Science Seminars

1/28/2010 – The Solar Oxygen Problem: Crisis, Catastrophe, or Opportunity?

Speaker: Tom Ayres (CASA)
Date: Thursday, Jan 28, 2010
Time: 4:00pm
Location: LSTB 299

Seminar Abstract:

Over the past decade, the recommended solar oxygen abundance has declined rather precipitously, from a high of 850 ppm in the late 1970’s to the current value of around 450 ppm. At the rate of decline since 2001, in fact, the Sun will run out of oxygen circa 2016. Some might call this as a crisis. Indeed, certain elements of the solar community view the new low oxygen abundance as a catastrophe, because it ruins the previous excellent agreement between theoretical envelope models of the Sun and internal sound speed profiles derived from seismic measurements at the surface. Others see the solar oxygen problem as an opportunity: to test the limits of our ability to extract meaningful fundamental properties from our nearby star. If solar physicists can’t agree on solar abundances, our darkside colleagues will be somewhat limited in their ability to judge whether stellar abundances are normal or unusual. In this talk, I will review the evolution of the solar oxygen abundance over the past three decades, and describe several recent breakthroughs that have helped remove previous glaring disagreements between molecular and atomic tracers of oxygen in the Sun. At the same time, inexplicable differences persist between the two major groups currently pursuing the oxygen problem, reminding one of the two distinct camps in the 1970’s and 1980’s promoting factor-of-two different Hubble constants, demonstrating that “cultural” factors in science sometimes can be as important as hard evidence.