Gliese 581 exo planet - WAUV - a major step towards a new Earth
In a finding that if confirmed could stand as a landmark in history, astronomers have reported discovering the most Earth-like planet outside our Solar System to date: a world that may have liquid oceans and thus life......
Located only 20.5 light-years away - Gliese 581 is among the 100 closest stars. So close, that we could consider sending a mission towards Gliese within this century!
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Lets recapitulate what this blog is all about: A wager on when we will find the first true exo Earth.
We had talked about this for years before 2002 - but 5 years ago we formalized the bet to: When will we find Earth 2? And this blog was initialized - I.e.:
[The planet we are talking about must not only look like Earth in size and color - we think it must have an atmosphere,
perhaps even a diverse landscape where life can find many different
niche's. In some distant future it should be possible for
humans to settle the place. It short, it should be VERY Earthlike.
Obviously, all other kinds of planets will also be extremely
interesting, but here we are talking about Earth II. ]
It was further understood that the Exo Earth should be within the habitable zone of its star. Gravity should be Earth like - We didn't have to many details on what the atmosphere should be like - but the planet should have an atmosphere - and it should potentially be possible to terraform that atmosphere in order for people to be able to settle the planet. The planet should also have a "home" feeling - i.e. look like Earth- where it almost follows from this that there should be liquid water on the planet (but again, we left if for the the future to settle the exact details).
And we had:
Jan Holst Jensen: - The Kepler Mission will find such a planet more or less immediately after launch. That is in 2007 - 2008.
Simon Laub: Was a little bit more cautious, ..So he is betting on 2012.
The interesting date is the confirmation date. But we are ok with a little wiggle-room for a debate on whether we should instead be talking discovery date. Discovery date is allowed - if the discovery
has all the hallmarks of a confirmation as well.
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Fast forward to April 24th 2007...
Gliese's planet is in the habitable zone of the Star!
The red dwarf Gliese 581, is smaller and colder than the Sun – and thus less luminous – the planet lies in the habitable zone, the region around a star where water could be liquid!
Glies's planets gravity would be twice that of Earth.
Which then makes it open to interpretation, whether that is something humans could settle. But for now it seems ok.
Moreover, the planet around Gliese's radius is estimated to only 1.5 times the Earth’s radius, and models predict that the planet should be either rocky – like our Earth – or covered with oceans,” he said.
Obviously, we need confirmation on all of this. But so far this is very promising.
With water and an atmosphere on Gliesse's Earth like planet - a nice blue feel to it - Jan is the winner of our wager.
Long before the Kepler mission even made it to liftoff...
But we need more details. The wager is not settled yet!
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The Gliese story so far - April 24th 2007:
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In a finding that if confirmed could stand as a landmark in history, astronomers have reported discovering the most Earth-like planet outside our Solar System to date: a world that may have liquid oceans and thus life.
Swiss, French and Portuguese scientists found the body, estimated as 50 percent wider than our Earth, orbiting a so-called red dwarf star relatively close to Earth. The star is thought to harbor two other planets also.
The newfound exoplanet—as astronomers call planets around stars other than the Sun—would be the smallest such body ever reported.
Nonetheless, the object is estimated to weigh as much as five Earths, partly thanks to its greater width. For the same reason, it would have more than twice Earth’s surface area. Historically, only large exoplanets lend themselves to human detection, though that is changing.
Other curious features of the newfound planet are that gravity at its surface would be around twice as strong as on Earth; and its year is just 13 Earth days long, as it completes one orbit about its sun in that time.
It’s 14 times closer to its star than we are from our Sun, researchers said. But since its host star, the red dwarf Gliese 581, is smaller and cooler than the Sun, the planet nevertheless would lie in its habitable zone—the region around a star with suitable temperatures for liquid water.
Average temperatures on this “super-Earth” lie between 0 and 40 degrees Celsius (32 to 104 degrees Fahrenheit), “and water would thus be liquid,” said Stéphane Udry of Switzerland’s Geneva Observatory, lead author of a paper reporting the result. “Models predict that the planet should be either rocky—like our Earth—or covered with oceans,” he added.
Liquid water is critical to life as we know it,” noted Xavier Delfosse, a member of the team from Grenoble University, France.
“Because of its temperature and relative proximity, this planet will most probably be a very important target of the future space missions dedicated to the search for extra-terrestrial life. On the treasure map of the Universe, one would be tempted to mark this planet with an X.”
