To disentangle the different competing physical processes at play in Galactic evolution, a detailed chrono chemicalkinematical, and dynamical characterisation of the disc bimodality is necessary, including high number statistics. Here we make use of an extremely precise subsample of the Gaia DR3 GSP-Spec catalogue of stellar chemophysical parameters. The selected database is composed of 408 800 stars with a median uncertainty of 10 K, 0.03 and 0.01 dex in Teff , log(g) and [M/H], respectively. The stellar parameter precision allows to break the age-metallicity degeneracy of disc stars. For the first time, the disc bimodality in the Kiel diagramme of giant stars is observed, getting rid of interstellar absortion issues. This bimodality produces double Red Giant Branch sequences and Red Clump features for mono-metallicity populations. A comparison with BaSTI isochrones allows to demonstrate that an age gap is needed to explain the evolutionary sequences separation, in agreement with previous age-metallicity relations obtained using sub-giant stars. A bimodal distribution in the stellar mass-[alpha/Fe] plane is observed at constant metallicity. Finally, a selection of stars with [M/H]=0.45 \pm 0.03 dex shows that the most metal-rich population in the Milky Way disc presents an important proportion of stars with ages in the range 5-13 Gyr. This old, extremely metal-rich population is possibly a mix of migrated stars from the internal Galactic regions, and old disc stars formed before the last major merger of the Milky Way. The Gaia GSP-Spec Kiel diagrammes of disc mono-abundance stellar populations reveal a complex, non linear age-metallicity relation crafted by internal and external processes of Galactic evolution. Their detailed analysis opens new opportunities to reconstruct the puzzle of the Milky Way disc bimodality.
Emission line star catalogues post-Gaia DR3: A validation of Gaia DR3 data using LAMOST OBA emission catalogue
盖亚DR 3和进一步的释放有可能识别和分类银河系中的新发射线恒星。利用LAMOST OBA发射星表中的发射线恒星参数,对Gaia DR 3的天体物理参数进行了全面的验证。我们比较不同的天体物理参数提供的盖亚DR 3与LAMOST光谱估计。通过使用更大的发射线恒星样本,我们执行全局多项式和分段线性拟合来更新经验关系,以将Gaia DR 3伪等效宽度转换为观测到的等效宽度,然后从分析中去除弱发射体。我们发现DR 3给出的发射线源分类与LAMOST OBA发射目录的分类是一致的。与gspphot和gspspec相比,Gaia DR 3的esphs模块估计的天体物理参数提供了更好的估计。提供了二次多项式关系以及用于等效宽度转换的分段线性拟合参数。我们注意到,具有弱Hα发射的LAMOST星在BP/RP谱中没有被识别为处于发射状态。这表明盖亚DR 3识别的发射线源是不完整的。此外,盖亚DR 3提供了关于发射线恒星样本的二元和可变性质的宝贵信息。
Mapping the Galactic disk with the LAMOST and Gaia Red clump sample: I: precise distances, masses, ages and 3D velocities of $\sim$ 140000 red clump stars
An Ultraviolet-Optical Color-Metallicity relation for Red Clump Stars using GALEX and Gaia
虽然核心燃烧氦的红色团簇(RC)恒星在紫外线波长下很微弱,但它们的紫外光颜色是一种独特且可获得的物理性质探测器。利用GALEX全天成像巡天、Gaia数据发布2和SDSS APOGEE DR 14巡天的数据,我们发现光谱金属丰度与RC星在紫外光学色星等图中的位置密切相关。与(G $_{BP}$- G $_{RP}$)$_0$中的0.7星等范围相比,RC在(NUV-G)$_0$颜色中具有超过4星等的宽范围.我们提出了一个光度计,尘埃校正,紫外光学(NUV-G)$_0$颜色金属丰度[Fe/H]关系使用的5,175个RC星的APOGEE样本。我们发现,这种关系有一个0.28德克斯的散射,更容易获得大,宽场样品比光谱金属丰度。重要的是,这种效果可能与其他研究中归因于消光的RC颜色的扩散相当。
The Blanco DECam Bulge Survey (BDBS) VIII: Chemo-kinematics in the southern Galactic bulge from 2.3 million red clump stars with Gaia DR3 proper motions
Testing the asteroseismic estimates of stellar radii with surface brightness-colour relations and {\it Gaia} DR3 parallaxes. II. Red giants and red clump stars from the {\it Kepler} catalogue
Unveiling the Sagittarius Dwarf Spheroidal Galaxy Core with Gaia DR3: A Red Clump Distance Precise to 2%
