April 25th, 2015
with Dr. Shrinivas Kulkarni – Caltech
John D. & Catherine T. MacArthur Professor of Astronomy and Planetary Science at the California Institute of Technology (Caltech) & Director, Caltech Optical Observatories Abstract of Lecture:
Cosmic explosions were first noted nearly two thousand years ago. However, secure recognition and study began only a hundred years ago. What was once termed as Stella Nova (new stars) are now divided into two major families, novae and supernovae (with real distinct classes in each). Equally the variable stars have a rich phenomenology. Together, supernovae and variable stars have contributed richly to key problems in modern astrophysics: distances to galaxies, cosmography and build-up of elements in the Universe. The Palomar Transient Factory (PTF), an innovative 2-telescope system, was designed to explicitly to chart the transient sky with a particular focus on events which lie in the nova-supernova gap. PTF is now finding an extragalactic transient every 20 minutes and a Galactic (strong) variable every 10 minutes. The results so far: ultra-luminous supernovae as the end of the most massive stars in the Universe, progress in understanding the origin of Ia supernovae (which were used by astronomers to discover dark energy), discovery of new classes or sub-classes of supernovae and identification of curious double degenerates of value to future gravitational wave observatories in space.
