More than a decade has passed since the definition of Globular Cluster (GC) changed, and now we know that they host Multiple Populations (MPs). But few GCs do not share that behaviour and Ruprecht 106 is one of these clusters. We analyzed thirteen member red giant branch stars using spectra in the wavelength range 6120-6405 Angstroms obtained through the GIRAFFE Spectrograph, mounted at UT2 telescope at Paranal, as well as the whole cluster using C, V, R and I photometry obtained through the Swope telescope at Las Campanas. Atmospheric parameters were determined from the photometry to determine Fe and Na abundances. A photometric analysis searching for MPs was also carried out. Both analyses confirm that Ruprecht 106 is indeed one on the few GCs to host Simple Stellar Population, in agreement with previous studies. Finally, a dynamical study concerning its orbits was carried out to analyze the possible extra galactic origin of the Cluster. The orbital integration indicates that this GC belongs to the inner halo, while an Energy plane shows that it cannot be accurately associated with any known extragalactic progenitor.
In the framework of the Stellar Population Astrophysics (SPA) project, we present new observations and spectral analysis of four sparsely studied open clusters, namely Collinder 350, Gulliver 51, NGC 7044, and Ruprecht 171. We exploit the HARPS-N spectrograph at the TNG telescope to acquire high-resolution optical spectra for 15 member stars of four clusters. We derive stellar parameters using both the EW analysis and the spectral fitting technique. We compute elemental abundances for light, a-, iron-peak, and n-capture elements using the EW measurement approach. We investigate the origin of t…
Recent work has shown that the properties of multiple populations within massive stellar clusters (i.e., in the extent of their abundance variations as well as the fraction of stars that show the anomalous chemistry) depend on the mass as well as the age of the host cluster. Such correlations are largely unexpected in current models for the formation of multiple populations and hence provide essential insight into their origin. Here we extend or previous study into the presence or absence of multiple populations using integrated light spectroscopy of the $\sim600$~Myr, massive ($\sim10^7 - 10^…
Searching for chemical inhomogeneities in Open Clusters: Analysis of the CN and CH Molecular Band Strengths in NGC 2158, NGC 2420, NGC 2682, NGC 7789 and Berkeley 29
A search for white dwarfs in the Galactic plane: the field and the open cluster population
我们研究了在银河系低纬度地区系统搜索白矮星的前景，使用VLT巡天望远镜（VST）H $α$银河系平面和凸起光度测量（VPHAS+）。我们沿着已知的疏散星团的视线瞄准了17颗白矮星候选者，旨在确定潜在的星团成员。我们确认了所有17个白矮星候选者的蓝色/光学光谱，我们建议其中五个可能是集群成员。我们估计了候选星系团成员的祖先年龄和质量，并将我们的发现与其他星系团白矮星的发现进行了比较。NGC 3532中的白矮星是已知质量最大的星团成员（1.13 M PDMATHAMN），可能具有氧氖核心，我们估计它的$8.8_{-4.3}^{+1.2}$ M $_{\odot}$祖先，接近白矮星和中子星祖先之间的质量分界线。Ruprecht 131的星团成员是一颗磁性白矮星，其前身质量超过2-3 M $_{\odot}$。我们强调，更广泛的搜索，并改进集群距离和年龄来自欧空局盖亚任务的数据，将促进对低至中等质量恒星的质量损失过程的理解。
It is uncertain whether or not low-mass Population III stars ever existed. While limits on the number density of Population III stars with $M_{\ast} \approx 0.8~M_{\odot}$ have been derived using Sloan Digital Sky Survey (SDSS) data, little is known about the occurrence of Population III stars at lower masses. In the absence of reliable parallaxes, the spectra of metal-poor main sequence (MPMS) stars with $M_{\ast} \lesssim 0.8~M_{\odot}$ can easily be confused with cool white dwarfs. To resolve this ambiguity, we present a classifier that differentiates between MPMS stars and white dwarfs bas…
