标题： 通过宜居世界观测站研究原行星和原行星盘 显示英文标题

标题： Studying Protoplanets and Protoplanetary Disks with the Habitable Worlds Observatory

摘要： 自发现第一颗围绕类太阳恒星运行的系外行星以来，过去三十年中，目前已确认近6000颗系外行星及其多样性彻底改变了我们对行星系统的认知。 然而，这些行星中的大多数围绕着成熟的恒星（${\gtrsim}1$Gyr），其中行星诞生环境已经消散。 事实上，我们仅确认了2颗形成中的行星（即原行星；${\lesssim}10$Myr），它们位于单一系统中。 相比之下，过去十年中我们已经成像了超过200个原行星盘，其中许多盘具有螺旋结构和空隙等次结构，这表明存在原行星。 为了理解行星形成的早期阶段，宜居世界观测站（HWO）——凭借其高对比度成像和积分场光谱能力——提供了一个独特的机会来探索行星形成的原始阶段及其诞生环境。 我们提议使用HWO通过直接成像来成像具有次结构的原行星盘中的原行星，并利用积分场光谱和光谱偏振技术对其进行表征（即原行星、原行星盘、原行星环）。 这项工作将大幅扩展当前原行星的样本，探测和表征超过200颗原行星。 通过将原行星数量扩大两个数量级，这些观测将检验并完善行星形成理论和行星-盘相互作用理论，并进一步推动与现有成熟行星相关的行星迁移研究。 这些结果将为行星系统形成和演化提供关键见解，并有助于理解我们自身太阳系的起源。 显示英文摘要

摘要： Since the discovery of the first exoplanet orbiting a Sun-like star, the confirmation of nearly 6000 exoplanets to date - and their diversity - has revolutionized our knowledge of planetary systems in the past three decades. Nevertheless, the majority of these planets are around mature stars (${\gtrsim}1$ Gyr), where the planet birth environments have already dissipated. Indeed, we have only confirmed 2 forming planets (i.e., protoplanets; ${\lesssim}10$ Myr) residing in one single system. In comparison, we have imaged over 200 protoplanetary disks in the past decade, with many of them hosting substructures such as spirals and gaps which suggest the existence of protoplanets. To understand the early stages of planet formation, the Habitable Worlds Observatory (HWO) - with its high-contrast imaging and integral field spectroscopy capabilities - presents a unique opportunity to explore the demographics of the natal stages of planet formation and their birth environments. We propose to image protoplanets within substructured protoplanetary disks using HWO via direct imaging, and characterize them (i.e., protoplanets, protoplanetary disks, circumplanetary disks) using integral field spectroscopy and spectropolarimetry. This effort will dramatically extend current population of protoplanets, probing and characterizing over 200 protoplanets. By expanding the number of protoplanets by two orders of magnitude, these observations will test and refine planet formation theory and planet-disk interaction theory, and further motivate planet migration studies together with existing mature planets. The results will offer critical insight into planetary system formation and evolution, and help understand the origin of our own Solar System.