WFU Physics Colloquium

TITLE: The Young Solar Analogs Project: How did a violent young Sun affect the development of life on Earth?

SPEAKER: Professor Richard O. Gray ,

TIME: Wednesday February 24, 2016 at 4:00 PM

PLACE: Room 101 Olin Physical Laboratory

The earliest geological records indicate that life first developed on our planet 3.8 Gyr ago, or perhaps even earlier. At that time the Sun was a dangerous star to be around -- its X-ray and far-ultraviolet fluxes were many times that of today; it varied by up to 5% in its optical output, which would cause climate chaos today; and it produced frequent and powerful flares. While the early Earth's atmosphere and magnetic field would have offered some degree of protection from high-energy radiation and particles, the lack of an ozone layer meant that the surface of the earth would have been exposed to orders of magnitude higher fluxes of biologically damaging near-UV (UV-B and UV-C) radiation than at present, effectively sterilizing the surface of the planet. The Young Solar Analogs project, which has been active since 2007, monitors 30 young solar-type stars both spectroscopically and photometrically in an attempt to better understand the space environment of the early Earth, and by extension planets in habitable zones in other solar systems. I will review some of the major results of this project, and discuss how we hope to monitor the near-UV emissions of these stars, accessible only from space platforms, using optical proxies from the ground.