Chemical abundance gradients from open clusters in the Milky Way disk: results from the APOGEE survey
Katia Cunha, Peter M. Frinchaboy, Diogo Souto, Benjamin Thompson, Gail Zasowski, Carlos Allende Prieto, Ricardo Carrera, Cristina Chiappini, John Donor, Anibal … 展开作者
Katia Cunha, Peter M. Frinchaboy, Diogo Souto, Benjamin Thompson, Gail Zasowski, Carlos Allende Prieto, Ricardo Carrera, Cristina Chiappini, John Donor, Anibal Garcia-Hernandez, Ana Elia Garcia Perez, Michael R. Hayden, Jon Holtzman, Kelly M. Jackson, Jennifer A. Johnson, Steven R. Majewski, Szabolcs Meszaros, Brianne Meyer, David L. Nidever, Julia O'Connell, Ricardo P. Schiavon, Mathias Schultheis, Matthew Shetrone, Audrey Simmons, Verne V. Smith, Olga Zamora
备注：
4 pages, 3 figures, To appear in Astronomische Nachrichten, special issue "Reconstruction the Milky Way's History: Spectroscopic surveys, Asteroseismology and Chemo-dynamical models", Guest Editors C. Chiappini, J. Montalbán, and M. Steffen, AN 2016 (in press)"
Metallicity gradients provide strong constraints for understanding the chemical evolution of the Galaxy. We report on radial abundance gradients of Fe, Ni, Ca, Si, and Mg obtained from a sample of 304 red-giant members of 29 disk open clusters, mostly concentrated at galactocentric distances between ~8 - 15 kpc, but including two open clusters in the outer disk. The observations are from the APOGEE survey. The chemical abundances were derived automatically by the ASPCAP pipeline and these are part of the SDSS III Data Release 12. The gradients, obtained from least squares fits to the data, are relatively flat, with slopes ranging from -0.026 to -0.033 dex/kpc for the alpha-elements [O/H], [Ca/H], [Si/H] and [Mg/H] and -0.035 dex/kpc and -0.040 dex/kpc for [Fe/H] and [Ni/H], respectively. Our results are not at odds with the possibility that metallicity ([Fe/H]) gradients are steeper in the inner disk (R_GC ~7 - 12 kpc) and flatter towards the outer disk. The open cluster sample studied spans a significant range in age. When breaking the sample into age bins, there is some indication that the younger open cluster population in our sample (log age < 8.7) has a flatter metallicity gradient when compared with the gradients obtained from older open clusters.
APOGEE is a high-resolution (R sim 22,000), near-infrared, multi-epoch, spectroscopic survey of the Milky Way. The second generation of the APOGEE project, APOGEE-2, includes an expansion of the survey to the Southern Hemisphere called APOGEE-2S. This expansion enabled APOGEE to perform a fully panoramic mapping of all the main regions of the Milky Way; in particular, by operating in the H-band, APOGEE is uniquely able to probe the dust-hidden inner regions of the Milky Way that are best accessed from the Southern Hemisphere. In this paper we present the targeting strategy of APOGEE-2S, with s…
The disc origin of the Milky Way bulge: Dissecting the chemo-morphological relations using N-body simulations and APOGEE
关于银河系（MW）核球中贫金属恒星星族的起源有一个长期的争论，两种主要的假设是这些恒星族要么是i）经典贫金属椭球体的一部分，要么是ii）与太阳附近化学定义的厚盘相同的恒星族。在这里，我们测试后一种情况下是否可以重现所观察到的MW凸起的化学性质。要做到这一点，我们比较了一个复合（薄+厚）恒星盘的N体模拟-它长期演变形成一个酒吧和一个方形/花生（b/p）凸起-从APOGEE DR 13的数据。这个模型中厚盘是大质量的，并且集中在中心，可以再现核球中富金属和贫金属恒星星族的形态，以及从APOGEE数据获得的平均金属丰度和[ $α$ /Fe]图。它还再现了隆凸金属丰度分布函数（BMT）在经度和纬度上的趋势。此外，我们表明，该模型预测小，但可测量的方位角金属丰度的变化，由于在酒吧的薄，厚光盘的差分映射在内部光盘。因此，我们看到，MW核球中恒星星族的化学形态关系，可以通过将内部MW的薄盘和厚盘映射到b/p中而自然地再现。
We use accurate estimates of aluminium abundance provided as part of the APOGEE Data Release 17 and Gaia Early Data Release 3 astrometry to select a highly pure sample of stars with metallicity $-1.5\lesssim {\rm [Fe/H]}\lesssim 0.5$ born in-situ in the Milky Way proper. We show that the low-metallicity ([Fe/H]$\lesssim -1.3$) in-situ component that we dub Aurora is kinematically hot with an approximately isotropic velocity ellipsoid and a modest net rotation. Aurora stars exhibit large scatter in metallicity and in a number of element abundance ratios. The median tangential velocity of the in…
