Cosmic phylogeny: reconstructing the chemical history of the solar neighbourhood with an evolutionary tree

Jofré, P.; Das, Payel; Bertranpetit, Jaume; Foley, Robert

doi:10.1093/mnras/stx075

Cited by 45 publications

(61 citation statements)

References 65 publications

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“…A new way of using chemical abundances to study the chemical evolution of stellar populations has been proposed by Jofré et al (2017a), i.e. to apply phylogenetic techniques from biology on chemical abundances (as "a stellar DNA") to construct evolutionary trees.…”

Section: Chemical Tagging and Phylogenetic Studiesmentioning

confidence: 99%

High-precision stellar abundances of the elements: methods and applications

Nissen

Gustafsson

2018

Astron Astrophys Rev

102

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Efficient spectrographs at large telescopes have made it possible to obtain high-resolution spectra of stars with high signal-to-noise ratio and advances in model atmosphere analyses have enabled estimates of high-precision differential abundances of the elements from these spectra, i.e. with errors in the range 0.01 -0.03 dex for F, G, and K stars.Methods to determine such high-precision abundances together with precise values of effective temperatures and surface gravities from equivalent widths of spectral lines or by spectrum synthesis techniques are outlined, and effects on abundance determinations from using a 3D non-LTE analysis instead of a classical 1D LTE analysis are considered.The determination of high-precision stellar abundances of the elements have led to the discovery of unexpected phenomena and relations with important bearings on the astrophysics of galaxies, stars, and planets, i.e. i) Existence of discrete stellar populations within each of the main Galactic components (disk, halo, and bulge) providing new constraints on models for the formation of the Milky Way. ii) Differences in the relation between abundances and elemental condensation temperature for the Sun and solar twins suggesting dust-cleansing effects in proto-planetary disks and/or engulfment of planets by stars; iii) Differences in chemical composition between binary star components and between members of open or globular clusters showing that star-and cluster-formation processes are more complicated than previously thought; iv) Tight relations between some abundance ratios and age for solar-like stars providing new constraints on nucleosynthesis and Galactic chemical evolution models as well as the composition of terrestrial exoplanets.We conclude that if stellar abundances with precisions of 0.01 -0.03 dex can be achieved in studies of more distant stars and stars on the giant and supergiant branches, many more interesting future applications, of great relevance to stellar and galaxy evolution, are probable. Hence, in planning abundance surveys, it is important to carefully balance the need for large samples of stars against the spectral resolution and signal-to-noise ratio needed to obtain high-precision abundances. Furthermore, it is an advantage to work differentially on stars with similar atmospheric parameters, because then a simple 1D LTE analysis of stellar spectra may be sufficient. However, when determining high-precision absolute abundances or differential abundance between stars having more widely different parameters, e.g. metal-poor stars compared to the Sun or giants to dwarfs, then 3D non-LTE effects must be taken into account.

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Section: Chemical Tagging and Phylogenetic Studiesmentioning

confidence: 99%

High-precision stellar abundances of the elements: methods and applications

Nissen

Gustafsson

2018

Astron Astrophys Rev

102

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“…The origin of these intermediate- [Mg/Fe] populations is difficult to discern. It is possible that they are chemically related to the high-[Mg/Fe] metal-poor stars (e.g., Haywood et al 2016), are a distinct population (e.g., Jofré et al 2017), or could also result from extra mixing along the RGB for metal-rich populations (Masseron & Gilmore 2015 it is also uncertain to which sequence (or both) these stellar populations belong. It has been argued that what we identify as the thick disk in the chemical plane is not a distinct phase of the disk evolution, but is instead the chemical evolution track of stellar populations from the inner Galaxy that is brought to the solar neighborhood through radial mixing processes (Haywood et al 2013).…”

Section: Introductionmentioning

confidence: 99%

The AMBRE project: The thick thin disk and thin thick disk of the Milky Way

Hayden

Recio–Blanco

Laverny

et al. 2017

A&A

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We analyze 494 main sequence turnoff and subgiant stars from the AMBRE:HARPS survey. These stars have accurate astrometric information from Gaia DR1, providing reliable age estimates with relative uncertainties of ±1 or 2 Gyr and allowing precise orbital determinations. The sample is split based on chemistry into a low-[Mg/Fe] sequence, which are often identified as thin disk stellar populations, and high-[Mg/Fe] sequence, which are often associated with thick disk stellar populations. We find that the high- outer disk populations, respectively; radial mixing causes both populations to be observed in situ at the solar position. Based on these results, we emphasize that it is important to be clear in defining what populations are being referenced when using the terms thin and thick disk, and that ideally the term thick disk should be reserved for purely geometric definitions to avoid confusion and be consistent with definitions in external galaxies.

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“…A first phylogenetic analysis of real stars in our Galaxy was performed by Jofré et al (2017). Their goal was not to classify stars following the chemical tagging objectives, that is to group stars that were born together, but to obtain an evolutionary scenario for stars in the solar neighborhood.…”

Section: Introductionmentioning

confidence: 99%

A phylogenetic approach to chemical tagging

Blanco-Cuaresma

Fraix-Burnet

2018

A&A

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Context. The chemical tagging technique is a promising approach to reconstruct the history of the Galaxy by only using stellar chemical abundances. Different studies have undertaken this analysis and they raised several challenges. Aims. Using a sample of open clusters stars, we wish to address two issues: minimize chemical abundance differences which origin is linked to the evolutionary stage of the stars and not their original composition; 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 M67 as reference (new approach). These abundances were then used to perform two phylogenetic analyses, cladistics (Maximum Parsimony) and Neighbour-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 M67. We find a set of eight chemical elements that yields the best result, and discuss the possible reasons for them 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.

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Cosmic phylogeny: reconstructing the chemical history of the solar neighbourhood with an evolutionary tree

Cited by 45 publications

References 65 publications

High-precision stellar abundances of the elements: methods and applications

High-precision stellar abundances of the elements: methods and applications

The AMBRE project: The thick thin disk and thin thick disk of the Milky Way

A phylogenetic approach to chemical tagging

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