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Testing the chemical tagging technique with open clusters

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González Hernández, J. I. and Montes Gutiérrez, David and Tabernero Guzmán, Hugo Martín (2015) Testing the chemical tagging technique with open clusters. Astronomy and astrophysics, 577 . A47/1-A47/15. ISSN 0004-6361

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Official URL: http://dx.doi.org/10.1051/0004-6361/201425232


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Abstract

Context. Stars are born together from giant molecular clouds and, if we assume that the priors were chemically homogeneous and well-mixed, we expect them to share the same chemical composition. Most of the stellar aggregates are disrupted while orbiting the Galaxy and most of the dynamic information is lost, thus the only possibility of reconstructing the stellar formation history is to analyze the chemical abundances that we observe today. Aims. The chemical tagging technique aims to recover disrupted stellar clusters based merely on their chemical composition. We evaluate the viability of this technique to recover co-natal stars that are no longer gravitationally bound. Methods. Open clusters are co-natal aggregates that have managed to survive together. We compiled stellar spectra from 31 old and intermediate-age open clusters, homogeneously derived atmospheric parameters, and 17 abundance species, and applied machine learning algorithms to group the stars based on their chemical composition. This approach allows us to evaluate the viability and efficiency of the chemical tagging technique. Results. We found that stars at different evolutionary stages have distinct chemical patterns that may be due to NLTE effects, atomic diffusion, mixing, and biases. When separating stars into dwarfs and giants, we observed that a few open clusters show distinct chemical signatures while the majority show a high degree of overlap. This limits the recovery of co-natal aggregates by applying the chemical tagging technique. Nevertheless, there is room for improvement if more elements are included and models are improved.


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© ESO 2015. This work was partially supported by the Gaia Research for European Astronomy Training (GREAT-ITN) Marie Curie network, funded through the European Union Seventh Framework Programme [FP7/2007-2013] under grant agreement n. 264895. U.H. and A.J.K. acknowledge support from the Swedish National Space Board (Rymdstyrelsen). I.S.R. gratefully acknowledges the support provided by the Gemini-CONICYT project 32110029. All the software used in the data analysis were provided by the Open Source community.

Uncontrolled Keywords:Old open clusters; Late-type stars; Lte line formation; Model atmospheres; Atomic diffusion; Galactic disk; Molecular clouds; Abundances; Parameters; Metallicity
Subjects:Sciences > Physics > Astrophysics
Sciences > Physics > Astronomy
ID Code:30821
Deposited On:11 Jun 2015 15:11
Last Modified:10 Dec 2018 15:05

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