Astronomy Seminar--Leo P: An Extremely Metal Deficient Galaxy & Other Strange Stories

3:00 PM  - 4:00 PM
Tuesday Feb 5, 2013
Room 150, Olin-Rice Science Center

Danielle Berg, Department of Astronomy, University of Minnesota.

Leo P is a strange dwarf irregular galaxy. A rare gem discovered recently in the Arecibo ALFALFA survey with a single bright star-forming (H II) region. KPNO 4-m and LBT/MODS spectroscopic observations were obtained of this H II region. We are able to accurately measure the temperature sensitive [O III] λ4363 line and determine a “direct” oxygen abundance that shows Leo P is an extremely metal deficient (XMD) galaxy. A surprise to all, Leo P turns out to be one of the most metal deficient galaxies of all! For its estimated luminosity, Leo P is consistent with the relationship between luminosity and oxygen abundance seen in nearby dwarf galaxies. 

The oxygen abundance is exciting enough, but the other elements do not disappoint. A helium mass fraction was derived which compares well with the WMAP + BBN prediction for the primordial helium abundance; an independent observed confirmation of theoretical predictions. Leo P also shows normal α element abundances (Ne/O, S/O, and Ar/O) when compared to other XMD galaxies, but elevated N/O, consistent with the “delayed release” hypothesis for N/O abundances. 

What could this mean? I will tell you of KPNO nitrogen, LBT nitrogen, primary nitrogen, secondary nitrogen. 

“From there to here, from here to there, funny things are everywhere.” (Dr. Seuss)

This event is for: Students, Staff and Faculty

Sponsored By: Physics & Astronomy

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