近日，英国圣安德鲁斯大学Ryan J. MacDonald团队报道了一颗白矮星大气中的气溶胶和碳氢化合物。2026年7月1日出版的《自然》杂志发表了这项成果。

包括太阳在内的大多数恒星，终有一天会演化为红巨星，随后成为白矮星。近年来已在绕白矮星运行的轨道上发现了数颗行星候选体，表明行星能够在恒星主序后阶段完整地存留下来。然而，关于主序后行星的大气成分，人们知之甚少——迄今已进行大气探测的演化程度最高的凌星行星，仍绕亚巨星运行。

研究组报告了白矮星行星WD 1856 b的大气探测结果，该结果是通过詹姆斯·韦伯太空望远镜（JWST）近红外光谱仪（NIRSpec）PRISM模式的透射光谱获得的。该0.5–5.0 μm光谱揭示了烃类（几率比为167:1至5,377:1，其中CH₄的偏好比为17:1至30:1）、气溶胶（2×10⁵:1至2×10⁶:1）以及来自行星夜面的热辐射（2×10⁶³:1至2×10⁷³:1）的存在。通过光谱分析，研究组将WD 1856 b的质量约束在4.3–10.9倍木星质量范围内，发现其大气富碳（CH₄丰度约为7%），且有效温度（390–412 K）远超预期的行星平衡温度（160 K）。

基于冷却模型，这些结果表明WD 1856 b在白矮星阶段经历了持续3.0–5.5 Gyr的迁移相关再加热事件，这与主序后潮汐演化至现今0.02天文单位的圆轨道相一致。该研究结果为了解类太阳质量恒星周围巨行星的最终命运提供了一个窗口。

附：英文原文

Title: Aerosols and hydrocarbons in the atmosphere of a white dwarf planet

Author: MacDonald, Ryan J., OConnor, Christopher E., Boehm, Victoria A., May, E. M., Sing, David K., Mullens, Elijah, Mayorga, L. C., Foote, Trevor O., Blouin, Simon, Pearce, Logan A., Lewis, Nikole K., Valenti, Jeff, Batalha, Natasha E., Lally, Maura, Lothringer, Joshua D., Marley, Mark S., Mishra, Ishan, Mullally, Susan E.

Issue&Volume: 2026-07-01

Abstract: Most stars, including our Sun, will one day evolve into red giants and, subsequently, white dwarfs. Several planet candidates have recently been identified orbiting white dwarfs1,2,3,4, demonstrating that planets can survive the stellar post-main-sequence stage intact. Little is known about the atmospheric composition of post-main-sequence planets, with the most evolved transiting planets with atmospheric detections so far orbiting subgiants5,6. Here we report an atmospheric detection for the white dwarf planet WD1856b, achieved through transmission spectroscopy with the James Webb Space Telescope (JWST) Near-Infrared Spectrograph (NIRSpec) PRISM. Our 0.5–5.0-μm spectrum reveals the presence of hydrocarbons (odds ratio of 167:1–5,377:1, with CH4 preferred at 17:1–30:1), aerosols (2×105:1–2×106:1) and thermal emission from the planetary nightside (2×1063:1–2×1073:1). Our spectral analysis constrains the mass of WD1856b to 4.3–10.9MJ, finds a carbon-enriched atmosphere (with a CH4 abundance of approximately 7%) and an effective temperature exceeding the expected planetary equilibrium temperature (390–412K versus 160K). On the basis of cooling models, these results indicate that WD1856b underwent a migration-related reheating event 3.0–5.5Gyr into the white dwarf phase, consistent with post-main-sequence tidal evolution to the present-day 0.02-au circular orbit. Our results provide a window into the ultimate fate of giant planets orbiting stars with masses similar to our Sun.

DOI: 10.1038/s41586-026-10514-7

Source: https://www.nature.com/articles/s41586-026-10514-7