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Astronomy Colloquium - Lauren Campbell, Vanderbilt University
Start Date: 3/28/2016Start Time: 4:30 PM
End Date: 3/28/2016End Time: 5:30 PM

Event Description:

Lauren Campbell, Center for Teaching, Vanderbilt University

"Uncovering the Unbound Stellar Population in and Around the Milky Way"

A significant fraction of a galaxy's light may come from a population of unbound stars, and this population can inform us about the dynamical state and stellar content of the galaxy. In galaxy clusters this unbound fraction is known as intracluster light (ICL), identified as a diffuse excess of light in the outskirts of the galaxy. ICL has been observed around distant galaxies and a similar intracluster stellar glow ought to exist around the Milky Way.

We developed a technique to identify distant M-giants within the Sloan Digital Sky Survey (SDSS) based solely on color. Using this technique, we identified 700 candidate M-giant stars at intragroup distances, beyond 300 kpc, that we call intragroup stars (IGS). These IGS may constitute rare tracers of an underlying ICL population surrounding the Milky Way. One possible explanation for the origin of these IGS is that they were ejected from the center of the Galaxy through interactions with our supermassive black hole as hypervelocity stars (HVSs). There are only 18 confirmed HVSs and all are young, massive, B-type stars. We identify candidate HVSs from a sample of SDSS G- and K-dwarfs. Using the observed positions and velocities, we calculate the orbits of these candidates in order to determine their place of origin within the Galaxy. We find that nearly half of the candidates exceed their escape velocities with at least 98% probability and no candidate's orbit is consistent with a Galactic Center origin.

Monday, March 28, 2016 4:30 PM in Science Center 128 Light refreshments will be served
Location Information:
*Swarthmore College - Science Center
Room: Science Center 128
Contact Information:
Name: Department of Physics & Astronomy
Phone: 610-328-8258
Open To
The Public

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