New super-earth detected within the habitable zone of a nearby star

Feb 02, 2012
An artistic conception of the two planets reported on in this paper: b and c. Planet c is the one that lies in the habitable zone of the star. Planet b is too hot to be habitable. Images courtesy of Guillem Anglada-Escudé

(PhysOrg.com) -- An international team of scientists has discovered a potentially habitable super-Earth orbiting a nearby star. With an orbital period of about 28 days and a minimum mass 4.5 times that of the Earth, the planet orbits within the star’s “habitable zone,” where temperatures are neither too hot nor too cold for liquid water to exist on the planet’s surface. The researchers found evidence of at least one and possibly two or three additional planets orbiting the star, which is about 22 light-years from Earth.

The team includes UC Santa Cruz astronomers Steven Vogt and Eugenio Rivera and was led by Guillem Anglada-Escudé and Paul Butler of the Carnegie Institution for Science. Their work will be published by Astrophysical Journal Letters, and the manuscript will be posted online at arxiv.org/archive/astro-ph .

The host star is a member of a triple-star system and has a different makeup than our Sun, with a much lower abundance of elements heavier than helium, such as iron, carbon, and silicon. This discovery indicates that potentially habitable can occur in a greater variety of environments than previously believed.

The researchers used public data from the European Southern Observatory and analyzed it with a novel data-analysis method. They also incorporated new measurements from the W. M. Keck Observatory’s High Resolution Echelle Spectrograph and the new Carnegie Planet Finder Spectrograph at the Magellan II Telescope. Their planet-finding technique involved measuring the small wobbles in a star’s motion caused by the gravitational tug of a planet.

The GJ 667C triple system as seen from a telescope. Credit: Guillem Anglada-Escude

The host star, called GJ 667C, is an M-class dwarf star. The other two in the triple-star system (GJ 667AB) are a pair of orange K dwarfs, with a concentration of heavy elements only 25 percent that of our Sun’s. Such elements are the building blocks of terrestrial planets, so it was thought to be less likely for metal-depleted star systems to have an abundance of low-mass planets.

“This was expected to be a rather unlikely star to host planets. Yet there they are, around a very nearby, metal-poor example of the most common type of star in our galaxy,” said Vogt, a professor of astronomy and astrophysics at UCSC. “The detection of this planet, this nearby and this soon, implies that our galaxy must be teeming with billions of potentially habitable rocky planets.”

GJ 667C had previously been observed to have a super-Earth (GJ 667Cb) with a period of 7.2 days, although this finding was never published. This planet orbits so close to the star that it would be too hot for liquid water. The new study started with the aim of obtaining the orbital parameters of this super-Earth.

But in addition to this first candidate, the research team found the clear signal of a new planet (GJ 667Cc) with an orbital period of 28.15 days and a minimum mass of 4.5 times that of Earth. The new planet receives 90 percent of the light that Earth receives. However, because most of its incoming light is in the infrared, a higher percentage of this incoming energy should be absorbed by the planet. When both these effects are taken into account, the planet is expected to absorb about the same amount of energy from its star that the Earth absorbs from the Sun.

“This planet is the new best candidate to support and, perhaps, life as we know it,” Anglada-Escudé said.

The team found that the system might also contain a gas-giant planet and an additional super-Earth with an of 75 days. However, further observations are needed to confirm these two possibilities.

“With the advent of a new generation of instruments, researchers will be able to survey many M dwarf stars for similar planets and eventually look for spectroscopic signatures of life in one of these worlds,” said Anglada-Escudé, who was with Carnegie when he conducted the research, but has since moved on to the University of Gottingen.

In addition to Anglada-Escudé, Butler, Vogt, and Rivera, the coauthors include Jeffrey Crane, Stephen Shectman, and Ian Thompson at Carnegie; Pamela Arriagada and Dante Minniti of Pontificia Universidad Catolica de Chile; Nader Haghighipour of the University of Hawaii-Monoa; Brad Carter of University of Southern Queensland; C. G. Tinney, Robert Wittenmyer, and Jeremy Bailey of the University of New South Wales; Simon J. O’Toole of the Australian Astronomical Observatory; Hugh Jones of the University of Hertfordshire; and James Jenkins of the Universidad de Chile, Camino El Observatorio.

