Abundances of iron-peak elements in 58 bulge spheroid stars from APOGEE
B. Barbuy, A. C. S. Friaça, H. Ernandes, P. da Silva, S. O. Souza, J. G. Fernández-Trincado, K. Cunha, V. V. Smith, T. Masseron, A. Pérez-Villegas, C. Chiappini… 展开作者
B. Barbuy, A. C. S. Friaça, H. Ernandes, P. da Silva, S. O. Souza, J. G. Fernández-Trincado, K. Cunha, V. V. Smith, T. Masseron, A. Pérez-Villegas, C. Chiappini, A. B. A. Queiroz, B. X. Santiago, T. C. Beers, F. Anders, R. P. Schiavon, M. Valentini, D. Minniti, D. Geisler, D. Souto, V. M. Placco, M. Zoccali, S. Feltzing, M. Schultheis, C. Nitschelm
备注：
12 pages, Astronomy & Astrophysics, accepted on 9/October/2024
Stars presently identified in the bulge spheroid are probably very old, and their abundances can be interpreted as due to the fast chemical enrichment of the early Galactic bulge. The abundances of the iron-peak elements are important tracers of nucleosynthesis processes, in particular oxygen burning, silicon burning, the weak s-process, and alpha-rich freeze-out. Aims. The aim of this work is to derive the abundances of V, Cr, Mn, Co, Ni, and Cu in 58 bulge spheroid stars and to compare them with the results of a previous analysis of data from APOGEE. We selected the best lines for V, Cr, Mn, Co, Ni, and Cu located within the H-band of the spectrum, identifying the most suitable ones for abundance determination, and discarding severe blends. Using the stellar physical parameters available for our sample from the DR17 release of the APOGEE project, we derived the individual abundances through spectrum synthesis. We then complemented these measurements with similar results from different bulge field and globular cluster stars, in order to define the trends of the individual elements and compare with the results of chemical-evolution models. We verify that the H-band has useful lines for the derivation of the elements V, Cr, Mn, Co, Ni, and Cu in moderately metal-poor stars. The resulting abundances indicate that: V, Cr, and Ni vary in lockstep with Fe; Co tends to vary in lockstep with Fe, but could be showing a slight decrease with decreasing metallicity; and Mn and Cu decrease with decreasing metallicity. These behaviours are well reproduced by chemical-evolution models except for Cu, which appears to drop faster than the models predict for moderate metallicities. Finally, abundance indicators combined with kinematical and dynamical criteria appear to show that our 58 sample stars are likely to have originated in situ.
We use the data-driven method, The Cannon, to bring 21,000 stars from the ARGOS bulge survey, including 10,000 red clump stars, onto the parameter and abundance scales of the cross-Galactic survey, APOGEE, obtaining rms precisions of 0.10 dex, 0.07 dex, 74 K, and 0.18 dex for [Fe/H], [Mg/Fe], Teff, and log(g), respectively. The re-calibrated ARGOS survey - which we refer to as the A2A survey - is combined with the APOGEE survey to investigate the abundance structure of the Galactic bulge. We find X-shaped [Fe/H] and [Mg/Fe] distributions in the bulge that are more pinched than the bulge densit…
The central part of the Galaxy host a multitude of stellar populations, including the spheroidal bulge stars, stars moved to the bulge through secular evolution of the bar, inner halo, inner thick disk, inner thin disk, as well as debris from past accretion events. We identified a sample of 58 candidate stars belonging to the stellar population of the spheroidal bulge, and analyse their abundances. The present calculations of Mg, Ca, and Si lines are in agreement with the APOGEE-ASPCAP abundances, whereas abundances of C, N, O, and Ce are re-examined. We find normal $α$-element enhancements in…
We compare abundance ratio trends in a sample of $\sim 11,000$ Milky Way bulge stars ($R_{\rm GC} < 3$ kpc) from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) to those of APOGEE stars in the Galactic disk ($5$ kpc $< R_{\rm GC} < 11$ kpc). We divide each sample into low-Ia (high-[Mg/Fe]) and high-Ia (low-[Mg/Fe]) populations, and in each population we examine the median trends of [X/Mg] vs. [Mg/H] for elements X = Fe, O, Na, Al, Si, P, S, K, Ca, V, Cr, Mn, Co, Ni, Cu, and Ce. To remove small systematic trends of APOGEE abundances with stellar $\log(g)$, we resample the di…
