Earth-like Planet : Gliese 581

8 11 2010

http://www.youtube.com/v/wJXSSYyIVqw?fs=1&hl=en_US&rel=0

Gliese 581 (from "Journey to the Edge of the Universe")

http://www.youtube.com/v/-TBldZ4eNw0?fs=1&hl=en_US&rel=0

http://www.youtube.com/v/PXoW4HERMzw?fs=1&hl=en_US&rel=0

http://www.youtube.com/v/qrSH-g8G1jQ?fs=1&hl=en_US&rel=0

Gliese 581 is a red dwarf star with spectral type M3V, located 20.3 light years away from Earth in the constellation Libra. Its estimated mass is about a third of that of theSun, and it is the 87th closest known star system to the Sun. Observations suggest that the star has at least six planets: Gliese 581 e, b, c, g, d and f. Significantly, planet g is thought to be close to the middle of the star’s habitable zone.

The star system first gained attention after Gliese 581 c, the first low mass extrasolar planet found to be near its star’s habitable zone, was discovered in April 2007. It has since been shown that under known terrestrial planet climate models, Gliese 581 c is likely to have a runaway greenhouse effect, and hence is probably too hot to be habitable, analogous to Venus. A subsequently discovered planet Gliese 581 d, may be just inside or just outside the outer boundary of the habitable zone (depending in part on the greenhouse properties of its atmosphere), analogous to Mars. The discovery of exoplanet Gliese 581 e, at that time the closest-known in mass to Earth, was announced in April 2009. Excitement spiked again in September 2010 with the discovery of Gliese 581 g, orbiting between c and d, believed to be the planet with the greatest likelihood of having conditions suitable for liquid water at its surface found to date.


NASA and NSF-Funded Research Finds First Potentially Habitable Exoplanet

A team of planet hunters from the University of California (UC) Santa Cruz, and the Carnegie Institution of Washington has announced the discovery of a planet with three times the mass of Earth orbiting a nearby star at a distance that places it squarely in the middle of the star’s “habitable zone.”

This discovery was the result of more than a decade of observations using the W. M. Keck Observatory in Hawaii, one of the world’s largest optical telescopes. The research, sponsored by NASA and the National Science Foundation, placed the planet in an area where liquid water could exist on the planet’s surface. If confirmed, this would be the most Earth-like exoplanet yet discovered and the first strong case for a potentially habitable one.

To astronomers, a “potentially habitable” planet is one that could sustain life, not necessarily one where humans would thrive. Habitability depends on many factors, but having liquid water and an atmosphere are among the most important.

The large planet in the foreground is Gliese 581g with nearby red dwarf star Gliese 581. Read more: http://news.nationalpost.com/2010/10/13/more-news-from-newly-discovered-habitable-planet-gliese-581g/#ixzz14cskwBzZ

The new findings are based on 11 years of observations of the nearby red dwarf star Gliese 581using the HIRES spectrometer on the Keck I Telescope. The spectrometer allows precise measurements of a star’s radial velocity (its motion along the line of sight from Earth), which can reveal the presence of planets. The gravitational tug of an orbiting planet causes periodic changes in the radial velocity of the host star. Multiple planets induce complex wobbles in the star’s motion, and astronomers use sophisticated analyses to detect planets and determine their orbits and masses.

“Keck’s long-term observations of the wobble of nearby stars enabled the detection of this multi-planetary system,” said Mario R. Perez, Keck program scientist at NASA Headquarters in Washington. “Keck is once again proving itself an amazing tool for scientific research.”

Steven Vogt, professor of astronomy and astrophysics at UC Santa Cruz, and Paul Butler of the Carnegie Institution lead the Lick-Carnegie Exoplanet Survey. The team’s new findings are reported in a paper published in the Astrophysical Journal and posted online at:

http://arxiv.org
“Our findings offer a very compelling case for a potentially habitable planet,” said Vogt. “The fact that we were able to detect this planet so quickly and so nearby tells us that planets like this must be really common.”

The paper reports the discovery of two new planets around Gliese 581. This brings the total number of known planets around this star to six, the most yet discovered in a planetary system outside of our own. Like our solar system, the planets around Gliese 581 have nearly-circular orbits.

The new planet designated Gliese 581g has a mass three to four times that of Earth and orbits its star in just under 37 days. Its mass indicates that it is probably a rocky planet with a definite surface and enough gravity to hold on to an atmosphere.

Gliese 581, located 20 light years away from Earth in the constellation Libra, has two previously detected planets that lie at the edges of the habitable zone, one on the hot side (planet c) and one on the cold side (planet d). While some astronomers still think planet d may be habitable if it has a thick atmosphere with a strong greenhouse effect to warm it up, others are skeptical. The newly-discovered planet g, however, lies right in the middle of the habitable zone.

The planet is tidally locked to the star, meaning that one side is always facing the star and basking in perpetual daylight, while the side facing away from the star is in perpetual darkness. One effect of this is to stabilize the planet’s surface climates, according to Vogt. The most habitable zone on the planet’s surface would be the line between shadow and light (known as the “terminator”).

Related Links:

› University of California (UC) Santa Cruz
› Carnegie Institution

Advertisements

Actions

Information




%d bloggers like this: