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A Statistical Comparison of the Near Infrared Emission with the Hα Emission from the HII regions of NGC4321, NGC4736 and NGC4254

Part of: IAU Issue 315 - From Interstellar Clouds...

Published online by Cambridge University Press:  12 September 2016

J.E. Beckman ,
S.J. Chan ,
A. Li  and
J. Borissova
J.E. Beckman
Affiliation:
Instituto de Astrofisica de Canarias 38205 La Laguna, Spain. email: jeb@iac.es CSIC, 28006 Madrid, Spain Department of Astrophysics, University of La Laguna, E-38200 La Laguna, Tenerife, Spain
S.J. Chan
Affiliation:
Instituto de Astrofisica de Canarias 38205 La Laguna, Spain. email: jeb@iac.es Millennium Institute of Astrophysics, Santiago, Chile email: jchan@astro.puc.cl Instituto de Astrofisica, Pontificia Universidad Catolica de Chile, Santiago, Chile
A. Li
Affiliation:
Unversity of Missouri, Columbia, USA
J. Borissova
Affiliation:
Millennium Institute of Astrophysics, Santiago, Chile email: jchan@astro.puc.cl Departamento de Fsica y Astronoma, Universidad de Valparaso, Valparaso, Chile
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Abstract

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We report on our ongoing project “Statistical studies of HII regions in the nearby extra-galaxies”. We present an overview of our detailed study of warm dust in the nearby Galaxy NGC 4321 (M100), measuring the flux values in the 4 Spitzer-IRAC bands of some 275 HII regions in M100. In addition, we present new measurements of the flux values in the 4 Spitzer-IRAC bands of a complete sample of 70 isolated luminous HII regions in NGC 4736 and 157 regions in NGC 4254. We study the relations between the Hα luminosity and the near-IR luminosity and temperature of HII regions in the three galaxies. We estimate the near-IR luminosities and compare them with the Hα luminosities from archive and literature sources. We find a linear relation between the Hα luminosity and the IRAC luminosity for the HII regions, but no apparent relation between the luminosity and the colour temperature of the regions in any of the three galaxies. The colour temperatures of regions especially in M100 and NGC4254 are confined to a surprisingly narrow range, with a small fraction forming a higher temperature tail to the distribution. These results give new insight into the size function and the 3D distribution of the dust in these regions, and we propose scenarios to explain them.

Keywords

galaxies: HII regionsgalaxies:individual(M100,NGC4736,NGC4254)galaxies: NIR emssion
Type
Poster Papers
Information
Proceedings of the International Astronomical Union , Volume 11 , Symposium S315: From Interstellar Clouds to Star-Forming Galaxies: Universal Processes? , August 2015 , E8
Copyright
Copyright © International Astronomical Union 2015 

References

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