scholarly journals The GALAH survey: tracing the Galactic disk with open clusters

2021 ◽  
Author(s):  
Lorenzo Spina ◽  
Yuan-Sen Ting ◽  
Gayandhi M De Silva ◽  
Neige Frankel ◽  
Sanjib Sharma ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Spectroscopic Data ◽  
Galactic Disk ◽  
Chemical Elements ◽  
Selection Effect ◽  
Open Clusters ◽  
High Quality ◽  
Radial Migration ◽  
History Of ◽  
Chemical Distribution

Abstract Open clusters are unique tracers of the history of our own Galaxy’s disk. According to our membership analysis based on Gaia astrometry, out of the 226 potential clusters falling in the footprint of GALAH or APOGEE, we find that 205 have secure members that were observed by at least one of the survey. Furthermore, members of 134 clusters have high-quality spectroscopic data that we use to determine their chemical composition. We leverage this information to study the chemical distribution throughout the Galactic disk of 21 elements, from C to Eu. The radial metallicity gradient obtained from our analysis is −0.076 ± 0.009 dex kpc−1, which is in agreement with previous works based on smaller samples. Furthermore, the gradient in the [Fe/H] - guiding radius (rguid) plane is −0.073 ± 0.008 dex kpc−1. We show consistently that open clusters trace the distribution of chemical elements throughout the Galactic disk differently than field stars. In particular, at given radius, open clusters show an age-metallicity relation that has less scatter than field stars. As such scatter is often interpreted as an effect of radial migration, we suggest that these differences are due to the physical selection effect imposed by our Galaxy: clusters that would have migrated significantly also had higher chances to get destroyed. Finally, our results reveal trends in the [X/Fe]-rguid-age space, which are important to understand production rates of different elements as a function of space and time.

scholarly journals A Gaia DR2 view of the open cluster population in the Milky Way

2018 ◽  
Vol 618 ◽  
pp. A93 ◽  
Author(s):  
T. Cantat-Gaudin ◽  
C. Jordi ◽  
A. Vallenari ◽  
A. Bragaglia ◽  
L. Balaguer-Núñez ◽  
...  
Keyword(s):  
Stellar Evolution ◽  
Milky Way ◽  
Galactic Plane ◽  
Galactic Disk ◽  
Open Cluster ◽  
Open Clusters ◽  
Number Of Clusters ◽  
History Of ◽  
Gaia Dr2

Context. Open clusters are convenient probes of the structure and history of the Galactic disk. They are also fundamental to stellar evolution studies. The second Gaia data release contains precise astrometry at the submilliarcsecond level and homogeneous photometry at the mmag level, that can be used to characterise a large number of clusters over the entire sky. Aims. In this study we aim to establish a list of members and derive mean parameters, in particular distances, for as many clusters as possible, making use of Gaia data alone. Methods. We compiled a list of thousands of known or putative clusters from the literature. We then applied an unsupervised membership assignment code, UPMASK, to the Gaia DR2 data contained within the fields of those clusters. Results. We obtained a list of members and cluster parameters for 1229 clusters. As expected, the youngest clusters are seen to be tightly distributed near the Galactic plane and to trace the spiral arms of the Milky Way, while older objects are more uniformly distributed, deviate further from the plane, and tend to be located at larger Galactocentric distances. Thanks to the quality of Gaia DR2 astrometry, the fully homogeneous parameters derived in this study are the most precise to date. Furthermore, we report on the serendipitous discovery of 60 new open clusters in the fields analysed during this study.

scholarly journals Galaxy simulations in the Gaia era

2017 ◽  
Vol 12 (S330) ◽  
pp. 127-135
Author(s):  
Ivan Minchev
Keyword(s):  
Chemical Composition ◽  
Numerical Simulations ◽  
Spectroscopic Data ◽  
Milky Way ◽  
Disk Galaxies ◽  
Physical Processes ◽  
Radial Migration ◽  
Cosmological Context ◽  
Enormous Amount ◽  
Formation And Evolution

AbstractWe live in an age where an enormous amount of astrometric, photometric, asteroseismic, and spectroscopic data of Milky Way stars are being acquired, many orders of magnitude larger than about a decade ago. Thanks to the Gaia astrometric mission and followup ground-based spectroscopic surveys in the next 5-10 years about 10-20 Million stars will have accurate 6D kinematics and chemical composition measurements. KEPLER-2, PLATO, and TESS will provide asteroseismic ages for a good fraction of those. In this article we outline some outstanding problems concerning the formation and evolution of the Milky Way and argue that, due to the complexity of physical processes involved in the formation of disk galaxies, numerical simulations in the cosmological context are needed for the interpretation of Milky Way observations. We also discuss in some detail the formation of the Milky Way thick disk, chemodynamical models, and the effects of radial migration.