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kevinrtrs
1.3 / 5 (31) Feb 02, 2012
This planet is the new best candidate to support liquid water and, perhaps, life as we know it, Anglada-Escudé said.

A very cautious statement indeed considering all the attending problems. Radiation in a 3-star system will be a problem. Gravitational forces for a planet 4.5 times that of earth will be a problem for life similar to earth. The stability of the stars outputs will likely also be a problem.
Hence of course the cautious statement above.
SleepTech
5 / 5 (15) Feb 02, 2012
Only 22 light years from Earth? They ought give this system a better name because I've a feeling we'll be hearing about it for a long time.
kevinrtrs
Feb 02, 2012
This comment has been removed by a moderator.
rubberman
4.4 / 5 (14) Feb 02, 2012
The radiation wouldn't be an issue, GJ667c is at least 56 AU away from the other two stars (or up to 200 according to WIKI), and they are all dwarfs with a fraction of the energy output of our sun.. It would be that the nature of the star this planet is orbiting would only allow a tiny fraction of visible light to reach the surface compared to what we get. However...liquid water is a start!
Xbw
1.9 / 5 (14) Feb 02, 2012
Only 22 light years from Earth? They ought give this system a better name because I've a feeling we'll be hearing about it for a long time.

Agreed. I vote it should be named Vulcan.

Can one of you numbers folks tell me at 4.5 times the mass of Earth, what would the gravity be like?
GreyLensman
5 / 5 (7) Feb 02, 2012
Gravitional forces aren't a problem for aquatic life - at least near to the surface.
jamesrm
5 / 5 (9) Feb 02, 2012
"Gravitational forces for a planet 4.5 times that of earth will be a problem for life similar to earth."

Depends on the planets density and how far the surface is from the centre of mass.
Waterdog
5 / 5 (2) Feb 02, 2012
How likely is that this planet is tidally locked with a year of only 28 days?
Sonhouse
4.2 / 5 (5) Feb 02, 2012
Only 22 light years from Earth? They ought give this system a better name because I've a feeling we'll be hearing about it for a long time.

Agreed. I vote it should be named Vulcan.

Can one of you numbers folks tell me at 4.5 times the mass of Earth, what would the gravity be like?

I assume you mean surface gravity. That depends on the density and radius of the planet, which we have no way of measuring at this time. A guess would be we need a telescope with about a million times the resolution of the Hubble to figure that out, we need a photo to see what the radius is, does it have an atmosphere, et cetera. If it were a rocky core planet the same radius as Earth, it would be 4.5 g or about 44 meters per second^2 but that is unlikely. If it were sufficiently large and lower density internally it could have around the same surface gravity as Earth, also unlikely. My guess is 1.5 to 2 times Earth surface gravity, which would be a pain in the ass to launch rockets!
Sonhouse
5 / 5 (4) Feb 02, 2012
It could be the escape velocity could be anywhere from Earth's 40,000 km/hr to 160,000 km/hr. We could land but it could be very difficult to take off! Say it was 100,000 Km/hr escape velocity, we could only launch rather small payloads and we would have to use higher g forces, maybe 5 g's on the passengers and cargo up from our present 3 or so from Earthy rockets. It goes without saying that if we were to send a probe there it would be unmanned and unlikely to land for the first few probes anyway, even given some future near c velocity propulsion systems. If we could manage 0.5c it would still take 44 years just to get there and 22 years for data to wend its way back to Earth, so 66 years minimum would go by on Earth before you even knew if the probe worked.
Xbw
1.5 / 5 (13) Feb 02, 2012
If we could manage 0.5c it would still take 44 years just to get there and 22 years for data to wend its way back to Earth, so 66 years minimum would go by on Earth before you even knew if the probe worked.


And if I remember my relativity correctly, time would pass differently for anything traveling at that speed.
Sonhouse
5 / 5 (3) Feb 02, 2012
If we could manage 0.5c it would still take 44 years just to get there and 22 years for data to wend its way back to Earth, so 66 years minimum would go by on Earth before you even knew if the probe worked.


