A Caltech Library Service

The Paα Luminosity Function of H II Regions in Nearby Galaxies from HST/NICMOS

Liu, Guilin and Calzetti, Daniela and Kennicutt, Robert C., Jr. and Schinnerer, Eva and Sofue, Yoshiaki and Komugi, Shinya and Egusa, Fumi and Scoville, Nicholas Z. (2013) The Paα Luminosity Function of H II Regions in Nearby Galaxies from HST/NICMOS. Astrophysical Journal, 772 (1). Art. No. 27. ISSN 0004-637X.

PDF - Published Version
See Usage Policy.

PDF - Submitted Version
See Usage Policy.


Use this Persistent URL to link to this item:


The H II region luminosity function (LF) is an important tool for deriving the birthrates and mass distribution of OB associations and is an excellent tracer of the newly formed massive stars and associations. To date, extensive work (predominantly in Hα) has been done from the ground, which is hindered by dust extinction and the severe blending of adjacent (spatially or in projection) H II regions. Reliably measuring the properties of H II regions requires a linear resolution <40 pc, but analyses satisfying this requirement have been done only in a handful of galaxies, so far. As the first space-based work using a galaxy sample, we have selected 12 galaxies from our HST/NICMOS Paα survey and studied the LF and size distribution of H II regions both in individual galaxies and cumulatively, using a virtually extinction-free tracer of the ionizing photon rate. The high angular resolution and low sensitivity to diffuse emission of NICMOS also offer an advantage over ground-based imaging by enabling a higher degree of de-blending of the H II regions. We do not confirm the broken power-law LFs found in ground-based studies. Instead, we find that the LFs, both individual and co-added, follow a single power law dN(L)/dln L ∝ L^–1, are consistent with the mass function of star clusters in nearby galaxies, and are in agreement with the results of the existing analyses with Hubble Space Telescope (HST) data. The individual and co-added size distributions of H II regions are both roughly consistent with dN(D)/dln D ∝ D^–3, but the power-law scaling is probably contaminated by blended regions or complexes.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Calzetti, Daniela0000-0002-5189-8004
Kennicutt, Robert C., Jr.0000-0001-5448-1821
Schinnerer, Eva0000-0002-3933-7677
Scoville, Nicholas Z.0000-0002-0438-3323
Additional Information:© 2013 American Astronomical Society. Received 2013 April 9; accepted 2013 May 21; published 2013 July 2. We thank the anonymous referee for a careful reading of the manuscript. Partial support for program GO-11080 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. This research has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. We also acknowledge the usage of the HyperLeda database ( Facility: HST (NICMOS). Based on observations taken with the NASA/ESA Hubble Space Telescope obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS5-26555. These observations are associated with program GO-11080.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
NASANAS 5-26555
Subject Keywords:galaxies: individual; H II regions
Issue or Number:1
Record Number:CaltechAUTHORS:20130820-091646576
Persistent URL:
Official Citation:The Paα Luminosity Function of H II Regions in Nearby Galaxies from HST/NICMOS Guilin Liu et al. 2013 ApJ 772 27
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:40727
Deposited By: Jason Perez
Deposited On:21 Aug 2013 16:02
Last Modified:09 Mar 2020 13:18

Repository Staff Only: item control page