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Catalog Service:
Hyperfine levels of N_2_H^+^

Short name: J/ApJ/716/1315
IVOA Identifier: ivo://CDS.VizieR/J/ApJ/716/1315
DOI (Digital Object Identifier): 10.26093/cds/vizier.17161315
Publisher: CDSivo://CDS[Pub. ID]
More Info: https://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/716/1315
VO Compliance: Level 2: This is a VO-compliant resource.
Status: active
Registered: 2012 Jun 21 10:24:00Z
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Description


In this paper, we discuss two approximate methods previously suggested for modeling hyperfine spectral line emission for molecules whose collisional transition rates between hyperfine levels are unknown. Hyperfine structure is seen in the rotational spectra of many commonly observed molecules such as HCN, HNC, NH_3_, N_2_H^+^, and C^17^O. The intensities of these spectral lines can be modeled by numerical techniques such as {Lambda}-iteration that alternately solve the equations of statistical equilibrium and the equation of radiative transfer. However, these calculations require knowledge of both the radiative and collisional rates for all transitions. For most commonly observed radio frequency spectral lines, only the net collisional rates between rotational levels are known. For such cases, two approximate methods have been suggested. The first method, hyperfine statistical equilibrium, distributes the hyperfine level populations according to their statistical weight, but allows the population of the rotational states to depart from local thermal equilibrium (LTE). The second method, the proportional method, approximates the collision rates between the hyperfine levels as fractions of the net rotational rates apportioned according to the statistical degeneracy of the final hyperfine levels. The second method is able to model non-LTE hyperfine emission. We compare simulations of N_2_H^+^ hyperfine lines made with approximate and more exact rates and find that satisfactory results are obtained.

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About the Resource Providers

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

Creators:
Keto E.Rybicki G.

Contact Information:
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Observatoire de Strasbourg
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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: 2012 Jul 12 23:20:14Z
  • Created: 2012 Jun 21 10:24:00Z

This resource was registered on: 2012 Jun 21 10:24:00Z
This resource description was last updated on: 2021 Oct 21 00:00:00Z

What This Resource is About

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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/ApJ/716/1315 Literature Reference: 2010ApJ...716.1315K

Related Resources:

Other Related Resources
TAP VizieR generic service(IsServedBy) ivo://CDS.VizieR/TAP [Res. ID]
J/A+A/413/1177 : Spectroscopy of N_2_D^+^ hyperfine structure (Dore+, 2004) ivo://CDS.VizieR/J/A+A/413/1177 [Res. ID]

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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/ApJ/716/1315
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


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