Refined sample of Lyman excess H II regions Virtual Observatory Resource

Authors
  1. Marshall B.
  2. Kerton C.R.
  3. Published by
    CDS
Abstract

A large number (67) of the compact/ultra-compact HII regions identified in the Coordinated Radio and Infrared Survey for High-Mass Star Formation catalogue were determined to be powered by a Lyman continuum flux in excess of what was expected given their corresponding luminosity. In this study we attempt to reasonably explain the Lyman excess phenomenon in as many of the 67 HII regions as possible through a variety of observational and astrophysical means including new luminosity estimates, new Herschel photometry, new distance determinations, the use of different models for dust and ionized gas covering factors, and the use of different stellar calibrations. This phenomenon has been observed before; however, the objects shown to exhibit this behaviour in the literature have decidedly different physical properties than the regions in our sample, and thus the origin of the excess is not the same. We find that the excess can be reproduced using OB stellar atmosphere models that have been slightly modified in the extreme ultraviolet. Though the exact mechanism producing the excess is still uncertain, we do find that a scaled up magnetospheric accretion model, often used to explain similar emission from T Tauri stars, is unable to match our observations. Our results suggest that the Lyman excess may be associated with younger HII regions, and that it is more commonly found in early B-type stars. Our refined sample of 24 Lyman excess HII regions provides an ideal sample for comparative studies with regular HII regions, and can act as the basis for the further detailed study of individual regions.

Keywords
  1. h-ii-regions
  2. millimeter-astronomy
  3. submillimeter-astronomy
Bibliographic source Bibcode
2018MNRAS.478.5579M
See also HTML
https://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/478/5579
IVOA Identifier IVOID
ivo://CDS.VizieR/J/MNRAS/478/5579
Document Object Identifer DOI
doi:10.26093/cds/vizier.74785579

Access

IVOA Table Access TAP
https://tapvizier.cds.unistra.fr/TAPVizieR/tap
Run SQL-like queries with TAP-enabled clients (e.g., TOPCAT).
IVOA Cone Search SCS
For use with a cone search client (e.g., TOPCAT).
https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/478/5579/table4?
https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/478/5579/table4?
http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/478/5579/table4?

History

2022-02-08T12:50:24Z
Resource record created
2022-02-08T12:50:24Z
Created
2024-08-18T20:20:26Z
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