Telescopes for Stardust
While a broad spectra of light and radio telescopes exist, a new generation of instruments is being considered for the collection of interstellar samples. As it turns out, an enormous flow of cosmic debris is right under our feet, and some scientists are considering how best to collect it.
Forget the starlight, and don’t dust off your telescope just yet.
For instance, University of Toronto astronomers say that detecting such microscopic meteors from other solar systems could provide clues about the formation of planets like Earth.
Dust streams from our sun’s stellar neighbours consist of tiny grains of pulverized rock ejected from a disk of dust and debris that commonly surrounds young stars, says Joseph Weingartner, a post-doctoral fellow at U of T’s Canadian Institute for Theoretical Astrophysics. According to Professor Norman Murray, associate director of CITA and co-author of the study, "if we can detect these grains and trace them back to the star system that they came from, we’d have very good evidence of planet formation going on in that system."
Weingartner presented the study Jan. 6 at the American Astronomical Society meeting in Seattle, Wash.
|Image of dust clouds give the interstellar medium around the blue nebula, NGC1999, its distinct hue. The dust scatters light and is sometimes referred to as the Reflection Nebula.|
Credit: NASA Hubble
The tiny grains are created by collisions of large objects such as boulders and asteroids during or slightly after the process of planet formation, he explains. The collisions create a disk of particulate grains (each grain is about 100 times smaller than a grain of sand).
Some of these grains are then ejected from a disk after "slingshotting" around a planet. Weingartner says the speeds of the grains entering our solar system can range from a few kilometers to 100 kilometers per second (~200 times the speed of a bullet). If the grains are travelling at high velocities, researchers know that they originate from outside our solar system.
Weingartner and Murray propose that future radar telescope facilities that can examine roughly one million square kilometers of space be used to detect dust streams coming from nearby stars. By detecting the speed and direction of grains when they hit the Earth’s atmosphere, scientists could potentially trace the path of the tiny grains back to star systems where planet formation may be occurring.
"In astronomy, if you want information, you always rely on radiation like visible light or infrared light," says Weingartner. "You can think of these radar facilities as a different type of telescope – a telescope for collecting dust rather than a telescope for collecting light."
Among the star systems whose dust streams could be studied is beta Pictoris, a 10-to-20 million-year-old star located roughly 63 light years from the sun. Weingartner and Murray estimate that in the dust disk around beta Pictoris, the mass of the particles with a radius of one centimeter or smaller is about 19 times the mass of the Moon.
"We have a real opportunity to open a new window on these kinds of systems," says Weingartner. He and Murray say that their study is a first step in a new approach to astronomical research, and note that further studies will require the construction of large radar telescope facilities with expanded sky coverage.
Astronomers expect that future infrared space telescopes will help probe the fascinating stuff between the stars. NASA’s Space Infrared Telescope Facility (SIRTF) is due to launch in July 2002, and the ESA’s Herschel is due to launch in 2007. These space telescopes will penetrate even more deeply into the cold and dark regions where star and planet formation first begins.
Related Web Pages
Canadian Institute for Theoretical Astrophysics Interstellar Medium (background) Cold Clouds and Water in Space
Space Infrared Telescope Facility Science Center (Caltech)
Infrared Camera MIRAC3/BLINC (Harvard)