The host star, Gliese 581, is among the 100 closest stars to us, lying 20.5 light-years away in the constellation Libra (“the Scales.”) A light-year is the distance light travels in a year.
Gliese 581 has one third the mass of our Sun. Such small stars, called red dwarfs, are at least 50 times fainter than the Sun and are believed to be the most common stars in our galaxy. Among the 100 closest stars to the Sun, 80 belong to this class.
“Red dwarfs are ideal targets for the search for such planets because they emit less light, and the habitable zone is thus much closer to them than it is around the Sun,” said Xavier Bonfils, a co-researcher from Lisbon University. Planets near a star are easier to detect because their gravitational pull affects the parent star noticeably, inducing something of a wiggling motion.
Red dwarfs are also expected to live extraordinarily long because they burn fuel slowly. A red dwarf one-third the Sun’s mass, like Gliese 581, would typically shine for some 130 billion years, outliving the Sun by thirteen times. That might relieve at least one source of stress for any inhabitants of a red dwarf system. We on Earth are already halfway through the Sun’s lifetime, though much time remains.
Two years ago, Udry and his team found another planet around Gliese 581, estimated to weigh as much as 15 Earths—about as much as Neptune—and orbiting the star in 5.4 days.
At the time, the astronomers had already noted hints of another planet, Udry and colleagues said. They thus took new measurements and found the new “super-Earth,” as well as a likely third planet weighing eight Earths and orbiting in 84 days. The findings have been submitted to the research journal Astronomy and Astrophysics, the scientists said.
The find was possible thanks to an instrument known as a spectrograph on the European Southern Observatory’s 3.6-meter telescope at La Silla, Chile, according to the group. The instrument, called the High Accuracy Radial Velocity for Planetary Searcher, is touted as one of the most successful tools for detecting exoplanets to date.
The instrument measured wiggles in the star’s motion corresponding to velocity changes of just two to three meters per second—the speed of a brisk walk, according to the Geneva Observatory’s Michel Mayor, principal investigator for the instrument. Given the results so far, “Earth-mass planets around red dwarfs are within reach” of discovery, he predicted.
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An international team of astronomers from Switzerland, France and Portugal have discovered the most Earth-like planet outside our Solar System to date.
The planet has a radius only 50 percent larger than Earth and is very likely to contain liquid water on its surface.
The research team used the European Southern Observatory’s (ESO’s) 3.6-m telescope to discover the super-Earth, which has a mass about five times that of the Earth and orbits a red dwarf already known to harbour a Neptune-mass planet.
Astronomers believe there is a strong possibility in the presence of a third planet with a mass about eight times that of the Earth in the system.
However, unlike our Earth, this planet takes only 13 days to complete one orbit round its star. It is also 14 times closer to its star than the Earth is from the Sun.
However, since its host star, the red dwarf Gliese 581, is smaller and colder than the Sun – and thus less luminous – the planet lies in the habitable zone, the region around a star where water could be liquid!
“We have estimated that the mean temperature of this super-Earth lies between 0 and 40 degrees Celsius, and water would thus be liquid,” said Stéphane Udry from the Geneva Observatory, Switzerland and lead-author of the paper in the journal Astronomy and Astrophysics.
“Moreover, its radius should be only 1.5 times the Earth’s radius, and models predict that the planet should be either rocky – like our Earth – or covered with oceans,” he said.
“Liquid water is critical to life as we know it and because of its temperature and relative proximity, this planet will most probably be a very important target of the future space missions dedicated to the search for extra-terrestrial life. On the treasure map of the Universe, one would be tempted to mark this planet with an X,” added Xavier Delfosse, a member of the team from Grenoble University, France.
According to the research team, the host star, Gliese 581, is among the 100 closest stars to us, located only 20.5 light-years away in the constellation Libra (“the Scales”).
The star has a mass only one third that of the Sun. Such red dwarfs are at least 50 times intrinsically fainter than the Sun and are the most common stars in our Galaxy. Among the 100 closest stars to the Sun, 80 belong to this class.
“Red dwarfs are ideal targets for the search for such planets because they emit less light, and the habitable zone is thus much closer to them than it is around the Sun. Any planets that lie in this zone are more easily detected with the radial-velocity method, the most successful in detecting exoplanets,” said Xavier Bonfils, a co-worker from Lisbon University.
Labels: a new Earth, exo Earth, Gliese 581
posted by Simon, Lars and Erik @ 11:45 AM
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