Multiple stellar populations (MPs) in most star clusters older than 2 Gyr, as seen by lots of spectroscopic and photometric studies, have led to a significant challenge to the traditional view of star formation. In this field, space-based instruments, in particular the Hubble Space Telescope (HST), have made a breakthrough as they significantly improved the efficiency of detecting MPs in crowding stellar fields by images. The China Space Station Telescope (CSST) and the HST are sensitive to a similar wavelength interval, but it covers a field of view which is about 5-8 times wider than that of…
The conventional picture of coeval, chemically homogeneous, populous star clusters -- known as `simple stellar populations' (SSPs) -- is a view of the past. Photometric and spectroscopic studies reveal that almost all ancient globular clusters in the Milky Way and our neighbouring galaxies exhibit star-to-star light-element abundance variations, typically known as 'multiple populations' (MPs). Here, we analyse photometric $\it Hubble$ $\it Space$ $\it Telescope$ observations of three young ($<$2 Gyr-old) Large and Small Magellanic Cloud clusters, NGC 411, NGC 1718 and NGC 2213. We measure the …
CHORD HI-Galaxy Survey Forecasts: Searching for nearby dark galaxies and high redshift giants
Queen’s University（女王大学）；Perimeter Institute for Theoretical Physics（理论物理前沿研究所）；University of Waterloo（滑铁卢大学）；McGill University（麦吉尔大学）；Trottier Space Institute（特罗蒂尔太空研究所）；Arizona State University（亚利桑那州立大学）；University of British Columbia（不列颠哥伦比亚大学）；National Research Council（国家研究委员会）
Context: We present COSTA (COld STream finder Algorithm), a novel algorithm to search for cold kinematical substructures in the phase space of planetary nebulae (PNe) and globular clusters (GCs) in the halo of massive galaxies and intracluster regions. Aims: COSTA aims at detecting small sized, low velocity dispersion streams, as the ones produced in recent interactions of dwarf galaxies with the halo of more massive galaxies, including the ones sitting in the central region of rich galaxy clusters. Methods: COSTA is based on a deep friend-of-friend procedure that isolates groups of N particle…
Searching for GC-like abundance patterns in young massive clusters
过去十年的研究表明，几乎所有的球状星团（GC）都拥有多个恒星种群（MP），这些恒星在轻元素中具有独特的化学模式。到目前为止，在低质量的疏散星团（$< \sim 10^4$ M $_{\odot}$）和本星系群的中等年龄（1-2 Gyr）的大质量星团（$> 10^5$ M $_{\odot}$）中，都没有发现这种MP的证据。年轻的大质量星团（YMC）的质量和密度与早期宇宙中年轻GC的预期相似，它们的近红外光谱（NIR）主要由红超巨星（RSG）的光主导。这些恒星的光谱可以用来确定星团的丰度，即使单个恒星不能在空间上相互分辨。本文对YMC NGC 1705：1和具有相似金属丰度的小麦哲伦云RSG的Al谱线进行了差异分析。我们排除了在高置信度极端[Al/Fe]增强类似的GC中观察到的NGC 2808或NGC 6752。然而，不能排除较小的变化。
Context: Debris discs orbiting young stars are key to understand dust evolution and the planetary formation process. We take advantage of a recent membership analysis of the 30 Myr nearby open cluster IC 4665 based on the Gaia and DANCe surveys to revisit the disc population of this cluster. Aims: We aim to study the disc population of IC 4665 using Spitzer (MIPS and IRAC) and WISE photometry. Methods: We use several colour-colour diagrams with empirical photospheric sequences to detect the sources with an infrared excess. Independently, we also fit the spectral energy distribution (SED) of ou…
Searching for White Dwarf Candidates Formed Through Binary evolution in Star Clusters
School of Physics and Astronomy, Sun Yat-sen University（中山大学物理学院）；CSST Science Center for the Guangdong–Hong Kong–Macau Greater Bay Area（粤港澳大湾区宇宙线科学中心）；Department of Physics and Astronomy, University of British Columbia（不列颠哥伦比亚大学物理与天文学系）；Department of Physics, Xi’an Jiaotong–Liverpool University（西交利物浦大学物理系）；Shanghai Key Laboratory for Astrophysics, Shanghai Normal University（上海师范大学天体物理上海市重点实验室）；National Astronomical Observatories（国家天文台）
