PI Highlight
Dr. Allen Shafter
Dr. Allen Shafter, professor and chair of astronomy, studies the properties of a class of explosive star known as Classical Novae.
Since ancient times a widely-held and popular misconception has been that the distant stars are both constant in brightness and eternal. In reality, nothing could be further from the truth. The luminosities of stars vary on all time scales and amplitudes, from tiny and frequent fluctuations in brightness exhibited by run-of-the-mill stars like our sun, to the relatively rare, but colossal explosions of supernovae. The brightnesses of supernovae can, for a brief period of weeks to months, rival the combined luminosity of an entire galaxy containing billions of "normal" stars.
Professor Shafter and his students in the astronomy department at SDSU have been studying another type of explosive variable star known as classical novae. Classical novae, while not as spectacular as supernovae, are nevertheless among the most spectacular cosmic events.
A typical classical nova outburst releases as much energy in a few weeks as the sun does in ten thousand years. All outbursts of classical novae arise not from a single progenitor star, but from a binary star system consisting of two individual stars. One of the stars is a relatively normal star like the sun (but typically of lower mass) in a close orbit with a very dense and compact companion star known as a white dwarf. The orbit is quite compact, and in most cases the entire binary star system could fit within a volume smaller than that of our sun. The close proximity of the stars in combination with the strong gravitational pull of the white dwarf results in the transfer of material from the outer regions of the normal star onto the surface of its white dwarf companion. This material builds up over time (typically thousands of years) before burning explosively, resulting in the nova eruption.
Professor Shafter's research is focused on understanding how the explosions of classical novae in nearby galaxies depend on the detailed properties (e.g., mass, chemical composition, age) of the component stars in the nova binary. This research is currently funded through grants from NASA and the NSF.
Much of Dr. Shafter's work and that of his colleagues takes place at the Mount Laguna Observatory. The Mount Laguna Observatory (MLO) is operated by the SDSU department of astronomy to support its research, training, and educational programs. It is located forty-five miles east of San Diego, at an altitude of 6100 ft. (1859 meters) on the remote eastern edge of the Cleveland National Forest. Currently, there are three telescopes in operation at MLO ranging in size from a 21-in reflector used for public nights and student training to 24-in and 40-in reflectors used for research. In addition, a new 48-in robotic (remotely-operable) telescope is currently under construction.
For further information, Professor Shafter can be reached at shafter@sciences.sdsu.edu or at 619-594-6170.
Further information about MLO can be found at: http://mintaka.sdsu.edu/.
Photos courtesy of Dr. Allen Shafter and Dr. William Welsh.