Influence of Chemical Composition of Tough-to-Machine Materials on Grinding Technologies

2017 ◽  
Vol 265 ◽  
pp. 793-799
Author(s):  
T.N. Ivanova
Keyword(s):  
Chemical Composition ◽  
Chemical Elements ◽  
Grinding Wheels ◽  
Surface Layers ◽  
High Quality ◽  
Synthetic Diamonds ◽  
Machine Steel ◽  
Steel Grades ◽  
Quality Surface ◽  
High Quality Surface

The main purpose of processing of tough-to-machine materials is improving of cutting process of steels with different physicochemical properties and alloying by means of various chemical elements in combination with heat treatment. Producing of high quality surface layers depends on properties of material used to make details, that is why reasons of tough machining were identified: influence of chemical composition and resulting structure. The studies of grinding of tough-to-machine materials were undertaken by means of grinding wheels made from synthetic diamonds as they are most resistant and highly-productive. Based on the studies recommendations for using of characteristics of grinding wheels and tough-to machine steel grades.

Using open clusters as tracers of the galactic disk history

2017 ◽  
Vol 13 (S334) ◽  
pp. 312-313
Author(s):  
Orlando J. Katime Santrich ◽  
Silvia Rossi ◽  
Yuri Abuchaim ◽  
Geraldo Gonçalves
Keyword(s):  
Chemical Composition ◽  
High Resolution ◽  
Spectroscopic Analysis ◽  
Galactic Disk ◽  
Dynamical Behavior ◽  
Open Clusters ◽  
Atmospheric Parameters ◽  
Giant Stars ◽  
Stellar Formation ◽  
Formation And Evolution

AbstractOpen clusters are important objects to study the galactic structure and its dynamical behavior as well as the stellar formation and evolution. We carried out a spectroscopic analysis to derive atmospheric parameters and chemical composition for 52 giant stars within 9 galactic open clusters. We have used the high-resolution spectra from FEROS, HARPS and UVES in the ESO archive. The methodology used is based on LTE-hypothesis. Abundances of C, N, O, Na, Mg, Al, Si, Ca, Ti, Cr, Ni, YII, LaII, CeII, and NdII were calculated. Although most of these clusters present spectroscopic analysis in the literature, some CNO and s-process abundances were not previously estimated or were calculated with high uncertainties. Several lines of such elements were identified and used to calculate new abundances and improve some previous one.

scholarly journals A phylogenetic approach to chemical tagging

2018 ◽  
Vol 618 ◽  
pp. A65 ◽  
Author(s):  
Sergi Blanco-Cuaresma ◽  
Didier Fraix-Burnet
Keyword(s):  
Chemical Elements ◽  
Phylogenetic Analyses ◽  
Open Cluster ◽  
Open Clusters ◽  
Evolutionary Stage ◽  
The Sun ◽  
Chemical Abundances ◽  
Chemical Tagging ◽  
The Galaxy ◽  
History Of

Context. The chemical tagging technique is a promising approach to reconstructing the history of the Galaxy by only using stellar chemical abundances. Multiple studies have undertaken this analysis and they have raised several challenges. Aims. Using a sample of open cluster stars, we wish to address two issues: minimize chemical abundance differences whose origin is linked to the evolutionary stage of the stars and not their original composition and evaluate a phylogenetic approach to group stars based on their chemical composition. Methods. We derived differential chemical abundances for 207 stars, belonging to 34 open clusters, using the Sun as reference star (classical approach) and a dwarf plus a giant star from the open cluster M 67 as reference (new approach). These abundances were then used to perform two phylogenetic analyses: cladistics (maximum parsimony) and neighbor joining, together with a partitioning unsupervised classification analysis with k-means. The resulting groupings were finally confronted to the true open cluster memberships of the stars. Results. We successfully reconstruct most of the original open clusters when carefully selecting a subset of the abundances derived differentially with respect to M 67. We find a set of eight chemical elements that yield the best result and discuss the possible reasons for these elements to be good tracers of the history of the Galaxy. Conclusions. Our study shows that unraveling the history of the Galaxy by only using stellar chemical abundances is greatly improved provided that i) we perform a differential spectroscopic analysis with respect to an open cluster instead of the Sun, ii) select the chemical elements that are good tracers of the history of the Galaxy, and iii) use tools that are adapted to detect evolutionary tracks such as phylogenetic approaches.

