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Event Number 2864

  Monday, December 3rd, 2012

Special Lunch Astronomy Talk
"H-alpha Dots: A Catalog of Faint Emission-line Objects Discovered in Narrowband Images"
Time: 12:00 pm
Place: 4421 Sterling Hall
Speaker: Jessica Kellar, Darthmouth College
Abstract: I discovered a number of isolated and compact sources of emission (aEurooeH-alpha dotsaEuro) in a narrow-band H-alpha survey. These H-alpha dots could be (1) isolated extra-galactic HII regions associated with a nearby larger galaxy, (2) dwarf star-forming galaxies, or (3) background galaxies, where another strong emission-line such as [OIII]5007 has redshifted into the H-alpha filter. Based on follow-up spectra taken at the MDM 2.4 meter telescope and HET, I determined that the H-alpha dots are a combination of nearby (z~0.01) dwarf star-forming galaxies and intermediate-redshift (mostly at z~0.3) starforming galaxies and AGN. I will discuss the star-formation properties, environments, and metallicities of the dwarf galaxies. The star-forming galaxies at z~0.3 are very metal-poor, which suggests that they may be recently formed. I will discuss the insights this diverse sample of galaxies from the H-alpha dot survey can give us about galaxy evolution.
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