Star alignment may mean finding Earth-like planets in the nearest stellar system

By James Maynard , Jun 04, 2013 12:36 PM EDT

Proxima Centauri is the closest star to the Earth, other than our own Sun, and and over the next three years, a pair of rare stellar alignments will make it possible to search for a planetary system there.

The star is a red dwarf, visible only from the southern hemisphere, that lies 4.2 light years from our home world. Proxima Centauri is a member of a system of three stars that comprise the Alpha Centauri system.

"Proxima Centauri's trajectory offers a most interesting opportunity because of its extremely close passage to the two stars," Kailash Sahu, an astronomer with the Space Science Telescope Institute, said.

Red dwarfs are the most common type of stellar object in the galaxy, making up about 75 percent of known stars. Every one of these long-lived stars ever created is still burning today, and there are ten red dwarfs for every star like our Sun, according to NASA.

In October 2014 and February 2016, Proxima Centauri will pass in front of a pair of other stars. This will create what is known as a microlensing effect. When Proxima Centauri passes in front of each of the background stars, the light from the more-distant object will bend around the foreground star due to gravity. This will make Proxima Centauri act like a lens, producing microlensing. The brightness of light from the background star will change over the course of a few hours to a few days. Measuring these changes will reveal significant information about Proxima Centauri.

These tiny shifts in brightness may also make it possible to detect planets in orbits up to four times the distance from Proxima Centauri as the Earth is from the Sun.

The microlensing effect will be so small, however, that only the most precise observatories, including the Hubble Space Telescope, are nearly-certain to see it. The Gaia space telescope and Chile's Very Large Telescope may be able to observe the phenomenon as well. Under ideal conditions, it may even be possible to detect Earth-sized worlds due to the stellar alignment. One blazing hot alien world, about the same size as the Earth, was found around Alpha Centauri B, another star in the stellar trio.

"If the planet happens to pass close to the star, it's possible to detect," Sahu said.

Researchers will also be able to make precise calculations of the mass and diameter of Proxima Centauri, as well as measure the star's surface temperature with a finer degree of precision than previously available.

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