Science News内容：

题目：A Giant Disk Galaxy Two Billion Years After The Big Bang

摘要：Observational studies showed that galaxy disks are already in place in the first few billion years of the universe. The early disks detected so far, with typical half-light radii of 3 kiloparsecs at stellar masses around 10^11M⊙ for redshift z ∼ 3, are significantly smaller than today’s disks with similar masses, in agreement with expectations from current galaxy models. Here, we report observations of a giant disk at z = 3.25, when the universe was only 2 billion years old, with a half-light radius of 9.6 kiloparsecs and stellar mass of 3.7*10^11M⊙. This galaxy is larger than any other kinematically-confirmed disks at similar epochs and surprisingly similar to today’s largest disks regarding size and mass. 

报告人：彭昊（紫台研究生） 

Journal club内容：

题目：A machine learning classification of meteorite spectra applied to understanding asteroids

摘要：要了解太阳系内物质的分布，需要一种可靠的方法来评估小行星带中小物体的组成。现有的小行星分类方法不同地是基于与矿物学相关的光谱特征，或者仅仅基于小行星光谱的分类。该项目测试了一种完全不同的方法，使用机器学习算法根据现有陨石类别的光谱特征对小行星进行分类。在评估了四种基于标记陨石光谱数据的分类技术后，确定了逻辑回归(LR)提供最准确的结果，以区分八组可靠的陨石类别，然后将小行星光谱与之匹配。这些分类根植于矿物组成，并将陨石与潜在的宿主直接联系起来。一种独立的LR算法将未知小行星光谱唯一地分类为8组之一，从而可以评估小行星带中成分的分布。

报告人：李路子豪（紫台研究生）

时间：2024年12月3日星期二12:15

地点：紫台3-302