[Science] Planet Discovered in 3-Star System


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Last one for now guys :p

A newly discovered planet has bountiful sunshine, with not one, not two, but three suns glowing in its sky.

It is the first extrasolar planet found in a system with three stars.  How a planet was born amidst these competing gravitational forces will be a challenge for planet formation theories.

"The environment in which this planet exists is quite spectacular," said Maciej Konacki from the California Institute of Technology. "With three suns, the sky view must be out of this world -- literally and figuratively."

The triple-star system, HD 188753,is located 149 light-years away in the constellation Cygnus.  The primary star is like our Sun, weighing 1.06 solar masses.  The other two stars form a tightly bound pair, which is separated from the primary by approximately the Sun-Saturn distance.

"The pair more or less acts as one star," Konacki told SPACE.com. 

The combined mass of the close pair is 1.63 solar masses.

Using the 10-meter Keck I telescope in Hawaii, Konacki noticed evidence for a planet orbiting the primary star.  This newfound gas giant is slightly larger than Jupiter and whirls around its central star in 3.5-day orbit.  A planet so close to its star would be very hot.

Although other so-called hot Jupiters have been found in such close-in orbits, the nearby stellar pair in HD 188753 likely sheared off much of the planet making material in the proto-planetary disk that would likely have existed around the primary star in its youth.  Since this disk holds the construction materials for planets, there does not appear to be any safe place for this planet to have been assembled.

Snow line and migration

The heat coming from a nearby star frustrates the initial stages of giant planet formation -- the gluing together of planetary seeds, called cores.  Therefore, hot Jupiters are thought to form farther out -- beyond a theoretical limit called the snow line. 

"Past about 3 AU, it is cold enough to form ices and other solid material for building cores," Konacki said.  An AU is the distance between the Sun and the Earth -- about 93 million miles.

Once a sufficiently large core is built outside the snow line, the planet can start accreting gas and -- if the conditions are right -- migrate toward its sun. 

Although this scenario appears to work in most stellar systems, it has difficulty explaining the newly-discovered planet in HD 188753.  Of all the planet-harboring stars known, this is the closest that a stellar companion has ever been found. 

"The problem is that the pair is a massive perturber to the system," Konacki said.  "Together, these two stars are more massive than the main star."

Moreover, the pair goes around the primary along an oblong path that stretches from 6 AU out to 18 AU over a 26 year period.  This eccentricity increases the instability of the disk around the primary.  Konacki estimates that due to the gravitational perturbations from the pair, the proto-planetary disk would be truncated down to 1.3 AU, far within the snow line.

"How that planet formed in such a complicated setting is very puzzling. I believe there is yet much to be learned about how giant planets are formed," Konacki said.

Targeting multiple stars

Konacki hopes to find more planets around stars with companions.  About 30 extrasolar planets have been found around double-star systems, or binaries.  This is a small percentage of the total number of extrasolar planets, even though multi-star systems outnumber single star systems. 

The reason for this disparity is that the main technique for locating planets -- the radial velocity method -- is not well-suited for finding planets with more than one star.

"Single stars are much easier to work with, since the shape of the spectrum stays the same," Konacki explained.

By watching for wobbles in a star?s spectrum, astronomers can infer the gravitational tug from a nearby planet.  When there is a companion star, its light competes with that of the main star.  Konacki has developed a method to extract the planet wobbles from this messy, combined spectrum. 

He found this triple-sun planet in the first 20 stars he looked at.  He plans to survey about 450 stars in the future.

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holy moly, thanks for posting this! You know how big of a discovery this is? Binary stars systems have been found to contain planets, but a TRIPLE star system! wow! imagine the gravitational tugs this planet must experience.

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holy moly, thanks for posting this! You know how big of a discovery this is? Binary stars systems have been found to contain planets, but a TRIPLE star system! wow! imagine the gravitational tugs this planet must experience.

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Yes Mr. gut, other people can post Science topics also! :)

And yes, this is indeed a big discovery. I was reading an article not more than 2 days ago from 2002 I believe where some scientist was saying that planets couldn't really form let alone survive in a triple star system. Yeah right!

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this should signal to NASA that a succesor to Hubbles to be be built and sent up to orbit as soon as possible. Or at least a succesor(s) to the telescopes in Hawaii (which happend to be the biggest in the world currently)

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(Reuters) -- Astronomers have detected a planet outside our solar system with not one, but three suns, a finding that challenges astronomers' theories of planetary formation.

The planet, a gas giant slightly larger than Jupiter, orbits the main star of a triple-star system known as HD 188753 in the constellation Cygnus.

The stellar trio and its planet are about 149 light-years from Earth and about as close to each other as our sun is to Saturn, U.S. scientists reported on Thursday in the current edition of the journal Nature.

A light-year is about 6 trillion miles (10 trillion km), the distance light travels in a year.