It doesn't matter to us on Earth how close to c the probe achieves, from our POV it still takes whatever velocity is has as if it were still on Newton time. Besides, at 0.5c there wouldn't be much to write home about as far as shipboard time goes either. You don't get serious help relativity wise till you get to something like 0.8c or 0.9c. Whatever onboard time is like, our POV shows it still takes whatever speed it is at, so even if it were clocking along at 0.999c from our POV it would still take about 22 years to get there, even if it were only a couple of months for onboard clocks.

And if I remember my relativity correctly, time would pass differently for anything traveling at that speed.

BikeToAustralia
1.4 / 5 (7) Feb 02, 2012
22 light years away; what purpose to knowing that NOW considering how long it would take humanity to reach that planet? Charles Stross, author wrote about some of the challenges (historical precedence) we face with long term planning in his blog "Designing society for posterity".

Regardless, I humbly suggest we work on the means for permanent/ longterm survival in space between Earth and The Moon first. Hollow out an asteroid and use the insides for building materials. Install an airtight liner on the hollowed out insides. Jonah had a whale.

But first, get industry out into space - presently we have only a few explorers of the edge, and on a very tight budget at that.
Sonhouse
5 / 5 (2) Feb 02, 2012
Sorry, was answering Xbw's statement about relativity but put my answer on top of his question.
aroc91
5 / 5 (12) Feb 02, 2012
This planet is the new best candidate to support liquid water and, perhaps, life as we know it, Anglada-Escudé said.

A very cautious statement indeed considering all the attending problems. Radiation in a 3-star system will be a problem. Gravitational forces for a planet 4.5 times that of earth will be a problem for life similar to earth. The stability of the stars outputs will likely also be a problem.
Hence of course the cautious statement above.


Bacteria can grow in centrifuges under thousands of times Earth's gravity. Not a problem.
krundoloss
3.2 / 5 (6) Feb 02, 2012
I think this is just fantastic! Another star system with planets only 22 light years away! If we can figure out a way to send probes with Ion Propulsion in that direction, maybe we can get there in 100 years or so. Honestly I dont see us doing too much space travelling for a while, we are getting more exploration done be just building better telescopes and planet detection methods. Maybe in 100 years, we will get outside this solar system with Manned Flights, but it will take some new tech to make it happen. If we could just learn to do resonant frequency travel - vibrate in the same way as your destination and you will instantly be there - something I saw on TV, they were talking about a captured alien spacecraft.
Xbw
1.8 / 5 (14) Feb 02, 2012
@Krundoloss - Resonant Frequency Travel is all theory at this point. If such a thing even is possible, we are many many years from it. Personally, I think it is more science fiction but who knows. Part of advancing science is questioning the status quo.

Here is an article somewhat related to that type of propulsion http://www.scribd...-To-Work
Sonhouse
4.4 / 5 (7) Feb 02, 2012
22 light years away; what purpose to knowing that NOW considering how long it would take humanity to reach that planet? Charles Stross, author wrote about some of the challenges (historical precedence) we face with long term planning in his blog "Designing society for posterity".

Regardless, I humbly suggest we work on the means for permanent/ longterm survival in space between Earth and The Moon first. Hollow out an asteroid and use the insides for building materials. Install an airtight liner on the hollowed out insides. Jonah had a whale.

But first, get industry out into space - presently we have only a few explorers of the edge, and on a very tight budget at that.

You seem to forget that science advances and lately at an exponential rate. In 50 years we may have a different answer to those kind of questions, of course not too many of us will be alive then so it doesn't really effect us but 100 from now we might have return samples from that planet. Bit early to poo poo.
javjav
4.5 / 5 (2) Feb 02, 2012
If we could manage 0.5c it would still take 44 years just to get there


And if I remember my relativity correctly, time would pass differently for anything traveling at that speed.


You have two missconceptions related with exponential factors:

Time differences due to the relativistic effect are only significant beyond 0,9 c (this relation is an exponential function). Accelerating to 0.5c speed will not change the time perception between both observers (it exists but it would be negligible)

Another exponential miss-conception is regarding gravity. A planet with 5 earth masses and a radius 5 times bigger would experience less gravity force on the surface ( G decreases exponentially with the distance to the center of mass ).

