giant accreting protoplanets embedded in its gap at 20 and 34 au. Hyerin Jang and co-workers use a combination of observations from space telescopes and modelling to have a closer look at the dusty inner part of the disc.

The authors analyse JWST/MIRI data, comparing them with archival Spitzer observations taken 15 years earlier, which overlap between approximately 5 and 27 µm. The two spectra exhibit similar shapes, with a strong 10 µm silicate band and forsterite bands at 16 and 19 µm, plus a weaker feature at 23 µm visible especially in the MIRI data. However, they show significant flux variability: if the 10 µm peak has similar intensity to the 19 µm one in Spitzer, it is almost double in MIRI. The Dust Continuum Kit (DuCK) fitting model is then used to identify the mineral components of the inner disc dust. Warm amorphous Mg-rich silicates, with a temperature between 350 and 500 K and approximately 10% iron content, dominate, but enstatite — an important component of various other inner discs — is undetected.

PDS 70 是行星形成过程中最有趣的天体之一，它具有结构化的尘埃盘，并且在 20 和 34 个天文单位的间隙中嵌入了两颗巨大的吸积原行星。 Hyerin Jang 和同事结合使用太空望远镜的观测和建模来更仔细地观察圆盘布满灰尘的内部部分。

作者分析了 JWST/MIRI 数据，将其与 15 年前的斯皮策档案观测数据进行比较，这些观测数据的重叠范围约为 5 至 27 µm。两个光谱表现出相似的形状，在 10 µm 硅酸盐带和 16 µm 和 19 µm 处有镁橄榄石带，再加上 23 µm 处较弱的特征，特别是在 MIRI 数据中可见。然而，它们显示出显着的通量变化：如果 10 µm 峰的强度与 Spitzer 中的 19 µm 峰的强度相似，则 MIRI 中的强度几乎是其两倍。然后使用灰尘连续体套件 (DuCK) 配件模型来识别内盘灰尘的矿物成分。温度在 350 至 500 K 之间、铁含量约为 10% 的温暖无定形富镁硅酸盐占主导地位，但顽辉石（各种其他内盘的重要组成部分）却未被发现。