Physics Colloquium - Friday, Jan. 25th, 2008, 4:00 P.M.
Center; Refreshments at 3:30 P.M. in
The Discovery of a New δ-Scuti Variable in Cassiopeia
Department of Physics
Star variability not only gives us a greater understanding of distances in our
universe but also an insight into how stars behave at different evolutionary stages.
There are roughly 40,000 known variables in our galaxy, of which, there are only a
handful of pulsating variables that can be used to determine distances based on
their period-luminosity relation. The introduction of the CCD detectors along with
improvements to instrumentation has led to the discovery of a sub-class of pulsators
known as δ-Scutis which occupy the extreme lower end of the instability strip on the
Hertzsprung-Russell diagram. Since δ-Scutis have pulsation periods along the order of
1 to 3 hours and amplitudes no greater than 0.1 magnitude, CCD photometry has played
a vital role in their detection. Given the comparatively small population of only
540, very little is known about δ-Scutis because they are difficult to detect and
exhibit both radial and non-radial pulsation modes. Therefore it is important for
our understanding of this under-studied type of variable to collect and analyze a
much larger sample. On October 4th, 2007 a new 12th magnitude δ-Scuti was discovered
and added to the list by Emory Universitys Physics Department. Proving that even
through modest light pollution a viable scientific contribution can be made towards
the study of stellar pulsation.