发表机构
INAF – Osservatorio Astronomico di Padova（意大利国家天体物理研究所帕多瓦天文台）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过分析33颗太阳型恒星的圆盘演化，发现内盘尘埃质量随时间变化，并在2-5百万年恒星中观测到厘米级颗粒耗竭，为巨行星形成时代提供了观测证据。
AI 中文摘要
圆盘演化决定了行星形成的时间，为构建行星核提供了原材料。由圆盘气体运动学推导出的动力学恒星质量，为非常年轻恒星的年龄提供了约束，为研究圆盘演化和巨行星形成时代提供了一种强有力的方法。我们研究了包含33颗具有明亮原行星盘、年龄在1至9百万年之间的太阳型恒星的样本。我们同时建模了光谱能量分布和ALMA尘埃连续谱图像，以约束恒星半径和有效温度、吸积率、圆盘尘埃质量、内盘和外盘区域的半径（大致在冰线处划分）以及内盘最大颗粒尺寸。结合恒星质量和半径与恒星演化模型，我们推导出了每颗恒星的个体年龄。我们发现吸积率和内盘尘埃质量随时间演化。对于年龄小于2百万年的恒星，内盘尘埃质量与观测到的吸积率相关。在超过一半年龄在2至5百万年之间的被分析恒星中，观测到内盘中厘米级颗粒的耗竭，这表明存在一种抑制大颗粒向内漂移的机制，可能与质量大于30个地球质量的巨行星核的逐渐增长有关，尽管确切的质量阈值仍不确定。此外，三个在ALMA连续谱发射中表现出强烈不对称性的圆盘，与年龄约为2百万年的恒星相关。这些结果为巨行星可能正在形成的时代中尘埃分布的显著变化提供了观测证据。
英文摘要
Disc evolution dictates the time for planet formation providing the raw material to build the planets' cores. Dynamical stellar masses derived from the kinematics of the gas in discs provide constraints on the ages of very young stars, offering a powerful approach to studying disc evolution and the epoch of giant-planet formation. We investigated a sample of 33 solar-type stars with bright protoplanetary discs and ages between 1 and 9\,Myr. We modeled the spectral energy distributions and ALMA dust continuum images simultaneously to constrain the stellar radius and effective temperature, accretion rate, disc dust mass, the radii of the inner and outer disc regions (roughly separated at the ice line), and the maximum grain size in the inner disc. Combining the stellar masses and radii with stellar evolutionary models, we derived individual stellar ages. We found that the accretion rate and the dust mass of the inner disc evolve with time. The dust mass of the inner disc correlates with the observed accretion rates for stars younger than 2\, Myr. A depletion of centimetre-sized grains in the inner disc is observed in more than half of the analysed stars with ages between 2 and 5\, Myr indicating the action of a mechanism that inhibits the inward drift of large grains, potentially associated with the progressive growth of giant-planet cores more massive than 30 \MEarth, although the exact mass threshold remains uncertain. In addition, three discs exhibiting strong asymmetries in their ALMA continuum emission are associated with stars with ages of $\sim$2\, Myr. The results provide observational indications of significant changes in the dust distribution during the epoch when giant planets may be forming.
Comments16 pages plus 5 Appendixes. 14 Figures in the main text
