Hα Survey of Emission Line Regions in M33 and Local Group Dwarf Galaxies
Blaha, Cindy ( Carleton College ); Johnson, T. ( Carleton College ); Cawthon, R. ( Carleton College ); Dixon, M. ( Carleton College ); Murray, C. ( Carleton College ); Massey, P. ( Lowell Observatory ); Hodge, P. ( University of Washington ) show affiliations
American Astronomical Society, AAS Meeting #217, id.251.12; Bulletin of the American Astronomical Society, Vol. 43, 2011
Published in Jan 2011
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.
(c) 2011: American Astronomical Society