If you stood on the planet's surface, you would see three suns in sky, although its orbit centers around the main yellow star among the trio. The larger of the other two suns would be orange and the smaller would be red, astronomers at California Institute of Technology said in a statement.

The new finding could upset existing theories that planets usually form out of gas and dust circling a single star, and could lead scientists to look in new places for planets.

"The implication is that there are more planets out there than we thought," the commentary said.

Caltech astronomer Maciej Konacki, who wrote the research article, refers to the new type of planets as "Tatooine planets," because of the similarity to Luke Skywalker's view of his home planet by the same name, with its multiple suns, in the original "Star Wars" film.

The fact that a planet can even exist in a multiple-star system is amazing in itself, according to Konacki. Binary and multiple stars are quite common in the solar neighborhood, and in fact outnumber single stars by some 20 percent.

But so far, most extrasolar planets -- those discovered outside our planetary system -- have been detected by watching for a characteristic wobble in the stars their orbit, reflecting the gravitation pull the planets exert on their suns.

This method is less effective for binary and multiple star systems, and existing theories said planets were unlikely to form in this kind of environment.

Konacki found a new way to identify planets by measuring velocities of all bodies in a binary or multiple star system.

Source :

http://www.cnn.com/2005/TECH/space/07/14/p...reut/index.html

Wow, that's cool. They're starting to find more and more planets in the 100 to 150 light year range (that's awfully close) and it's looking more and more like there are WAY more planets than we all thought.

Sure, alot of these planets are Jupiter sized planets, but the chances of life existing in a gas giant is still possible in the cooler upper atmosphere.

I hope we discover an "earth like" planet in my lifetime.

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Wow, that's cool. They're starting to find more and more planets in the 100 to 150 light year range (that's awfully close) and it's looking more and more like there are WAY more planets than we all thought.

Sure, alot of these planets are Jupiter sized planets, but the chances of life existing in a gas giant is still possible in the cooler upper atmosphere.

I hope we discover an "earth like" planet in my lifetime.

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Gas giants are believed to have high atmospheric pressures though. But Nature never fails to wow us so who knows......

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Wow, that's cool. They're starting to find more and more planets in the 100 to 150 light year range (that's awfully close) and it's looking more and more like there are WAY more planets than we all thought.

Sure, alot of these planets are Jupiter sized planets, but the chances of life existing in a gas giant is still possible in the cooler upper atmosphere.

I hope we discover an "earth like" planet in my lifetime.

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the worst part is, I'm sure earth-like planets are all around the galaxies and univers.... Problem is we just can't detect them.

It's much easier to detect a star, nebula or anything that emits light (or disorts in the case of black holes) which is the case in almost all discoveries..

I too would love to see discoveries of earth-like planetes with all kinds of elements mixed and not just dust and rocks and ice..

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The universe is such an amazing entity, yet we understand so little of it. Finding three stars in a single system really makes you wonder what else is out there and how large the universe really is.

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There is nothing like the study of cosmology, planetary science, and astronomy to make you feel like a spec of dust. because in the cosmological scale that's all we are, just cell based specs of dust that vary in shape. ;)

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I was reading an article not more than 2 days ago from 2002 I believe where some scientist was saying that planets couldn't really form let alone survive in a triple star system. Yeah right!

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maybe under normal circumstances, this cant happen.

but this surely can be an act of God.

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maybe under normal circumstances, this cant happen.

but this surely can be an act of God.

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Will you stop with your god things, if we wanted to hear about god then there would be a [definitive] thread regarding science vs god.

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Will you stop with your god things, if we wanted to hear about god then there would be a [definitive] thread regarding science vs god.

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lol, i know, i love the whole, its too difficult for us to explain right now given our technology so lets just say it was god crap... or the unintelligent intelligent design theory

the three sun thing is pretty crazy, if only i were born 100 years later...

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Yes Mr. gut, other people can post Science topics also! :)

And yes, this is indeed a big discovery. I was reading an article not more than 2 days ago from 2002 I believe where some scientist was saying that planets couldn't really form let alone survive in a triple star system. Yeah right!

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Aw man they found the planet that Pitch Black was filmed on....

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I'm wondering, would this planet be like one of Jupiter's moons that they used to think was active but it was just because of the immense gravitational pull. Is it like that?

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I'm wondering, would this planet be like one of Jupiter's moons that they used to think was active but it was just because of the immense gravitational pull. Is it like that?

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Jupiters inner moons deal with a gravitional tug of war, for example.

Io; the reason why this body is so geologically active is because it is being pulled one way from Jupiter and another way by the other bodies (when those bodies are nealry lined up on the other side of Io, or near)

do this:

Take a ball and put holes at the

top, fill it with water near to the top. Now hold the ball by pinching bothside with your fore finger and thumb on each side. Now gently pull and push on this ball and you will see that water begin to surface at the top through those holes.

That is what is believed to be the casue of Io's volcanic activity, Acoording to this theory Io will NEVER stop spewing nor become habitable.

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