June 14, 2010
Jeremy Craig, 404-413-1357
Georgia State's Cassy Davison thinks that we'll find life outside of our solar system - even within the next few decades.
Thanks to the National Science Foundation, the astronomy doctoral student has the chance to advance the quest for a discovery that will inspire and enthrall the world, by looking for new planets.
"It will be exciting, not just for scientists, but for the entire world," she said. "The main thing is not just finding life, but recognizing it when you do find it. Would you recognize life if it wasn't carbon-based? If it was intelligent, would you know how to communicate with them?"
Davison was named an NSF Fellow, which will allow her to travel to telescopes in Hawaii and Chile, affording her access to the tools used for the search for new planets - planets which may have the capability to support life.
Specifically, she's looking for planets around stars smaller than the sun, and in close proximity to our solar system - astronomically speaking, since this 10 parsec range extends to about 192 trillion miles from the sun.
Davison is using two methods in the quest for undiscovered planets: astrometry, and velocity measurements. Indirectly, astronomers can infer the existence of an unseen companion through its effects on the star itself.
"If the target star is moving back and forth compared to reference stars that we assume are stationary, it is likely that a planet is there tugging on the star of interest," she said.
With astrometry, which she will perform in Chile, Davison measures the position of the stars and find the exact distance along with their motion across the sky, and then see if there is an additional "wobble," a slight periodic change in the star's position due to the gravitational pull of a planet.
When using velocity measurements, scientists take spectra of a star and take a look at the star's light waves– whether the light waves are "red shifted," indicating a movement away, or "blue shifted," indicating that star is coming toward the astronomer. This is known as the Doppler shift.
If the astronomer can see the star moving periodically both away and toward the viewer, scientists can infer the presence of a planet tugging on a star.
Many astronomers have looked for planets around stars like our sun, an average star considered to be in the middle range in terms of how bright it is and how large it is. But there's a new push to look for planets around low-mass stars and brown dwarfs, she said.
"We're looking to answer the question of how small a star can be and still have one or more planets," Davison said. "Where does that limit cut off? Are there stars with an insufficient amount of mass to possess a circumstellar disk, out of which planets form? But, I am hopeful that we will find planets around the lowest mass stars. We've found planets even around exotic objects like neutron stars and pulsars."
Beyond her research at Georgia State, she's looking to reach out to students to inspire them to pursue science, including children who have a difficult time learning in conventional settings due to learning disabilities.
With the experience of having a brother who is dyslexic and dysgraphic, she hopes to start a camp which will help students realize that they can learn about science.
"It makes things feel a lot harder to learn, and I really want something for children who have a type of disability to be shown that this camp is meant for them, that they can do it," Davison said. "I do not want it be only an astronomy camp, but science in general. It's one of my big lifetime goals."
Her outreach has also extended to the general public. As an undergraduate, she interned at the White House in the Office of Correspondence, which handles any type of mail from the public to people in power like members of Congress, phone calls, official letters or even gifts which are addressed to the president. There, she helped to explain scientific concepts.
Scientists sometimes don't communicate well with the public. But learning how to speak to them is essential - a better informed public will be able to make informed choices, she said.
"I think if you understand the material well, it's easy," Davison said. "You just have to find a common background with somebody, and if you're willing to talk with them enough, you can help relate Astronomy concepts to them. Astronomy is a science that the public is always interested in."