Proto-Earths May Be Abundant

by Paul Gilster on November 26, 2004

New infrared studies of the dust around three young stars lend credence to the idea that Earth-like planets may circle other stars. Using the European Southern Observatory’s Very Large Telescope Interferometer (VLTI), a team of astronomers studied the proto-planetary disks around the stars, homing in on the inner region of the discs. The results: the inner discs, in the area analogous to that swept out by the Earth around the Sun, are loaded with crystalline silicate grains — sand — with an average diameter of about 0.001 mm. Much smaller grains (about 0.0001 mm in size) would have contributed to the creation of this material, being heated in the inner system near the young star and coagulating into larger grains in this dense region.

From an ESO press release:

An important conclusion from the VLTI observations is therefore that the building blocks for Earth-like planets are present in circumstellar discs from the very start. This is of great importance as it indicates that planets of the terrestrial (rocky) type like the Earth are most probably quite common in planetary systems, also outside the solar system.

Says Dutch astronomer Rens Waters:

“With all the ingredients in place and the formation of larger grains from dust already started, the formation of bigger and bigger chunks of stone and, finally, Earth-like planets from these discs is almost unavoidable!”

Interferometry — combining the light from multiple telescopes — allows VLTI to offer a hundred-fold increase in angular resolution over previous studies, rendering the infrared spectra around the stars HD 144432, HD 163296 and HD 142527 in unprecedented detail. The VLTI is an array of four 8.2-meter telescopes (the VLT itself) that are being supplemented with four movable 1.8-meter auxiliary telescopes that can be moved along a grid of railroad tracks. The team used two of the 8.2-meter telescopes a hundred meters apart for its observations. The entire array is installed at the Paranal Observatory in Chile’s Atacama Desert.

The team’s results appear in more detail in Roy van Boekel et al., “The building blocks of planets within the ‘terrestrial’ region of protoplanetary disks” (Nature, November 25, 2004). Image credit (above): European Southern Observatory.

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