Usually, important parameters of young, low-mass star clusters are very difficult to obtain by means of photometry, especially when differential reddening and/or binaries occur in large amounts. We present a semi-analytical approach that, applied to the Hess diagram of a young star cluster, is able to retrieve the values of mass, age, star-formation spread, distance modulus, foreground and differential reddening, and binary fraction. The global optimisation method known as adaptive simulated annealing (ASA) is used to minimise the residuals between the observed and simulated Hess diagrams of a star cluster. The simulations are realistic and take the most relevant parameters of young clusters into account. Important features of the simulations are: a normal (Gaussian) differential reddening distribution, a time-decreasing star-formation rate, the unresolved binaries, and the smearing effect produced by photometric uncertainties on Hess diagrams. Free parameters are: cluster mass, age, distance modulus, star-formation spread, foreground and differential reddening, and binary fraction.
Carbon Stars as Standard Candles: An Empirical Test for the Reddening, Metallicity, and Age Sensitivity of the J-region Asymptotic Giant Branch (JAGB) Method
Unveiling Metal Mixing in a Grand-Design Spiral: A UV-optical multiphase spatially resolved study of M83
Space Telescope Science Institute（太空望远镜科学研究所）；European Space Agency (ESA)（欧洲空间局）；AURA for the European Space Agency（欧洲空间局美国大学研究协会）；Astrophysics Division, Science Mission Directorate, NASA Headquarters（美国国家航空航天局总部科学任务 Directorate 天体物理学部）
On a new method to estimate distance, reddening and metallicity of RR Lyrae stars using optical/near-infrared ($B$,$V$,$I$,$J$,$H$,$K$) mean magnitudes: $ω$ Centauri as a first test case
Unveiling Long-Period Variables in M33's Central Region: Insights into Stellar Evolution and Star Formation via Near-Infrared Photometry
University of Zanjan（赞詹大学）；Institute for Research in Fundamental Sciences (IPM)（伊朗基础科学研究院）；Center for Research in Climate Change and Global Warming (CRCC), IASBS（赞詹伊斯兰阿扎德大学气候变化与全球变暖研究中心）；HUN-REN Research Centre for Astronomy and Earth Sciences（匈牙利研究与创新网络天文学与地球科学研究中心）
Chronology of our Galaxy from Gaia colour-magnitude diagram fitting (ChronoGal) II. Unveiling the formation and evolution of the kinematically selected Thick and Thin Discs
Universidad de La Laguna（拉古纳大学）；Instituto de Astrofísica de Canarias（加那利天体物理学研究所）；University of Granada（格拉纳达大学）；INAF – Astronomical Observatory of Abruzzo（意大利国家天体物理研究所阿布鲁佐天文台）；INFN, Sezione di Pisa（意大利国家核物理研究所比萨分部）；Kapteyn Astronomical Institute, University of Groningen（格罗宁根大学卡普坦天文研究所）
模糊和混乱合在一起限制了我们对银河系内部的了解。即使在中等距离，恒星系统的识别也会因背景源的密度极高而变得复杂。在这里，我们提供了一个非常揭示这些复杂性的例子，揭示了一个巨大的，巨大的，年轻的星团在人马座臂，一直逃脱检测到现在，尽管包含30多颗恒星比$G=13$亮。结合Gaia DR 2天体测量、Gaia和2 MASS测光和光谱学，我们发现这个位于$\sim2.3\:$ kpc的新星团，我们将其命名为Valparaiso 1，年龄约75 Ma，包含大量的演化恒星，其中我们重点介绍了4d经典造父变星CM Sct和一颗M型巨星，这可能是在银河系年轻疏散星团中首次发现AGB星。虽然强烈的微分红化使得精确的参数确定不可行，直接比较类似年龄的星团表明，瓦尔帕莱索~1是太阳邻域中质量最大的星团之一，初始质量接近$10^{4}\:$ M $_{\odot}$。
Models for Metal-Poor Stars with Different Initial Abundances of C, N, O, Mg, and Si. II. Application to the Colour-Magnitude Diagrams of the Globular Clusters 47 Tuc, NGC 6362, M5, M3, M55, and M92
我们用HST Wide Field Camera 3（WFC 3）对球状星团（GC）47 Tuc、NGC 6362、M5、M5、M55和M92的观测结果，比较了在C：N：O丰度比（[CNO/Fe]的两个不同值）变化下计算的-2.5 <= [Fe/H] <= -0.5的恒星模型。用于将模型转置到观察平面的测辐射热校正是基于新的MARCS合成光谱，该合成光谱结合了对涉及C、N和O原子的分子的改进处理。在距离模量和红度得到充分支持的假设下，其他α元素的[O/Fe] = 0.6和[m/Fe] = 0.4的等时线（这是GC中双星所青睐的）通常再现了观测到的颜色星等图（CMD）的主要特征，误差在~ 0.03 mag.它们似乎与观测到的（M_F336 W-M_F438 W）_0颜色的分布很好地匹配，这些颜色由CN-弱和CN-强恒星沿低巨星分支跨越，但不是最蓝的巨星，它们被怀疑是贫N的（[N/Fe] <~ -0.5）。无论是（M_F438 W-M_F606 W）_0的绝对颜色，还是在给定的M_F606W星等上这些颜色的变化，都很难解释，除非最红的恒星是富C的（[C/Fe] >~ +0.5）。允许适度的He丰度变化（Δ Y ~ 0.05）改善了对观测的拟合。