APOGEE and GALAH are two high resolution multi-object spectroscopic surveys that provide fundamental stellar parameters and multiple elemental abundance estimates for about half a million stars in the Milky Way. Both surveys observe in different wavelength regimes and use different data reduction pipelines leading to significant offsets and trends in stellar parameters and abundances for the common stars observed in both surveys. Such systematic differences/offsets in stellar parameters and abundances make it difficult to effectively utilise them to investigate Galactic abundance trends in spi…
The Apache Point Observatory extra-Galactic Evolution Experiment (APOeGEE): Chemical Abundance Trends for Seven Dwarf Spheroidal Galaxies in the APOGEE Survey
We use data from the 17th data release of the Apache Point Observatory Galactic Evolution Experiment (APOGEE 2) to contrast the chemical composition of the recently discovered Gaia Enceladus/Sausage system (GE/S) to those of ten Milky Way (MW) dwarf satellite galaxies: LMC, SMC, Boötes I, Carina, Draco, Fornax, Sagittarius, Sculptor, Sextans and Ursa Minor. Our main focus is on the distributions of the stellar populations of those systems in the [Mg/Fe]-[Fe/H] and [Mg/Mn]-[Al/Fe] planes, which are commonly employed in the literature for chemical diagnosis and where dwarf galaxies can be distin…
We construct a dynamical model of the Milky Way disk from a data set, which combines Gaia EDR3 and APOGEE data throughout Galactocentric radii between $5.0\leq R\leq19.5$ kpc. We make use of the spherically-aligned Jeans Anisotropic Method to model the stellar velocities and their velocity dispersions. Building upon our previous work, our model now is fitted to kinematic maps that have been extended to larger Galactocentric radii due to the expansion of our data set, probing the outer regions of the Galactic disk. Our best-fitting dynamical model suggests a logarithmic density slope of $α_{\rm…
(ABRIDGED) We use the 17th data release of the second phase of the Apache Point Observatory Galactic Evolution Experiment (APOGEE-2) to provide a homogenous census of N-rich red giant stars across the Milky Way (MW). We report a total of 149 newly identified N-rich field giants toward the bulge, metal-poor disk, and halo of our Galaxy. They exhibit significant enrichment in their nitrogen abundance ratios ([N/Fe] $\gtrsim+0.5$), along with simultaneous depletions in their [C/Fe] abundance ratios ([C/Fe] $< +0.15$), and they cover a wide range of metallicities ($-1.8 < $ [Fe/H] $ <-0.7$). The f…
Rediscovering the Milky Way with an orbit superposition approach and APOGEE data V. The disc growth and history of star formation
Leibniz-Institut für Astrophysik Potsdam (AIP)（波茨坦阿基米德天体物理研究所）；Department of Astrophysics, University of Vienna（维也纳大学天体物理系）；BIFOLD, Berlin Institute for the Foundations of Learning and Data（柏林学习与数据基础研究所）；LIRA, Observatoire de Paris, Université PSL, Sorbonne Université, Université Paris Cité, CY Cergy Paris Université, CNRS（巴黎天文台LIRA实验室，巴黎文理研究大学，索邦大学，巴黎西岱大学，CY塞尔吉巴黎大学，法国国家科学研究中心）；Universität Potsdam, Institut für Physik und Astronomie（波茨坦大学物理与天文学研究所）；Friedrich-Schiller Uni（弗里德里希·席勒大学）
The SDSS-IV Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey has obtained high-resolution spectra for thousands of red giant stars distributed among the massive satellite galaxies of the Milky Way (MW): the Large and Small Magellanic Clouds (LMC/SMC), the Sagittarius Dwarf (Sgr), Fornax (Fnx), and the now fully disrupted \emph{Gaia} Sausage/Enceladus (GSE) system. We present and analyze the APOGEE chemical abundance patterns of each galaxy to draw robust conclusions about their star formation histories, by quantifying the relative abundance trends of multiple elements (C,…
Galactic haloes in a $Λ$-CDM universe are predicted to host today a swarm of debris resulting from cannibalised dwarf galaxies. The chemo-dynamical information recorded in their stellar populations helps elucidate their nature, constraining the assembly history of the Galaxy. Using data from APOGEE and \textit{Gaia}, we examine the chemical properties of various halo substructures, considering elements that sample various nucleosynthetic pathways. The systems studied are Heracles, \textit{Gaia}-Enceladus/Sausage (GES), the Helmi stream, Sequoia, Thamnos, Aleph, LMS-1, Arjuna, I'itoi, Nyx, Icar…