scholarly journals Abundances of seven red giants in the open cluster NGC 3114

2009 ◽  
Vol 5 (S266) ◽  
pp. 495-498
Author(s):  
C. B. Pereira ◽  
C. Quireza
Keyword(s):  
Chemical Composition ◽  
Chemical Analysis ◽  
Galactic Disk ◽  
Open Cluster ◽  
Open Clusters ◽  
Red Giants ◽  
The Sun ◽  
Atmospheric Parameters ◽  
Red Giant ◽  
Good Agreement

AbstractWe present a chemical analysis of seven red giants in the open cluster NGC 3114. Our main goal is to investigate the chemical composition of this cluster, which is not yet available in the literature. We employed the FEROS spectrograph on the ESO 2.2m telescope. Atmospheric parameters and metallicity were derived from the measured equivalent widths of several iron lines using the spectral code moog and Kurucz model atmospheres. We obtained the abundances of O, Al, Ca, Mg, Si, Ti, Ni, Cr, Sc, Y, Zr, La, Ce and Nd by measuring the equivalent widths of the absorption lines of these elements. A mean metallicity of [Fe/H] = 0.05 ± 0.13 relative to the Sun was determined from the data of the red-giant members. This result is in good agreement with the Galactic-disk radial distribution of iron traced by open clusters. We did not find any intrinsic star-to-star scatter in the [element/Fe] ratios for the stars in this cluster. We compare our results with investigations of other open clusters. An age of 8.2 Gyr is derived from isochrone fits.

scholarly journals Devising criteria for the authenticity of historical cold weapons based on X-ray fluorescence analysis of their surface

2021 ◽  
Vol 6 (12 (114)) ◽  
Author(s):  
Nina Merezhko ◽  
Yuliia Vovk ◽  
Volodymyr Indutnyi ◽  
Kateryna Pirkovich ◽  
Valentyna Davydiuk ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Chemical Elements ◽  
Fluorescence Analysis ◽  
Pure Material ◽  
X Ray ◽  
Subsequent Investigation ◽  
Study Results ◽  
Chronological Period ◽  
Historical Objects ◽  
History Of

This paper reports the results of studying the chemical composition of the surface of 4 objects of cold weapons of the 19th and early 20th centuries, made of iron – bayonet knives and sabers. This makes it possible to establish the signs of authenticity of cold weapon samples made of iron in that chronological period. An authentic procedure has been proposed for examining the chemical composition of the surface of historical objects of cold weapons by rubbing the samples with cotton wool swabs and their subsequent investigation. This makes it possible to explore objects of cold weapons, whose size is large, as well as simplify the very procedure for studying objects of historical and cultural value. Using the X-ray fluorescent chemical analyzer Expert Mobile, chemical elements were found at the surface of samples of cold weapons made of iron. The presence of such elements is the result of the process of re-crystallization and self-purification of metal during a long history of its life. Elements found in almost every rubbing sample were identified: calcium, ferrum, zinc, cuprum, and chlorine. The studies of cold weapons samples testify to the heterogeneity of the composition of patina formations on their surface, which confirms the authenticity of ancient objects. In addition, the studies have shown a difference in the chemical composition of surface layers of different parts of individual samples of antique cold weapons, which may indicate different times or different technology for their manufacture. The fluorescence spectra of the obtained rubbing of individual samples of cold weapons were compared with "pure" material, which made it possible to identify elements removed from the surface of objects. The study results are important indicators to confirm the authenticity of cultural monuments and the technology of their manufacture in the past.

