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The hunt for alien Earths won't come to a dust-up

Elizabeth Howell, News Writer
Dec 8, 2014, 17:16 UTC

Sen—In good news for people seeking Earth-like planets around Sun-like stars, a research study has concluded that, on average, there should not be too much dust in the way to block the view. Dust makes it difficult for telescopes to peer through the material to see planets, so this finding makes the search for an Earth 2.0 all the more encouraging.

Imaging planets is still at a young phase—for now, it is huge gas giants close to Earth that are most easily picked up by cameras—but as more sensitive telescopes make it to orbit in the coming decades, the finding is expected to be encouraging news for these telescopic astrophotographers.

According to NASA, researchers are already thinking about how to capture these small-planet portraits. Instrument designs are in the works, and analyses are already going on of dust surrounding a number of stars to see how these particles would interfere with optical systems.


Fomalhaut b, at about 2-3 times the mass of Jupiter, is one of a handful of planets outside of our solar system to be imaged. Image credit: NASA, ESA, P. Kalas, J. Graham, E. Chiang, E. Kite (Univ. California, Berkeley), M. Clampin (NASA/Goddard), M. Fitzgerald (Lawrence Livermore NL), K. Stapelfeldt, J. Krist (NASA/JPL)

"Dust is a double-edged sword when it comes to imaging distant planets," stated Bertrand Mennesson, who led a study at NASA's Jet Propulsion Laboratory. "The presence of dust is a signpost for planets, but too much dust can block our view."

"We want to avoid planets that are buried in dust," he added. "The dust glows in the infrared and reflects starlight in the visible, both of which can outshine the planet's light."

The results come from a survey of almost 50 stars using the W.M. Keck Observatory telescopes that are located in Mauna Kea, Hawaii. The research took place between 2008 and 2011 and used an interferometer that was able to examine the dust for its properties.


An image of Beta Pictoris b taken using the Gemini Planet Imager. Credit: Christian Marois, NRC Canada

The study encompassed examinations of dozens of mature, Sun-like stars to see if they had dust in the "habitable zone"—the area where liquid water is believed to exist, although this can vary greatly with planetary properties such as atmosphere.

Keck was on the hunt for warm dust, about room temperature, to follow on from an earlier study that found about half of the stars examined had no cold dust in spots further away in those star systems. The new research showed that those stars with cold dust will likely also have warm dust, making the entire system difficult to penetrate with optical equipment.

"The outer belt is somehow feeding material into the inner, warm belt," stated co-author Geoff Bryden, who is at JPL. "This transport of material could be accomplished as dust smoothly flows inward, or there could be larger comets thrown directly into the inner system."

The research will be published in the Astrophysical Journal. More examinations of dusty systems are planned using the Large Binocular Telescope Interferometer on Mount Graham in Arizona, to figure out where the dust came from, how much there is and where it is located.