First evidence of multi-iron sub-populations in the Bulge Fossil Fragment candidate Liller 1
Chiara Crociati, Elena Valenti, Francesco R. Ferraro, Cristina Pallanca, Barbara Lanzoni, Mario Cadelano, Cristiano Fanelli, Livia Origlia, Emanuele Dalessandro… 展开作者
Chiara Crociati, Elena Valenti, Francesco R. Ferraro, Cristina Pallanca, Barbara Lanzoni, Mario Cadelano, Cristiano Fanelli, Livia Origlia, Emanuele Dalessandro, Alessio Mucciarelli, R. Michael Rich
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Accepted for publication in the ApJ, 15 pages, 9 figures
In the context of a project aimed at characterizing the properties of the so-called Bulge Fossil Fragments (the fossil remnants of the bulge formation epoch), here we present the first determination of the metallicity distribution of Liller 1. For a sample of 64 individual member stars we used ESO- MUSE spectra to measure the equivalent width of the CaII triplet and then derive the iron abundance. To test the validity of the adopted calibration in the metal-rich regime, the procedure was first applied to three reference bulge globular clusters (NGC 6569, NGC 6440, and NGC 6528). In all the three cases, we found single-component iron distributions, with abundance values fully in agreement with those reported in the literature. The application of the same methodology to Liller 1 yielded, instead, a clear bimodal iron distribution, with a sub-solar component at $\text{[Fe/H]}= -0.48\,$dex ($σ= 0.22$) and a super-solar component at $\text{[Fe/H]}= +0.26\,$dex ($σ= 0.17$). The latter is found to be significantly more centrally concentrated than the metal-poor population, as expected in a self-enrichment scenario and in agreement with what found in another bulge system, Terzan 5. The obtained metallicity distribution is astonishingly similar to that predicted by the reconstructed star formation history of Liller 1, which is characterized by three main bursts and a low, but constant, activity of star formation over the entire lifetime. These findings provide further support to the possibility that, similar to Terzan 5, also Liller 1 is a Bulge Fossil Fragment.
Is the Nuclear Star Cluster a Bulge Fossil Fragment?
University of California, Los Angeles（加州大学洛杉矶分校）；Lund University（隆德大学）；Université Côte d’Azur（蔚蓝海岸大学）；Observatoire de la Côte d’Azur（蔚蓝海岸天文台）；CNRS（法国国家科学研究中心）；Laboratoire Lagrange（拉格朗日实验室）；Space Telescope Science Institute（太空望远镜科学研究所）
Bulge Fossil Fragments as a new population of factories of gravitational wave sources in the Galaxy
Università degli Studi di Bologna（博洛尼亚大学）；INAF, Osservatorio di Astrofisica e Scienza dello Spazio di Bologna（意大利国家天体物理研究所博洛尼亚天文与空间科学观测站）；Dept. of Astronomy, Indiana University（印第安纳大学天文学系）
Discovery of over a thousand variable stars in Terzan 5 and Liller 1 with JWST
Massachusetts Institute of Technology（麻省理工学院）；Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology（麻省理工学院卡弗里天体物理学与空间研究研究所）；Institute of Science and Technology Austria (ISTA)（奥地利科学技术研究院）；Dipartimento di Fisica e Astronomia “Augusto Righi”, Università di Bologna（博洛尼塔大学物理与天文学系）；INAF – Osservatorio di Astrofisica e Scienza dello Spazio di Bologna (OAS)（意大利国家天体物理研究所博洛尼亚天文与空间科学观测站）；Center for Astrophysics — Harvard & Smithsonian（哈佛-史密森天体物理中心）
The properties of central stellar knots embedded in galactic bulges of CIELO simulations
Pontificia Universidad Católica de Chile（智利天主教 Pontificia 大学）；Instituto de Astrofísica, Pontificia Universidad Católica de Chile（智利天主教 Pontificia 大学天体物理研究所）；Centro de AstroIngeniería, Pontificia Universidad Católica de Chile（智利天主教 Pontificia 大学天文工程中心）；Instituto de Astronomía y Física del Espacio, CONICET-UBA（空间天文与物理研究所，阿根廷国家科学研究委员会-布宜诺斯艾利斯大学）
Inferring Stellar Densities with Flexible Models I: The Distribution of RR Lyrae in the Milky Way with $\textit{Gaia}$ DR3
University of Pennsylvania（宾夕法尼亚大学）；Universidad de la República（乌拉圭共和国大学）；Flatiron Institute（平顿研究所）；Max Planck Institute for Astronomy（马克斯·普朗克天文学研究所）；New York University（纽约大学）
The star formation history of CALIFA galaxies: Radial structures
我们研究的径向结构的恒星质量表面密度（$μ$）和恒星星族年龄的函数的总恒星质量和形态的一个样本的107个星系的CALIFA调查。利用化石记录恢复了质量从10 $^9$到10 $^{12}$ M $_\odot$的球状和盘状星系的恒星形成历史。我们推导出半质量半径，我们发现星系的质量平均比光密度小15%。对于盘状星系，HMR/HMR随质量的增加而减小，但在球状星系中几乎是常数。我们发现，星系平均恒星星族年龄，恒星灭绝，和$μ$是很好的代表，他们的值在1。恒星星族年龄的负径向梯度支持由内而外的形成。较大的内部年龄梯度出现在最大质量的盘状星系中，这些星系具有最突出的凸起;较小的年龄梯度出现在类似质量的球状体中。盘状和球状星系显示出负的$μ$梯度，随着恒星质量的增加而变陡。在球状星系中，$μ$饱和在一个临界值，这是独立的星系质量。因此，所有的大质量球状星系在相同的半径（单位为）上都有相似的局部$μ$。超过1光年区域的SFH与其本地的$μ$有很好的相关性，并遵循与星系平均年龄和$μ$相同的关系，这表明本地恒星质量表面密度保持了盘的SFH。然而，球状核的SFH与恒星总质量的关系更为密切，因为尽管所有的球状体星系在$μ$中都具有相似的径向结构，但恒星年龄的径向结构随星系质量的变化而变化。因此，星系质量是一个更基本的性质在球状系统，而当地的恒星质量表面密度是更重要的磁盘。
Globular Clusters in the Time of the JWST. I. Survey Design and First Results on Multiple Populations and Beyond
Università di Padova（帕多瓦大学）；Istituto Nazionale di Astrofisica - Osservatorio Astronomico di Padova（意大利国家天体物理研究所-帕多瓦天文台）；Research School of Astronomy & Astrophysics, Australian National University（澳大利亚国立大学天文学与天体物理学研究学院）；Physics Department, American University of Sharjah（沙迦阿美利加大学物理系）；Space Telescope Science Institute（太空望远镜科学研究所）；Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Roma（意大利国家天体物理研究所-罗马天文台）
The DORCHA suite: nature, nurture, and the phase space distribution of the Milky Way's high redshift progenitors today
Facultad de Físicas, Multidisciplinary Unit for Energy Science, Universidad de Sevilla（塞维利亚大学物理学院能源科学多学科单元）；School of Physics, University of Melbourne（墨尔本大学物理学院）；ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D)（ARC三维全天体物理学卓越中心（ASTRO 3D））；Research School of Astronomy and Astrophysics, Australian National University（澳大利亚国立大学天文与天体物理研究学院）
