Hα Survey of Emission Line Regions in M33 and Local Group Dwarf Galaxies

Type Conference Paper
Names Cindy Blaha, T. Johnson, R. Cawthon, M. Dixon, C. Murray, P. Massey, P. Hodge
Proceedings Title Bulletin of the American Astronomical Society
Conference Name AAS Meeting #217, #251.12
Volume 43
Pages 25112
Date January 1, 2011
URL http://adsabs.org/2011AAS.21725112B
Library Catalog labs.adsabs.harvard.edu
Abstract We present the results of a survey of H α emission line regions in M33 and seven dwarf galaxies in the Local Group (NGC6822, IC10, WLM, Sextans A and B, Phoenix and Pegasus). Using data from the Local Group Galaxy Survey (LGGS - see Massey et al, 2006)), we used continuum-subtracted Hα emission line images to define emission regions with a faint flux limit of 10 -17 ergs-sec-1-cm-2 above the background. We have obtained photometric measurements for over 4000 H α emission regions in M33 and five of the seven dwarf galaxies. Using these regions, with boundaries defined by their H α-emission, we also determined fluxes for the continuum-subtracted [OIII] and [SII] images and constructed a catalog of H α fluxes, region sizes and [OIII]/ H α and [SII]/ H α line ratios. The HII region luminosity functions and size distributions for spiral galaxy M33 are compared with those of the dwarf galaxies NGC 6822 and IC10. For M33, the average [SII]/ H α line ratios, plotted as a function of galactocentric radius, display a linear trend with a very shallow slope. The galaxy-wide averages of [SII]/ H α line ratios correlate with the masses of the dwarf galaxies following the previously established dwarf galaxy mass-metallicity relationship. An interactive catalog of these LGGS emission line surveys will be made available on-line.
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