We apply a novel statistical analysis to measurements of 16 elemental abundances in 34,410 Milky Way disk stars from the final data release (DR17) of APOGEE-2. Building on recent work, we fit median abundance ratio trends [X/Mg] vs. [Mg/H] with a 2-process model, which decomposes abundance patterns into a "prompt" component tracing core collapse supernovae and a "delayed" component tracing Type Ia supernovae. For each sample star, we fit the amplitudes of these two components, then compute the residuals Δ[X/H] from this two-parameter fit. The rms residuals range from ~0.01-0.03 dex for the mos…
The central (`bulge') region of the Milky Way is teeming with a significant fraction of mildly metal-deficient stars with atmospheres that are strongly enriched in cyanogen ($^{12}$C$^{14}$N). Some of these objects, which are also known as nitrogen-enhanced stars, are hypothesised to be relics of the ancient assembly history of the Milky Way. Although the chemical similarity of nitrogen-enhanced stars to the unique chemical patterns observed in globular clusters has been observed, a direct connection between field stars and globular clusters has not yet been proven. In this work, we report on …
The metal-poor tail of the APOGEE survey II. Spectral analysis of Mg and Si in very metal-poor APOGEE spectra
Kapteyn Astronomical Institute, University of Groningen（格罗宁根大学卡佩因天文研究所）；University of Hertfordshire（赫特福德大学）；Institute of Astronomy, University of Cambridge（剑桥大学天文学研究所）；Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange（蔚蓝海岸大学、蔚蓝海岸天文台、法国国家科学研究中心、拉格朗日实验室）；École Polytechnique Fédérale de Lausanne (EPFL)（洛桑联邦理工学院）；Université de Strasbourg, CNRS, Observatoire astronomique de Strasbourg（斯特拉斯堡大学、法国国家科学研究中心、斯特拉斯堡天文台）；Max-Planck-Institut für Astronomie（马克斯·普朗克天文学研究所）；University of Victoria（维多利亚大学）
The formation of the Galactic disc is an enthusiastically debated issue. Numerous studies and models seek to identify the dominant physical process(es) that shaped its observed properties. Taking advantage of the improved coverage of the inner Milky Way provided by the SDSS DR16 APOGEE catalogue and of the ages published in the APOGEE-AstroNN Value Added Catalogue (VAC), we examine the radial evolution of the chemical and age properties of the Galactic stellar disc, with the aim to better constrain its formation. Using a sample of 199,307 giant stars with precise APOGEE abundances and APOGEE-a…
We present stellar age distributions of the Milky Way (MW) bulge region using ages for $\sim$6,000 high-luminosity ($\log(g) < 2.0$), metal-rich ($\rm [Fe/H] \ge -0.5$) bulge stars observed by the Apache Point Observatory Galactic Evolution Experiment (APOGEE). Ages are derived using {\it The Cannon} label-transfer method, trained on a sample of nearby luminous giants with precise parallaxes for which we obtain ages using a Bayesian isochrone-matching technique. We find that the metal-rich bulge is predominantly composed of old stars ($>$8 Gyr). We find evidence that the planar region of the b…
We present the kinematic and chemical profiles of red giant stars observed by the APOGEE-2 survey in the direction of the Jhelum stellar stream, a Milky Way substructure located in the inner halo of the Milky Way at a distance from the Sun of $\approx$ 13 kpc. From the six APOGEE-2 Jhelum pointings, we isolate stars with log($g$) $<$ 3.5, leaving a sample of 289 red giant stars. From this sample of APOGEE giants, we identified seven stars that are consistent with the astrometric signal from $Gaia$ DR2 for this stream. Of these seven, one falls onto the RGB along the same sequence as the Jhelum…
We report evidence from APOGEE for the presence of a new metal-poor stellar structure located within $\sim$4~kpc of the Galactic centre. Characterised by a chemical composition resembling those of low mass satellites of the Milky Way, this new inner Galaxy structure (IGS) seems to be chemically and dynamically detached from more metal-rich populations in the inner Galaxy. We conjecture that this structure is associated with an accretion event that likely occurred in the early life of the Milky Way. Comparing the mean elemental abundances of this structure with predictions from cosmological num…
