Rocky, Earth-like Planets Not Rare in Milky Way

Using NASA's Spitzer Space Telescope, a team of scientists found that at least 20 percent, and possibly the majority (as many as 60 percent) of stars similar to the sun are candidates for forming rocky planets. The Legacy Science Program set out to determine whether planetary systems like ours are common or rare in the Milky Way. What they found is that many, perhaps even most, of the sun-like stars in our galaxy could well harbor Earth-like planets.

The Spitzer team found that at least 1 in 5 neighboring solar-mass stars have the right conditions to have formed terrestrial worlds. This new research indicates that worlds with potential for life may be relatively common.

The research appears in Astrophysical Journal Letters, and the findings were also presented at the annual meeting of the American Association for the Advancement of Science. The research team included University of Arizona astronomer Michael Meyer and colleagues John Carpenter of the California Institute of Technology, Eric Mamajek of the Harvard-Smithsonian Center for Astrophysics and as well as other astronomers from the United States and Germany.

"Theoretical models and meteoritic data suggest that Earth formed over 10-to-50 million years ago from collisions between smaller bodies," says Meyer.

The astronomers began the study by surveying groups of stars with masses comparable to our sun. The stars were then grouped by age, ranging from three-to-10 million years up to one-to-three billion years old. The Sun is about 4.6 billion years old.

"We wanted to study the evolution of the gas and dust around stars similar to the sun and compare the results with what we think the solar system looked like at earlier stages during its evolution," Meyer said.

With the Spitzer telescope, the team detected dust at a range of infrared wavelengths. The hottest dust is found at temperatures more than 2,000 degrees Fahrenheit and is detected at the shortest wavelengths, between 3.6 microns and 8 microns. Cool dust at 380 degrees Fahrenheit, and is detected at the longest wavelengths, between 70 microns and 160 microns. Warm dust, between minus 280 and 80 degrees Fahrenheit is traced at 24-micron wavelengths.

Since dust closest to a star is hotter than dust farther from the star, the warm dust likely traces material orbiting the star at distances comparable to the distances found between Earth and Jupiter and the Sun.

"We found that about 10 to 20 percent of the stars in each of the four youngest age groups shows 24 micron emission due to dust," Meyer said. "But we don't often see warm-dust around stars older than 300 million years. The frequency just drops off. That's comparable to the time scales thought to span the formation and dynamical evolution of our own solar system.”

Other recent studies have collaborated these findings that Earth-like planets could be quite common, hence extraterrestrial life could be relatively common as well.

Scientists are hoping that the next generation of powerful telescopes such as the Giant Magellan Telescope, known as the GMT, which is slated for completion in 2016 in northern Chile, will further shed light on the question.

UA astronomer Phil Hinz points out that "Imaging and spectroscopically characterizing an Earth-like planet is an incredibly difficult task. But if Earth-like planets really are this common, we might just be able to take the first picture of another Earth with the GMT. It's an exciting prospect!"

Posted by Rebecca Sato

Are the Pleiades Harboring Earthlike Planets?

Rocky terrestrial planets, perhaps like Earth, or Venus, appear to be forming or to have recently formed around a star in the Pleiades star cluster, ...

"There are not only more potentially habitable planets, but MANY ...

"It might not be a coincidence that Earth is the largest rocky planet in our solar system, and also the only one with life," said Valencia.

Harvard-Smithsonian Scientists Zero In On Key Sign of Habitable ...
According to Harvard scientists, habitable worlds are most likely found on large, rocky planets that are up to ten times the size of Earth and contain plate ...

A Life Bearing Exoplanet - The Next Great "Page-One" Discovery in…

Stars A and B have been selected as two of the top 100 target stars for NASA's Terrestrial Planet Finder (illustration above) to image small rocky planets ...

Mystery of Mercury: The Shrinking Planet

Earth and Mercury are the only two ROCKY planets in the Solar System to have a magnetosphere. Jupiter, Saturn, Uranus and Neptune also have this feature, ...

NASA's Search for Planet Vulcan -Beyond the Physics of Star Trek ...

Using two separated mirrors and combining their light with a technique known as interferometry, space telescope will able to detect rocky planets as small ...

"Alien Sunsets" -NASA's Search for Binary Stars & Earthlike…

These so-called debris disks are made up of asteroid-like bits of leftover rock that never made it into rocky planets like Earth. ...

Source:
http://uanews.org/node/18321
http://www.spitzer.caltech.edu/spitzer/index.shtml