We present elemental abundance analysis of high-resolution spectra for five giant stars, deriving Fe, Mg, Al, C, N, O, Si and Ce abundances, and spatially located within the innermost regions of the bulge globular cluster NGC 6522, based on H-band spectra taken with the multi-object APOGEE-north spectrograph from the SDSS-IV Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey. Of the five cluster candidates, two previously unremarked stars are confirmed to have second-generation (SG) abundance patterns, with the basic pattern of depletion in C and Mg simultaneous with enrich…
The Apache Point Observatory Galactic Evolution Experiment (APOGEE) provides spectroscopic information of regions of the inner Milky Way inaccessible to optical surveys. We present the first large study of the metallicity distribution of the innermost Galactic regions based on homogeneous measurements from the SDSS Data Release 12 for 7545 red giant stars within 4.5 kpc of the Galactic center, with the goal to shed light on the structure and origin of the Galactic bulge. Stellar metallicities are found, through multiple-Gaussian decompositions, to be distributed in several components indicativ…
Two Groups of Red Giants with Distinct Chemical Abundances in the Bulge Globular Cluster NGC 6553 Through the Eyes of APOGEE
在球状星团中发现的多星族是研究这些恒星系统形成和演化的重要窗口。银河系隆起中富含金属的GC是这张照片中不可或缺的一部分，但该地区的高光学消光阻碍了广泛的研究。在这项工作中，我们使用APOGEE的高分辨率近红外（NIR）光谱数据来研究NGC 6553的化学丰度，这是最富金属的凸起GC之一。我们确定了10个红巨星集群成员使用他们的位置，径向速度，铁丰度，和近红外测光。我们的样本星显示出平均径向速度为$-0.14\pm5.47$ km s $^{-1}$，平均[Fe/H]为$-0.15\pm 0.05$。我们清楚地分开两个人口的恒星在C和N在这个GC的第一次。NGC 6553是迄今为止发现多恒星星族现象的最富金属的GC。大量的化学变化也被发现在Na，O和Al。然而，这两个人口显示出相似的Si，Ca和铁峰元素丰度。因此，我们推断CNO、NeNa和MgAl循环已经被激活，但MgAl循环太弱而不能显示其对Mg的影响。Ia型和II型超新星似乎没有严重污染第二代恒星。与其他GC研究相比，NGC 6553显示出与其他相对富金属GC相似的化学变化。我们也面对目前的GC形成理论与我们的研究结果，并提出可能的途径，改进模型。
Chemical radial gradients for the bulge-bar stellar populations from the APOGEE survey
Observatório Nacional/MCTI（巴西国家天文台）；Steward Observatory, University of Arizona（亚利桑那大学斯图尔德天文台）；NOIRLab（美国国家光学-红外天文研究实验室）；Departamento de Física, Universidade Federal de Sergipe（塞尔希培联邦大学物理系）；Universidad Católica del Norte, Núcleo UCN en Arqueología Galáctica - Inst. de Astronomía（北天主教大学UCN银河考古核心-天文研究所）；Instituto de Astrofísica de Canarias (IAC)（加那利群岛天体物理研究所）；Universidad de La Laguna (ULL), Departamento de Astrofísica（拉帕尔马大学天体物理学系）；Leibniz-Institut für Astrophysik Potsdam (AIP)（波茨坦阿基米德天体物理研究所）
The latest edition of the APOGEE-2/DR14 survey catalogue and the first \texttt{Payne} data release of APOGEE abundance determinations by Ting et al. are examined. We identify 31 previously unremarked metal-poor giant stars with anomalously high levels of nitrogen in the chemical space defined by [Fe/H] and [N/Fe]. The APOGEE chemical abundance patterns of such objects revealed that these are chemically distinct from the Milky Way (MW) in most chemical elements. We have found all these objects have a [N/Fe]$>+0.5$, and are thus identified here as nitrogen-rich stars. An orbital analysis of thes…
The age and chemical characteristics of the Galactic bulge link to the formation and evolutionary history of the Galaxy. Data-driven methods and large surveys enable stellar ages and precision chemical abundances to be determined for vast regions of the Milky Way, including the bulge. Here, we use the data-driven approach of The Cannon, to infer the ages and abundances for 125,367 stars in the Milky Way, using spectra from Apache Point Observatory Galaxy Evolution Experiment (APOGEE) DR14. We examine the ages and metallicities of 1654 bulge stars within $R_{\text{GAL}}<3.5$ kpc. We focus on fi…
The central kiloparsecs of the Milky Way are known to host an old, spheroidal stellar population, whose spatial and kinematical properties set it apart from the boxy/peanut structure that constitutes most of the central stellar mass. The nature of this spheroidal population, whether a small classical bulge, the innermost stellar halo or a population of disk stars with large initial velocity dispersion, remains unclear. This structure is also a promising candidate to host some of the oldest stars in the Galaxy. Here we address the topic of the inner stellar spheroid age, using spectroscopic and…