Regarding the rocket, it would easier to build a huge telescope to see the planet than a 0.5 c spaceship. The telescope concept is already possible (although extremely expensive), but a 0.5 c spaceship is not possible with our current technology
baudrunner
1.6 / 5 (5) Feb 02, 2012
I'm glad somebody is doing something with all those graduates.
Burnerjack
1.2 / 5 (5) Feb 02, 2012
As far as surface gravity goes, wouldn't centripetal force from rotation offset the initial force? One other point to note: if one were to achieve 0.5c, how would collision avoidance be carried out? One, even baseball sized celestial jaywalker would do catastrophic damage to any craft light enough to allow such acceleration in the first place.
Deesky
4.5 / 5 (8) Feb 02, 2012
One, even baseball sized celestial jaywalker would do catastrophic damage to any craft

Baseball? How about a speck of dust. :)
Tausch
3 / 5 (8) Feb 02, 2012
Next up:
The exception becomes the rule;
Stars with planets.

The rule becomes the exception;
Stars without planets.

Proxima Centauri. Without planets? And the closest to us?
With every passing day becoming more unlikely.
_nigmatic10
4 / 5 (2) Feb 02, 2012
with an orbital duration of 28 days, that planet is blazing around that star. What impact, if any , would that have on an electromagnetic sphere of our earths strength and would there be an atmosphere at that speed or would it have been stripped away?
Smashin_Z_1885
2 / 5 (5) Feb 03, 2012
Yeah, it would be great to eventually travel there, or send probes. But KEEP IN MIND that a LOT of assumptions are made in calculating and theorizing what such a planet may actually be like, at such an incredible distance from here. 22 light years is a long way; consider that Mars is just a few light minutes away from us ( /- 3 light minutes at it's closet point), and while it's now possible to accurately analyze Mars from equipment on Earth, you must understand that 22 light years to that other planet is distant by a multiple of 3.85 million.
Tidal forces between solar systems has yet to be understood, and will never be understood until spacecraft are able to enter interstellar space with sensitive equipment to measure such forces. A new set of calculations will have to be developed to navigate interstellar space in such a case. Then, a full understanding of the gravitational forces within the 'new' solar system being explored must be acquired, if any space craft is to successfull
ROBTHEGOB
1.4 / 5 (9) Feb 03, 2012
Our immediate future is here in this solar system; let us not waste time trying to get to other stars, at least until we have explored our own solar system first. There is plenty to keep us busy here. But it is fun to speculate, and no harm in making better telescopes.
VEGA - oagus_velas
Feb 03, 2012
This comment has been removed by a moderator.
Parsec
5 / 5 (2) Feb 03, 2012
One, even baseball sized celestial jaywalker would do catastrophic damage to any craft

Baseball? How about a speck of dust. :)

Actually, the problem is even worse than that. Even in interstellar space outside of a dust cloud, the density of gas is on the order of a few atoms per cubic meter. Traveling at .5c would mean huge amounts of matter impacting the spacecraft on a continuous basis. It would be going fast enough to constitute a tremendous radiation density.
Kedas
2 / 5 (2) Feb 03, 2012
Let's put thing around a bit and assume there is an advanced life form there.
- Assume there is a SETI network there would they pick us up?

- Can we already say for certain there is no made up signal transmitting there in our direction.

P.S. It would have been 'cool' if it was called GJ 666 ;)
Gino
1 / 5 (10) Feb 03, 2012
The name Vulcan is already taken for the Earth twin that orbits at exactly the same rate as us and is always behind the Sun
antialias_physorg
4.2 / 5 (5) Feb 03, 2012
. A planet with 5 earth masses and a radius 5

But at the same density a planet with 5 times the mass would not have 5 times the radius.

Let R be the radius of Earth, then the radius of something as dense as Earth with 5 times the mass would be R times the cube root of 5 (roughly 1.7 times the radius of Earth)

Since mass/gravity is a bit higher then, if we postulate that the planet is made up of the same materials as Earth, it would be packed more tightly. So the radius would be slighty less than that.

Surface gravity/acceleration is given by
g = G * M / r
(G = gravitational constant, M = mass, r = radius)

Plugging stuff in I get roughly 1.7g
(no guarantee for accuracy. I didn't double check)

if one were to achieve 0.5c, how would collision avoidance be carried out?

