About Us
Colloquium Details
Date and time: Thursday, December 10, 2009 at 4:10 PM
Location: 807 Dennison
Speaker: Janice Lee from The Carnegie Observatories
Title/topic: Measuring Star Formation Rates, Near and Far
Abstract:
I will share recent results on the measurement of star formation rates (SFRs) which involve the (mis-)behavior of low-luminosity systems relative to expectations based on our more developed understanding of normal star-forming spiral galaxies. Using a complete, statistical sample of star-forming galaxies within the Local Volume, I evaluate the consistency between SFRs inferred from H-alpha nebular emission and the far ultraviolet non-ionizing continuum. Our analysis probes activities ranging from those that are characteristic of the Milky Way to ultra low SFRs of 0.0001 M_sun/yr. It is established that there is a systematic decline of the integrated H-alpha-to-FUV flux ratio in galaxies less active than the Small Magellanic Cloud. Thus, if standard linear SFR conversion recipes are applied, the UV yields a higher SFR than H-alpha, by factors of two to more than 10, in this regime. It has been argued that such a systematic may be evidence for a non-universal stellar initial mass function. I discuss this and other possible causes of the observed discrepancy. At the end of the talk, I will introduce a comprehensive new campaign we have undertaken to extend H-alpha galaxy surveys to the higher redshift via wide-field narrowband imaging in the near-IR.
Go to the list of current and upcomming colloquia.
See a list of past colloquia.
