HRDS III. HII region kinematic distances Virtual Observatory Resource

Authors
  1. Anderson L.D.
  2. Bania T.M.
  3. Balser D.S.
  4. Rood R.T.
  5. Published by
    CDS
Abstract

Using the H I emission/absorption method, we resolve the kinematic distance ambiguity and derive distances for 149 of 182 (82%) H II regions discovered by the Green Bank Telescope H II Region Discovery Survey (GBT HRDS). The HRDS is an X-band (9 GHz, 3 cm) GBT survey of 448 previously unknown H II regions in radio recombination line and radio continuum emission. Here, we focus on HRDS sources from 67{deg}>={ell}>=18{deg}, where kinematic distances are more reliable. The 25 HRDS sources in this zone that have negative recombination line velocities are unambiguously beyond the orbit of the Sun, up to 20kpc distant. They are the most distant H II regions yet discovered. We find that 61% of HRDS sources are located at the far distance, 31% at the tangent-point distance, and only 7% at the near distance. "Bubble" H II regions are not preferentially located at the near distance (as was assumed previously) but average 10 kpc from the Sun. The HRDS nebulae, when combined with a large sample of H II regions with previously known distances, show evidence of spiral structure in two circular arc segments of mean Galactocentric radii of 4.25 and 6.0kpc. We perform a thorough uncertainty analysis to analyze the effect of using different rotation curves, streaming motions, and a change to the solar circular rotation speed. The median distance uncertainty for our sample of H II regions is only 0.5 kpc, or 5%. This is significantly less than the median difference between the near and far kinematic distances, 6 kpc. The basic Galactic structure results are unchanged after considering these sources of uncertainty.

Keywords
  1. h-ii-regions
  2. radio-astronomy
  3. surveys
  4. stellar-distance
Bibliographic source Bibcode
2012ApJ...754...62A
See also HTML
https://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/754/62
IVOA Identifier IVOID
ivo://CDS.VizieR/J/ApJ/754/62
Document Object Identifer DOI
doi:10.26093/cds/vizier.17540062

Access

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http://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/754/62
https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/754/62
http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/754/62
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For use with a cone search client (e.g., TOPCAT).
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https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/754/62/table1?
http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/754/62/table1?

History

2014-03-31T10:35:35Z
Resource record created
2014-03-31T10:35:35Z
Created
2017-09-19T14:24:05Z
Updated

Contact

Name
CDS support team
Postal Address
CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France
E-Mail
cds-question@unistra.fr