It wouldn't. Even the impact of a grain of sand has the force of a small atomic bomb at those speeds. No way you can look ahead far enough to detect/avoid that.
wukka
2 / 5 (3) Feb 03, 2012
"Gravitational forces for a planet 4.5 times that of earth will be a problem for life similar to earth."

Depends on the planets density and how far the surface is from the centre of mass.


We will all find out soon enough, The Tall Man will turn us into dwarves, and send us to the Phantasm slave planet.
http://www.imdb.c...0079714/
daywalk3r
3.5 / 5 (15) Feb 04, 2012
if one were to achieve 0.5c, how would collision avoidance be carried out?

It wouldn't. Even the impact of a grain of sand has the force of a small atomic bomb at those speeds. No way you can look ahead far enough to detect/avoid that.

As Parsec allready pointed out, even single static particles in free space/vacuum (like protons/atoms) would pose a quite serrious issue. Your craft would probably evaporate shortly after reaching those speeds, unless propperly "shielded" by some kind of a deflector.

Now that's easy said than done.. Incredibly strong and huge magnetic fields (extending hundreds of km in front of the craft) will be needed to provide at least some degree of deflection to make transport at speeds >0.1c at least hypotheticaly feasible. Sort of like a "bubble" in front of the moving craft to "purify" the vacuum by pushing particles out of the line of flight.

That's why I think that even if we had the propulsion technology, we are still FAR from practical apps.
Henrik
Feb 04, 2012
This comment has been removed by a moderator.
antialias_physorg
4.2 / 5 (5) Feb 04, 2012
Now that's easy said than done.. Incredibly strong and huge magnetic fields (extending hundreds of km in front of the craft) will be needed to provide at least some degree of deflection

Wouldn't do you any good. Neutral particles aren't affected by magnetic fields. It's not only protons and electrons out there. Whole atoms (or anything bigger) wouldn't care.

Hundreds of kilometers wouldn't be enough in any case. At that speed you'd be traversing a thousand kilometers every 0.007 seconds. Hardly enough time to push anything 10 meters out of the way (assuming that's the diameter of your craft)

More evidence that cosmic evolution models ("swirling clouds of gas") are incorrect.

Finding unepexted stuff is the lifeblood of science. It gives us a chance to refine theories. Science is not immutable. But the finding in no way causes the model to be incorrect. Only in a digital world would that be true. But such worlds only exist in fairy tales (read: the Bible)
Henrik
Feb 04, 2012
This comment has been removed by a moderator.
antialias_physorg
4.3 / 5 (6) Feb 04, 2012
I think youneed to look up the definition of the word 'unlikely'.

Hint: It's not synonymous with 'impossible'.

Getting 5 times heads in a row on a coin toss is unlikely. It in no way invalidates the assumption that you have a balanced coin.
Henrik
Feb 04, 2012
This comment has been removed by a moderator.
antialias_physorg
4.3 / 5 (6) Feb 04, 2012

Neither is it impossible to have a hundred times rouge at roulette. But by that time the players will probably demand an alternative explanation from the croupier than "chance".

Yes. But YOU are claiming that because we have ONE observation of an unlikely event we should conclude that the model is false.
That's like saying "I got heads twice in a row - therefore the coin MUST be unbalanced"
That's just dumb.
Henrik
1 / 5 (10) Feb 04, 2012
have ONE observation of an unlikely event


I never said that. You are attacking a straw man.

This is just the latest of many observations that seem to be at odds with the scientific paradigm on stellar evolution. To rescue the theory, it has to become ever more complicated, being supplemented with ad hoc assumptions.
antialias_physorg
5 / 5 (6) Feb 04, 2012
They are not 'add odds' with anything. These are things that are interesting (and hence are reported). You don't get reports of all the triple star systems around which no planets have been found.

Much like you would report getting 10 heads in a row, but wouldn't report a heads-tails-tails-heads-heads-heads-tails-haids-heads-tails series. Because it's not interesting.

