Seth Redfield, assistant professor of astronomy, received a grant worth $65,932 from the Space Telescope Institute to support a project titled, “Cool Star Winds and the Evolution of Exoplanetary Atmospheres.” The grant expires in October 2014.
Redfield is observing stars that are host to their own planetary systems. These “exoplanets” were only discovered in the last decade or so, and since their discovery, astronomers are very interested in learning more about the properties of these planets and their atmospheres.
“Invariably, the study of exoplanets is really an exercise in putting life on Earth into a cosmic context. How common are planets? Are these planets ‘habitable,’ which is just shorthand for, could liquid water exist on this planet? This project seeks to address the important relationship between a planet/atmosphere and its host star,” Redfield explains.
Scientists know that the host star plays a major role planets and their atmospheres, and the diversity of stars in our galaxy is quite extreme. One way that stars influence their planets is through a stellar “wind,” which is composed of charged particles that escape the gravitational field of the Sun and travel out into interplanetary space. When solar wind interacts with the Earth’s magnetic field, it creates aurora borealis.The solar wind might have been so strong when the Sun was young, that it could have effectively sand-blasted an entire planetary atmosphere away, particularly if that planet did not have a strong magnetic field,” Redfield says. This may have happened with Mars, which does not have a strong global magnetic field like Earth does.
This would explain why we see ancient evidence of surface water, which implies Mars had a substantial atmosphere at the time, but today, Mars is arid and has a very minimal atmosphere.
“The observations I plan to do will measure the interaction of stellar winds with the surrounding interstellar gas and dust. This will give us a handle on the strength of the stellar wind, and enable us to explore the impact of these winds on the planets that are currently around these stars,” he says. “These stars are ‘cool’ not only because they are incredibly amazing to study, but because their surface temperatures are on the lower side compared to other stars we observe.”
The Sun is also a cool star.