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Resource Record Summary

Catalog Service:
Inelastic H-atom collisions NLTE corrections

Short name: J/A+A/618/A141
IVOA Identifier: ivo://CDS.VizieR/J/A+A/618/A141
DOI (Digital Object Identifier): 10.26093/cds/vizier.36180141
Publisher: CDSivo://CDS[Pub. ID]
More Info: https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/618/A141
VO Compliance: Level 2: This is a VO-compliant resource.
Status: active
Registered: 2018 Oct 22 07:45:36Z
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Description


Determination of high-precision abundances of late-type stars has been and always will be an important goal of spectroscopic studies, which requires accurate modeling of their stellar spectra with non-local thermodynamic equilibrium (NLTE) radiative transfer methods. This entails using up-to-date atomic data of the elements under study, which are still subject to large uncertainties. We investigate the role of hydrogen collisions in NLTE spectral line synthesis, and introduce a new general empirical recipe to determine inelastic charge transfer (CT) and bound-bound hydrogen collisional rates. This recipe is based on fitting the energy functional dependence of published quantum collisional rate coefficients of several neutral elements (BeI, NaI, MgI, AlI, SiI and CaI) using simple polynomial equations. We perform thorough NLTE abundance calculation tests using our method for four different atoms, Na, Mg, Al and Si, for a broad range of stellar parameters. We then compare the results to calculations computed using the published quantum rates for all the corresponding elements. We also compare to results computed using excitation collisional rates via the commonly used Drawin equation for different fudge factors, SH, applied. We demonstrate that our proposed method is able to reproduce the NLTE abundance corrections performed with the quantum rates for different spectral types and metallicities for representative NaI and AlI lines to within 0.05dex and 0.03dex, respectively. For MgI and SiI lines, the method performs better for the cool giants and dwarfs, while larger discrepancies up to 0.20dex could be obtained for some lines for the subgiants and warm dwarfs. We obtained larger NLTE correction differences between models incorporating Drawin rates relative to the quantum models by up to 0.40dex. These large discrepancies are potentially due to ignoring either or both CT and ionization collisional processes by hydrogen in our Drawin models.Our general empirical fitting method (EFM) for estimating hydrogen collision rates performs well in its ability to reproduce, within narrow uncertainties, the abundance corrections computed with models incorporating quantum collisional rates. It performs generally best for the cool and warm dwarfs, with slightly larger discrepancies obtained for the giants and subgiants. It could possibly be extended in the future to transitions of the same elements for which quantum calculations do not exist, or, in the absence of published quantum calculations, to other elements as well.

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About the Resource Providers

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Publisher: CDSivo://CDS[Pub. ID]

Creators:
Ezzeddine R.Merle T.Plez B.Gebran M.Thevenin F.Van der Swaelmen M.

Contact Information:
X CDS support team
Email: cds-question at unistra.fr
Address: CDS
Observatoire de Strasbourg
11 rue de l'Universite
F-67000 Strasbourg
France

Status of This Resource

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Version: n/a
Availability: This is an active resource.
  • This service provides only public data.
Relevant dates for this Resource:
  • Updated: 2018 Nov 05 10:52:51Z
  • Created: 2018 Oct 22 07:45:36Z

This resource was registered on: 2018 Oct 22 07:45:36Z
This resource description was last updated on: 2021 Oct 21 00:00:00Z

What This Resource is About

This section describes what the resource is, what it contains, and how it might be relevant.

Resource Class: CatalogService
This resource is a service that provides access to catalog data. You can extract data from the catalog by issuing a query, and the matching data is returned as a table.
Resource type keywords:
  • Catalog
Subject keywords:
  • Atomic physics
Intended audience or use:
  • Research: This resource provides information appropriate for supporting scientific research.
More Info: https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/618/A141 Literature Reference: 2018A&A...618A.141E

Related Resources:

Other Related Resources
TAP VizieR generic service(IsServedBy) ivo://CDS.VizieR/TAP [Res. ID]

Data Coverage Information

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Rights and Usage Information

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Available Service Interfaces

Custom Service

This is service that does not comply with any IVOA standard but instead provides access to special capabilities specific to this resource.

VO Compliance: Level 2: This is a VO-compliant resource.
Available endpoints for this service interface:
Custom Service

This is service that does not comply with any IVOA standard but instead provides access to special capabilities specific to this resource.

VO Compliance: Level 2: This is a VO-compliant resource.
Available endpoints for this service interface:
  • URL-based interface: http://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/618/A141
Table Access Protocol - Auxiliary ServiceXX

This is a standard IVOA service that takes as input an ADQL or PQL query and returns tabular data.

VO Compliance: Level 2: This is a VO-compliant resource.
Available endpoints for the standard interface:
  • http://tapvizier.cds.unistra.fr/TAPVizieR/tap


Developed with the support of the National Science Foundation
under Cooperative Agreement AST0122449 with the Johns Hopkins University
The NAVO project is a member of the International Virtual Observatory Alliance

This NAVO Application is hosted by the Space Telescope Science Institute

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