AI 中文总结
利用盖亚DR3数据等确定御夫座α星、昴宿星团和毕星团的初始质量函数等特性，通过新方法结合多种算法确定相关参数，发现最佳拟合的三阶段分段幂律分布初始质量函数，为IMF特性及相关研究提供证据和限制。
AI 中文摘要
我们利用盖亚DR3天体测量和光度测量确定了疏散星团御夫座α星、昴宿星团和毕星团的初始质量函数（IMF）和结构特性。主要通过盖亚天体测量识别星团成员，并辅以近红外UKIDSS和光学HIPPARCOS巡天数据，恒星质量低至0.10 - 0.17太阳质量。我们在贝叶斯框架下使用光度测量和蒙特卡罗模拟测量并校正各星团中未分辨的双星，发现现今比例在(20.0±0.8)%至(23.8±1.2)%之间。通过一种将N体模拟与机器学习模拟器和MCMC算法相结合的新方法，在早期气体去除不显著影响后续星团演化的假设下，我们还确定了最可能的初始恒星数量、双星比例、半质量半径和质量函数。我们发现一个最佳拟合的初始质量函数由三阶段分段幂律分布描述，转折点质量在0.24 - 0.50太阳质量和0.91 - 1.20太阳质量范围内，平均斜率为α_med = 1.72±0.09和α_high = 2.98±0.22。虽然低质量斜率对采用的质量 - 光度关系仍敏感，但一旦考虑其动力学演化，该IMF能很好地再现现今星团。我们发现各星团之间高质量IMF存在散射证据，质量函数斜率的测量色散为σ_high = 0.29±0.16，而中等质量斜率无显著变化，σ_med = 0.00±0.14。我们的发现为（与萨尔皮特质量函数相比）顶部较轻IMF和IMF的星团间变化提供了额外证据，从而对IMF的普遍性及其对环境条件的依赖性提供了限制。
英文摘要
We have determined the initial mass function (IMF) and structural properties of the open clusters Alpha Persei, Pleiades and Praesepe using Gaia DR3 astrometry and photometry. Cluster members were identified using primarily Gaia astrometry, supplemented with near-infrared UKIDSS and optical HIPPARCOS survey data with stellar masses down to $0.10-0.17$ MSun. We measure and correct for unresolved binaries in each cluster using photometry and Monte Carlo simulations in a Bayesian framework, finding present-day fractions between ($20.0\pm0.8$)% and ($23.8\pm1.2$)%. Through a novel approach that combines N-body simulations with machine learning emulators and MCMC algorithms, we have also determined the most probable initial number of stars, binary fraction, half-mass radius and mass function under the assumption that early gas removal does not significantly influence the subsequent cluster evolution. We find a best-fitting initial mass function described by a three-stage broken power-law distribution with break masses in the ranges $0.24-0.50$ MSun and $0.91-1.20$ MSun and average slopes of $α_{\rm med}=1.72\pm0.09$ and $α_{\rm high}=2.98\pm0.22$. While the low-mass slope remains sensitive to the adopted mass-luminosity relation, this IMF reproduces the present-day clusters well once their dynamical evolution is taken into account. We find evidence of scatter in the high mass IMF between the individual clusters, as described by the measured dispersions in mass function slopes of $σ_{\rm high}=0.29\pm0.16$, whereas the intermediate mass slope shows no significant variation with $σ_{\rm med}=0.00\pm0.14$. Our findings provide additional evidence for a (compared to a Salpeter MF) top-light IMF and a cluster-to-cluster variation of the IMF. They therefore provide constraints on the universality of the IMF and its dependence on environmental conditions.
CommentsAccepted for publication in PASA. 27 pages, 17 figures, 7 tables
Journal refPublications of the Astronomical Society of Australia, 43, e100 (2026)