The University of Texas at Austin(德克萨斯大学奥斯汀分校);Whitman College(惠特曼学院);Institute for Astronomy, University of Hawai‘i(夏威夷大学天体物理研究所);Texas Christian University(得克萨斯基督教大学);Maunakea Spectroscopic Explorer, Canada-France-Hawaii-Telescope(莫纳克亚光谱巡天项目,加拿大法国夏威夷望远镜)
Mapping the Galactic disk with the LAMOST and Gaia Red clump sample. VI: An evidence for the long lived non-steady warp of non-gravitational scenarios
结合LAMOST DR 4和Gaia DR 2普通红团簇星的年龄和自行,我们用一个简单的模型分析了不依赖于任何假设的恒星翘曲幅度的演化。不同星族的最大翘曲盘高度随银心距的增大而增大,并与年龄有关:年轻恒星星族的翘曲特征比老星族强,翘曲振幅$γ({\rm age})$随年龄减小,其一阶导数$\dotγ ({\rm age})$不等于零.节点线方位角$ϕ_w$稳定在$-$ 5 °,没有明显的时间演化,这很好地证实了前人的一些工作。所有这些自洽的证据都支持我们的银河系弯曲应该是一个长期存在的,但非稳定的结构,而不是一个短暂的,这是支持弯曲是起源于气体落入磁盘或其他假设,认为弯曲主要影响到气体,因此年轻的人口跟踪气体比老的更强。换句话说,银河系翘曲是由盘模型上的非引力相互作用引起的。
Mapping the Galactic disk with the LAMOST and Gaia Red clump sample: III: A new velocity substructure and time stamps of the Galactic disk asymmetry in the disk between 12$-$15 \,kpc
Mapping the Galactic disk with the LAMOST and Gaia Red clump sample. II. 3D asymmetrical kinematics of mono-age populations in the disk between 6$-14$ \,kpc
我们进行分析的三维运动学的银河系盘星在单年龄人口。从LAMOST DR 4红团巨星和Gaia DR 2自行星表中选取银心距离在$R=6$和14 kpc之间的恒星。我们证实了最近工作的三维非对称运动,并提供了银心距离为14,kpc的反中心方向附近的银河系外盘非对称运动的时间标记。径向银心运动的值达到10公里秒$^{-1}$,这取决于人口的年龄,并提出了一个南北不对称的区域对应的密度和速度的子结构,是敏感的扰动在早期6 \,Gyr。在那之后,在这种不对称结构中的盘星在运动学上变得更热,因此对扰动不敏感,我们发现这种结构是一个相对年轻的种群。通过定量分析,我们发现在平面之上和之下的$R\gtrsim 9$ kpc处的恒星都表现出弯曲模运动,其敏感持续时间约为8 \,Gyr。我们推测,面内不对称可能主要是由快速旋转的酒吧,本质上椭圆形的外盘,长期膨胀的磁盘,或流。螺旋臂动力学、不平衡模型、小型兼并或其他因素都是重要的贡献者。垂直运动可能由复杂的内部或外部扰动引起的弯曲和呼吸模式主导。这些机制中有许多可能是相互关联的。
Mapping the Galactic disk with the LAMOST and Gaia Red clump sample: VIII: Mapping the kinematics of the Galactic disk using mono-age and mono-abundance stellar populations
Mapping the Milky Way with Gaia Bp/Rp spectra-IV: the broken and asymmetric density profile of the stellar disk traced by a large sample of red clumps
Institute of Astronomy and Physics, Inner Mongolia University(内蒙古大学天文与物理学院);National Astronomical Observatories, Chinese Academy of Sciences(中国科学院国家天文台);Instituto de Astrofísica de Canarias(加那利天体物理研究所);Universidad de La Laguna(拉各纳大学);School of Astronomy and Space Science, University of Chinese Academy of Sciences(中国科学院大学天文与空间科学学院);Key Laboratory of Survey Science of Yunnan Province, Yunnan University(云南省测绘科学重点实验室)
Planck Galactic Cold Clumps at High Galactic Latitude-A Study with CO Lines
银河系高纬度的气体是星际介质中相对较少注意的成分。为了解决这个问题,利用紫金山天文台13.7米望远镜在银河系高纬度(HGal; $|b|>25^{\circ}$)观测到41个普朗克银河系冷团,它们位于$^{12}$ CO、$^{13}$ CO和C $^{18}$ O J=1-0谱线上。$^{12}$ CO(1-0)和$^{13}$ CO(1-0)的发射在所有的团块中被检测到,而C $^{18}$ O(1-0)的发射仅见于16个团块中。最高纬度和平均纬度分别为$71.4^{\circ}$和$37.8^{\circ}$。获得了51个速度分量,然后将每个分量识别为单个团块。在1 $^\prime$分辨率下进一步绘制了33个团块,并提取了54个致密岩心。在致密核中,$^{12}$ CO的平均激发温度$T_{\mathrm{ex}}$为10.3K.热和非热速度色散的平均线宽分别为$0.19$ km s $^{-1}$和$0.46$ km s $^{-1}$,表明这些核心是由湍流主导的。由盖亚尘埃红化给出的HGal团块的距离约为$120-360$ pc。$X_{13}$ / $X_{18}$的比值明显高于太阳附近的比值,这意味着HGal气体与银河系盘中的气体相比具有不同的恒星形成历史。从$0.01-0.1$ pc大小的HGal核心没有显示出明显的Larson关系,并且湍流保持超音速直到略低于$…
High-fidelity stellar extinction with Gaia and APOGEE -- I. The method and a new extinction curve
Nanjing University(南京大学);Key Laboratory of Modern Astronomy and Astrophysics, Ministry of Education(现代天文与天体物理教育部重点实验室);Australian National University(澳大利亚国立大学);Kavli Institute for Particle Astrophysics & Cosmology (KIPAC), Stanford University(斯坦福大学卡弗里粒子天体物理学与宇宙学研究所);INAF - Osservatorio Astrofisico di Torino(意大利国家天体物理研究所都灵天文台)