NOAO >   Observing Info >   Approved Programs >   2002A-0243

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Proposal Information for 2002A-0243


PI: Salman Hameed, Five College Astronomy Department, shameed@earth.ast.smith.edu
Address: Clark Science Center, McConnell 410B, Northampton, MA 01063, U.S.A

CoI: David Thilker, National Radio Astronomy Observatory
CoI: Nick Devereux, Embry-Riddle Aeronautical University
CoI: Rene' Walterbos, New Mexico State University

Title: HII Region Luminosity Functions of Spiral Galaxies

Abstract: We are proposing to use the 4 meter telescope at KPNO to obtain H(alpha) images for a representative northern hemisphere sample of bright, nearby, spiral (Sa-Scd) galaxies. The images will be used to derive HII region luminosity functions, diffuse fractions, H(alpha) equivalent widths, and H(alpha) luminosities. These observations will compliment our HII region LF survey of the southern hemisphere spiral galaxies. The general purpose of the survey is to investigate and elucidate changing perceptions concerning the nature and origin of the Hubble Sequence. Preliminary results from our H(alpha) imaging survey of early- type(Sa-Sab) spirals have revealed them to be a heterogenous class of objects. Contrary to popular perception, our images have identified a significant fraction (25-30%) of Sa-Sab galaxies with massive star formation rates that rival the most prolifically star forming late-type spirals. Furthermore, the wide range of star formation activity apparent for early-type spirals is reflected in a correspondingly wide variety of HII region luminosity function shapes. Our early results have also detected significant differences between the properties of early-type spirals located in the northern and southern hemispheres. We have extended our survey to include Sb-Sbc and Sc-Scd galaxies. In order to avoid any hemispheric bias, such as seen in early-type spirals, we are requesting time to obtain H(alpha) images for a representative sample of northern hemisphere spiral galaxies.


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