From RedOrbit and Science News Astronomers Discover Lightest Exoplanet Yet
Astronomers claim to have discovered an exoplanet that is the most similar to Earth in terms of mass than any previously discovered.
Found in the constellation Libra, the planet known as Gliese 581 represents about twice the mass of Earth.
Astronomers have previously identified some 300 exoplanets, but most are much larger than Earth.
“This is by far the smallest planet that’s ever been detected,” said Michael Mayor, from the Geneva Observatory, Switzerland.
“This is just one more step in the search for the twin of the Earth.
“At the beginning, we discovered Jupiter-like planets several hundred times the mass of the Earth; and now we have the sensitivity with new instruments to detect very small planets very close to that of the Earth,” he told BBC News.
Mayor worked alongside an international team of scientists who made the observation using the low-mass-exoplanet hunting device known as the HARPS spectrograph, which is attached to the 3.6 meter ESO telescope at La Silla, Chile.
“The holy grail of current exoplanet research is the detection of a rocky, Earth-like planet in the ‘habitable zone’ – a region around the host star with the right conditions for water to be liquid on a planet’s surface,” Mayor said in a statement.
“With only 1.9 Earth-masses, it is the least massive exoplanet ever detected and is, very likely, a rocky planet”, said co-author Xavier Bonfils from Grenoble Observatory.
Although the planet passes too close to its star for life to be possible, scientists claim that another planet in the system may be.
Previous observations using the HARPS showed that the host star was known to harbor a system with a Neptune-sized planet and two “super-Earths”.
Gliese 581 d was discovered two years ago with a mass of about seven times that of Earth. It orbits its parent star in 66.8 days, according to astronomers.
“Gliese 581 d is probably too massive to be made only of rocky material, but we can speculate that it is an icy planet that has migrated closer to the star,” said team member Stephane Udry.
“‘d’ could even be covered by a large and deep ocean – it is the first serious ‘water world’ candidate,” she added.
Sophisticated modern technology allows astronomers to observe exoplanets by studying the tiny wobble in star motion. The discovery of low-mass red dwarf stars like Gliese 581 adds potential of finding other low-mass exoplanets in the habitable zones, scientists said.
“With similar observing conditions an Earth-like planet located in the middle of the habitable zone of a red dwarf star could be detectable,” said Bonfils. “The hunt continues.”
“It is amazing to see how far we have come since we discovered the first exoplanet around a normal star in 1995 – the one around 51 Pegasi,” says Mayor. “The mass of Gliese 581 e is 80 times less than that of 51 Pegasi b. This is tremendous progress in just 14 years.”
The international team’s findings will be published in the journal Astronomy & Astrophysics.
From Science News:
“The object, a mere 20.5 light-years away, could be as tiny as 1.9 Earths and isn’t likely to exceed twice that amount.”
This diagram shows the position of the four planets in the Gliese 581 system. The newly found, innermost body is Gliese 581 e, the smallest exoplanet yet discovered. The habitable zone (blue region), where water could exist as a liquid, clearly includes the outermost planet, Gliese 581 d.
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can humans survive in an environment with twice the g’s found on earth?
Does the headline need revision?
“Although the planet passes too close to its star for life to be possible, scientists claim that another planet in the system may be.”
I’d say it isn’t nearly as important that we found the possibility of life at Gliese 581as it is the possibility that they have found us… 8^)
Umm… don’t you mean Gliese 581-c?
Now all they need do is to see if they can find intelligent life on the third planet from our nearest star.
Only 20 light years?
Well, as soon as we defeat the laws of physics and create a faster than light space shuttle, maybe we can make the round trip in a decade or two?
A mass 7 times that of Earth. A nice bit of gravity on that baby then. I bet it attracts a few more extinction level asteroids than the Earth does.
AKD-
I also found the title rather misleading. Still, a remarkable find!
Stef-
During which time the earth will have aged significantly more than that, relativistically. Space travel is certainly much harder than used to be generally believed. Remember “Space 1999”?
If they start finding habitable planets harboring civilized space-faring life like crazy then how long before it goes like in Star Wars and we see a Galactic Senate, or what if the galaxy already has a president named Beeblebrox?
Even though no life is found yet, what about the water world? Would be nice to draw it through a portal to irrigate and green up the deserts on Earth (if it ever becomes possible)?
This is really exciting.
In related news… The president has asked NASA to immediately dispatch a message to any space aliens who may be living on that planet.