Look: No one is saying science already knows everything (that would be antithetical to what science IS). But your 'observations' of things that seemingly 'show' that the current model is completely false is just so far over the insanity horizon (and accelerating) that its not even funny to poke at.
TheGhostofOtto1923
3 / 5 (4) Feb 04, 2012
Look: No one is saying science already knows everything (that would be antithetical to what science IS). But your 'observations' of things that seemingly 'show' that the current model is completely false is just so far over the insanity horizon (and accelerating) that its not even funny to poke at.
Henrik should know that his posts only make his humongous sky fairy theories look very bad, and science look very good. Keep up the excellent work henrik.
Henrik
Feb 04, 2012
This comment has been removed by a moderator.
thales
3.7 / 5 (9) Feb 04, 2012
Star formation will never be known by science because the alledged process cannot be observed on a human timescale.


So you think any process that takes longer than 120 years can never be "known by science"? I don't even
roboferret
5 / 5 (4) Feb 05, 2012
Tree formation will never be known by science because the alledged process cannot be observed on a human timescale.

Sounds a bit silly now doesn't it?
Henrik
1 / 5 (11) Feb 05, 2012
So you think any process that takes longer than 120 years


Who mentioned 120 years? Not me.
Henrik
Feb 05, 2012
This comment has been removed by a moderator.
Shinichi D_
3.4 / 5 (5) Feb 05, 2012
Tree formation will never be known


Tree growth can be observed over several years. Star formation however is supposed to occur on timescales that lie beyond any human existence or meaningful human observation.


So continental drift is nonexistent. Or evolution for that matter

antialias_physorg
5 / 5 (6) Feb 05, 2012
Star formation will never be known by science because the alledged process cannot be observed on a human timescale.


You're very quick with your 'never's. It's a sign of a small mind.

a) YOU don't know what a human timescale is. We could crack the code to immortality (biologically or technically). Or we could simply keep records for a long time of our observations

b) Looking outward means looking into the past. We see stars in all sorts of stages of being formed. It's not necessary to see ONE star go through the full rigmarole from dust cloud to first light in order to get a good picture of how stars form.

Furthermore, the underlying physics is questionable and many star systems go against the predictions. Even our own solar system cannot be explained by swirling dust clouds.

Care to support all of that with something other than "I said so"? You're just making stuff up.
Henrik
1 / 5 (11) Feb 05, 2012
We see stars in all sorts of stages of being formed


Only if you already assume star formation is true. That would make it a fine example of circular reasoning. The idea that these stages represent stellar death rather than birth is equally valid. It is also more plausible since we actually have observed star deaths (supernovae).
Lurker2358
1 / 5 (4) Feb 05, 2012
Agreed. I vote it should be named Vulcan.

Can one of you numbers folks tell me at 4.5 times the mass of Earth, what would the gravity be like?


Assuming similar composition and average density to the Earth, it would be um 4.5 times as volumous.

So IF they have the same average density then it has surface gravity equal to the cubed root of the mass, expressed in terms of Earth gravity, which in this case is 1.65g, or 16.31m/s^2 acceleration.

Again, that is just an assumption.

If it is very high in iron and other heavier metals, the radius may be lower, which would mean higher gravity.

If it is very iron poor, the radius would be higher, and so lower surface gravity.

To put that in perspective, this is actually one of the most Earth-like planets ever discovered both in terms of temperature and surface gravity.

But there are still tons of variables involved to have habitability. Needs both nitrogen and CO2 atmosphere, etc.
Henrik
Feb 05, 2012
This comment has been removed by a moderator.
bewertow
5 / 5 (6) Feb 05, 2012
No, you have no scientific integrity. You so desperately cling to the idea of a sky fairy who is his own father that you mindlessly attack anything that challenges your outdated and silly ideas.

antialias_physorg
5 / 5 (3) Feb 05, 2012
But there are still tons of variables involved to have habitability. Needs both nitrogen and CO2 atmosphere, etc.

Don't forget the O2 (which is, on our world, the product of biological processes). Unlikely to come by that (at the exact right percentage to boot) on a lifeless world.
aroc91
5 / 5 (1) Feb 06, 2012
We see stars in all sorts of stages of being formed


Only if you already assume star formation is true. That would make it a fine example of circular reasoning. The idea that these stages represent stellar death rather than birth is equally valid. It is also more plausible since we actually have observed star deaths (supernovae).


lolwut? Assumptions have absolutely no bearing on OBSERVATION.

http://www.scienc...4842.htm