Searching for planets in clouds of dust

Feb 10, 2012 By Celeste Barajas
If selected for flight, EXCEDE will use a 2.3 foot (.7 meter) primary mirror and a sophisticated starlight suppression system that will enable astronomers to observe the regions around stars otherwise hidden by starlight. Credit: Glenn Schneider/Steward Observatory

( -- A UA astronomy research team was awarded a $600,000 grant for technology development under NASA’s Explorer mission program. The mission would send a space telescope high above Earth's surface to watch how planets around other stars form and evolve.


At the University of Arizona's Steward Observatory, an team is asking questions such as, "How do planets like those found by Kepler arise? What materials are present during their initial formation? How do they evolve?"



If selected for flight, EXCEDE would orbit 2,000 kilometers above the Earth's surface. It would use a primary mirror 2.3 feet (.7 meter) wide and a highly efficient starlight suppression system that would allow astronomers to see past a star's glare to observe the surrounding regions where possible planets may abide.  



Searching for planets in clouds of dust
The dust disks around stars provide clues as to what types of materials help form planets and how they evolve. Credit: Glenn Schneider/Steward Observatory



This is a theoretical model depicting planets shaping the dust around stars, forming "gaps" or streaks with their orbits. EXCEDE will study the structures within the dust around stars to identify existing planets. Credit: Glenn Schneider/Steward Observatory


"With their gravity, those planets shape the dust around stars, leaving dust structures for us to see and deduce the planet orbits," said Schneider. "We're interested in the entire circumstellar regions where planets might exist, but the uniqueness space is the region we call the habitable zone – where, in principle, water-based life could exist."

While other types of coronagraphs (left), block out only some of a star's glare, the PIAA coronagraph (right) will suppress all of the light from a star, rendering the surrounding dust disks more visible. Credit: Glenn Schneider/Steward Observatory

To image the dusty regions surrounding stars, EXCEDE will use a sophisticated device called the Phase Induced Amplitude Apodized Coronagraph, or the PIAA coronagraph, pioneered by EXCEDE's instrument scientist Olivier Guyon.




"The PIAA coronagraph instead consists of highly curved mirrors to remap all of the light so there is no loss of light," explained Schneider. "It puts the light where it's supposed to be, if nature didn't diffract it in the first place. We need something new, and that's what EXCEDE is designed to do."


"Beyond EXCEDE, the big push is to find out how common  Earth-like planets are and how unique or non-unique is the Earth itself," Schneider added. "In the long-range look of things, we want to find Earth-like around and characterize them. A part of this is the search for life outside of our solar system."


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not rated yet Feb 10, 2012
Kepler has found more than 2,326 possible Earth-like planets?!?! Did I miss this news somewhere or is this an incorrect statement?
not rated yet Feb 11, 2012

No, that sentence in the article is technically wrong. Close though. Kepler has found that many planets in total, including gas giants which make up the bulk of its findings, and actually it has found none that scientists have been able to confirm as being truly "Earth-like", meaning an exoplanet of similar size, mass, orbit and atmosphere orbiting a star similar to the sun. To date, it has found a small number of 'super-Earths', maybe a dozen or so, which have anywhere from 4-10 Earth masses, and it also has found a very small number of small rocky worlds with comparable mass to the Earth.

However, the vast majority of these planets have orbits that make them completely different than Earth, usually orbiting their parent stars at a very close distance, far closer even than Mercury to the Sun.


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