Saturday Oct 19, 2019
Albuquerque, NM 87106
Contact:The Albuquerque Astronomical Society
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TAAS General Meeting
Saturday, October 19 - 7:00pm
Regener Hall, UNM Campus
Free and open to the public
“White Dwarfs: The Most Wonderful of All Stars!” - Dr. John McGraw, Featured Speaker(Text by Dr. McGraw)
In about 5 billion years, our Sun will end its normal lifetime of fusing hydrogen and helium to heavier atoms, such as carbon and oxygen, and finally end its 10 billion-year life as a white dwarf star.
Dr. McGraw will describe the stellar evolution to the white dwarf stage of stars like our Sun. This structure is uniquely interesting because, as heavier atoms are created by nuclear fusion - the energy source of our Sun - the inner core becomes stratified, with heavier nuclei gravitationally “falling” to the center of the star. This infall halts (at a most interesting place!) when the core of the Sun is about the size of the Earth.When it halts, at that point, the core of our Sun becomes a white dwarf, and will remain a white dwarf essentially for the lifetime of the universe! Exciting(!!) laboratory experiments describing the “atmospheres” of these white dwarf stars are being carried out at Sandia National Laboratories, right here in River City!
But wait! There’s more! Just as evolving giant stars pulsate at certain times during their lifetime, so too do white dwarf stars … but their pulsations are very different from “normal” stars. They are “nonradial pulsations.” (This discovery was the topic of McGraw's PhD dissertation at the University of Texas many years ago!)
As preparatory homework, consider what the Milky Way galaxy will look like in, say, 100 billion years, when most of the stars we see at night have evolved to become white dwarfs!
Biography: McGraw did his PhD at the University of Texas at Austin, with lots of observations made at McDonald Observatory. He was at the University of Arizona Steward Observatory in Tucson for about 13 years, and has been Professor of Physics and Astronomy in the University of New Mexico for 25 years
He became Professor Emeritus in UNM last July and, in addition to astronomical research, is operating a small company, J. T. McGraw and Associates (JTMA) which uses optimized optical techniques to detect Earth-orbiting satellites and debris and provide robust, continuous surveillance of Earth orbital space.
See www.taas.org for map