Hey all you great individuals on the newly discovered planet,
First, I, as the President of one of the family of nations of Planet Earth, would like to go ahead and apologize to your entire population for anything we may have done to have offended you, like perhaps reruns of Gilligan’s Island. Also I would like to let you know that if you find yourselves here in America, be assured that you are entitled to the best education that unions can supply, AND food stamps and welfare. Do not ever worry that you may be putting us out, we have plenty of money and we are currently printing it as fast as we can.
Welcome to America!!
Don’t forget to vote!!!
Is there a vertical scale to the diagram?
Astronomer Guillermo Gonzalez developed the “Galactic Habitable Zone” theory.
e.g. see: Amid the Universe’s Chaos, a Few Habitable Places
Gonzalez describes this Galactic Habitable Zone in Chapter 8 of The Privileged Planet: How Our Place in the Cosmos Is Designed For Discovery Gonzalez, Guillermo and Richards, Jay W. 2004 Regnery Pub. ISBN 0895260654.
Preview at Google Books
Gonzalez is co-author of the text: Observational astronomy
Mike B.,
We have nothing to worry about: click
As long as they get to see every episode of Single Female Lawyer, we should be OK. Wait, no, can’t happen since that hasn’t been 20 years yet. Maybe they’re watching something else.
Mark
PS: a Futurama joke.
Clearly the Habitable zone must assume a certain % of Carbon Dioxide, because as we all know, plants must have a very precise CO2 content to be habitable.
CO2 content ??????
Ah, hope springs eternal for a race of aliens we can meet, trade with, go to war against and perhaps go to bed with too. Every scientist’s holy grail? Every science-fiction geek’s holy grail then as well.
Send Al gore. After listening to him bloviating for five minutes there’s no way the inhabitants will ever think it worthwhile to warp over here and conquer what’s left of our little pile of smouldering ash.
Looking at the diagram, earth would be in the blue zone directly above the 1.0 AU mark, high on the chart. To have a habitable zone 0.1 AU away, the star would have to be about as bright (color temperature) as a low wattage incandescent light bulb. A Gliesian in the zone would have a dimmer sun that would still feel as warm on the skin (or scales) as our sun does.
It would be a very happy place, because Christmas would come every other month.
Someday, an expedition from Gliese 581will come to Earth. They will find no intelligent life but they will find evidence of our existence in the ruins of our cities. After a time they will decode the various languages on the signs that outlawed CO2 and wonder how we could have ever been so stupid. They will see plant life returning and pushing up through the concrete and asphalt, breaking it up into smaller and smaller pieces. The alien scientists will enter us into their equivalent of what we knew as the “Darwin Awards” and then make plans for colonization of the planet.
Wait a minute. Al Gore, James Hansen et al are probably the first wave of a plan hatched on Gliese 581to get us all to suffocate ourselves. There still may be time… 8^)
Would a planet of 1.9 Earth masses have doubled gravity? Is gravity that linear? I would think it would depend on the composition too.
“and now we have the sensitivity with new instruments…”
This was the subject of a graduate seminar I attended in 1976. The speaker was clearly frustrated by the lack of state of the art sensing devices available to the scientist. And the lack of a comprehensive effort to create better sensors.
His comment was something on the order of ‘ If scientists today could have the sensors that should have been available (ie. state-of-the-art) at the time, the advancement of science would have been a full ten years beyond what it was currently . But since very little efforts were being made to advance sensor technology…they were currently ten years behind. ‘
I believe his comments were right on the mark. Advancement in sensor technology has worked wonders in some cases…like the extended capabilities of the Hubble telescope. But it has made life miserable for others…like pollutant control. I remember when PCB limits were controlled down to ~1ppm in the early 70’s because that was about the limit of convenient detection. By the early 90’s that limit had dropped to ~10ppb. the science at the time did not confirm that the danger levels were just as significant at a level of 100 times lower, but the new instrumentation/detection methods were that much better. Today those levels are approaching 10ppt and there is some talk about lowering the allowable limits of PPB levels even lower…
Jim
“can humans survive in an environment with twice the g’s found on earth?”
Only the skinny ones…
What is this nonsense about wanting to find liquid water ? Don’t they know that to be habitable, planets need solid ice, and no carbon dioxide; liquid water is the last thing you would want on a habitable planet.
Somebody should tell NASA to update the data on this planet, and bring it more into line with computer simulations of what life is like.
George
Jeff Alberts (13:11:10) :
Would a planet of 1.9 Earth masses have doubled gravity? Is gravity that linear? I would think it would depend on the composition too.
With a larger planet, you have more mass, but someone on the surface is farther away from the additional mass, so probably not doubled.
It would indeed depend on density, but here again, Earth with its iron core is a dense planet so that argues against double gravity.