Hoch K K W, Rowland M, Petrus S, Nasedkin E, Ingebretsen C, Kammerer J, Perrin M, D'Orazi V, Balmer W O, Barman T, Bonnefoy M, Chauvin G, Chen C, De Rosa R J, Girard J, Gonzales E, Kenworthy M, Konopacky Q M, Macintosh B, Moran S E, Morley C V, Palma-Bifani P, Pueyo L, Ren B, Rickman E, Ruffio J-B, Theissen C A, Ward-Duong K, Zhang Y
Space Telescope Science Institute, Baltimore, MD, USA.
The University of Texas at Austin, Austin, TX, USA.
Nature. 2025 Jul;643(8073):938-942. doi: 10.1038/s41586-025-09174-w. Epub 2025 Jun 10.
Young exoplanets provide an important link between understanding planet formation and atmospheric evolution. Direct imaging spectroscopy allows us to infer the properties of young, wide-orbit, giant planets with high signal-to-noise ratio. This allows us to compare this young population with exoplanets characterized by transmission spectroscopy, which has indirectly revealed the presence of clouds, photochemistry and a diversity of atmospheric compositions. Direct detections have also been made for brown dwarfs, but direct studies of young giant planets in the mid-infrared were not possible before James Webb Space Telescope. With two exoplanets around a solar-type star, the YSES-1 system is an ideal laboratory for studying this early phase of exoplanet evolution. Here we report the direct observations of silicate clouds in the atmosphere of the exoplanet YSES-1 c through its 9-11 µm absorption feature, and the first circumplanetary disk silicate emission around its sibling planet, YSES-1 b. The clouds of YSES-1 c are composed of either amorphous iron-enriched pyroxene or a combination of amorphous MgSiO and MgSiO, with particle sizes of ≤0.1 μm at 1 millibar pressure. We attribute the emission from the disk around YSES-1 b to be from submicron olivine dust grains, which may have formed through collisions of planet-forming bodies in the disk.
年轻的系外行星为理解行星形成与大气演化之间提供了重要联系。直接成像光谱学使我们能够推断年轻、宽轨道、气态巨行星的属性，且具有高信噪比。这使我们能够将这一年轻群体与通过透射光谱学表征的系外行星进行比较，透射光谱学已间接揭示了云、光化学以及多种大气成分的存在。对褐矮星也进行了直接探测，但在詹姆斯·韦布空间望远镜之前，无法对年轻气态巨行星进行中红外的直接研究。在一颗类太阳恒星周围有两颗系外行星，YSES - 1系统是研究系外行星演化这一早期阶段的理想实验室。在此，我们报告通过其9 - 11微米吸收特征对系外行星YSES - 1 c大气中的硅酸盐云进行的直接观测，以及在其伴星YSES - 1 b周围首次观测到的环行星盘硅酸盐发射。YSES - 1 c的云由富含铁的非晶质辉石或非晶质MgSiO和MgSiO的组合构成，在1毫巴压力下粒径≤0.1微米。我们将YSES - 1 b周围盘的发射归因于亚微米级橄榄石尘埃颗粒，这些颗粒可能是通过盘中形成行星的天体碰撞形成的。