scholarly journals Chemical Composition of the RS CNn-Type Star 33 Piscium

2011 ◽  
Vol 20 (1) ◽  
Author(s):  
G. Barisevišius ◽  
G. Tautvaišienė ◽  
S. Berdyugina ◽  
Y. Chorniy ◽  
I. Ilyin
Keyword(s):  
Chemical Composition ◽  
Chemical Elements ◽  
Type Star

AbstractAbundances of 22 chemical elements, including the key elements and isotopes such as

scholarly journals Contribution of White Dwarfs to Cluster Masses

1998 ◽  
Vol 11 (1) ◽  
pp. 430-432
Author(s):  
Ted Von Hippel
Keyword(s):  
Stellar Evolution ◽  
Mass Fraction ◽  
Globular Clusters ◽  
White Dwarfs ◽  
Literature Search ◽  
Galactic Disk ◽  
Dynamical Evolution ◽  
Open Clusters ◽  
Solar Neighborhood ◽  
Current Evidence

The study of cluster white dwarfs (WDs) has been invigorated recently bythe Hubble Space Telescope (HST). Recent WD studies have been motivated by the new and independent cluster distance (Renzini et al. 1996), age (von Hippel et al. 1995; Richer et al. 1997), and stellar evolution (Koester & Reimers 1996) information that cluster WDs can provide. An important byproduct of these studies has been an estimate of the WD mass contribution in open and globular clusters. The cluster WD mass fraction is of importance for understanding the dynamical state and history of star clusters. It also bears an important connection to the WD mass fractions of the Galactic disk and halo. Current evidence indicates that the open clusters (e.g. von Hippel et al. 1996; Reid this volume) have essentially the same luminosity function (LF) as the solar neighborhood population. The case for the halo is less clear, despite the number of very good globular cluster LFs down to nearly 0.1 solar masses (e.g. Cool et al. 1996; Piotto, this volume), as the field halo LF is poorly known. For most clusters dynamical evolution should cause evaporation of the lowest mass members, biasing clusters to have flatter present-day mass functions (PDMFs) than the disk and halo field populations. Dynamical evolution should also allow cluster WDs to escape, though not in the same numbers as the much lower mass main sequence stars. The detailed connection between cluster PDMFs and the field IMF awaits elucidation from observations and the new combined N-body and stellar evolution models (Tout, this volume). Nevertheless, the WD mass fraction of clusters already provides an estimate for the WD mass fraction of the disk and halo field populations. A literature search to collect cluster WDs and a simple interpretive model follow. This is a work in progress and the full details of the literature search and the model will be published elsewhere.

scholarly journals Seasonal variations in PM10 inorganic composition in the Andean city

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Rasa Zalakeviciute ◽  
Katiuska Alexandrino ◽  
Yves Rybarczyk ◽  
Alexis Debut ◽  
Karla Vizuete ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Inductively Coupled Plasma ◽  
Chemical Elements ◽  
Large Fraction ◽  
Urban Pollution ◽  
Optical Emission ◽  
High Elevation ◽  
Water Soluble ◽  
Wet Season ◽  
Soluble Ions

Abstract Particulate matter (PM) is one of the key pollutants causing health risks worldwide. While the preoccupation for increased concentrations of these particles mainly depends on their sources and thus chemical composition, some regions are yet not well investigated. In this work the composition of chemical elements of atmospheric PM10 (particles with aerodynamic diameters ≤ 10 µm), collected at the urban and suburban sites in high elevation tropical city, were chemically analysed during the dry and wet seasons of 2017–2018. A large fraction (~ 68%) of PM10 composition in Quito, Ecuador is accounted for by water-soluble ions and 16 elements analysed using UV/VIS spectrophotometer and Inductively Coupled Plasma—Optical Emission Spectroscopy (ICP-OES). Hierarchical clustering analysis was performed to study a correlation between the chemical composition of urban pollution and meteorological parameters. The suburban area displays an increase in PM10 concentrations and natural elemental markers during the dry (increased wind intensity, resuspension of soil dust) season. Meanwhile, densely urbanized area shows increased total PM10 concentrations and anthropogenic elemental markers during the wet season, which may point to the worsened combustion and traffic conditions. This might indicate the prevalence of cardiovascular and respiratory problems in motorized areas of the cities in the developing world.

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