Planet with four stars discovered by citizen astronomers

[Doktor]

A planet that orbits a pair of stars and has a second pair of stars revolving around it has been discovered by volunteers using the Planethunters.org website.

Out of the thousands of planets that have been discovered outside of our solar system, only seven of them have been found to orbit binary stars -- these are known as circumbinary planets. None of these circumbinary planets have been found to have another pair of stars circling them.

The planet, called PH1 after the PlanetHunters website, is believed to be a gas giant a little larger than Neptune and six times the size of Earth, located around 5,000 light-years away. It was found by two US volunteers on the site -- Kian Jek of San Francisco and Robert Gagliano from Arizona -- who spotted faint dips in light caused by the planet passing in front of its parent stars.

The discovery was then confirmed by a team of professional astronomers from Oxford University, Yale University and Adler Planetarium using the Keck telescopes located in Hawaii. Astronomers don't know how such a four-star system remains stable enough to not pull PH1 apart.

Chris Lintott from Oxford University says: "It's fascinating to try and imagine what it would be like to visit a planet with four Suns in its sky, but this new world is confusing astronomers -- it's not at all clear how it formed in such a busy environment."

The discovery will be presented on 15 October at the Division for Planetary Sciences annual meeting in Reno, Nevada in a paper authored by Meg Schwamb from Yale University. She said: "The discovery of these systems is forcing us to go back to the drawing board to understand how such planets can assemble and evolve in these dynamically challenging environments."

The news follows the discovery in August 2012 of two planets -- Kepler-47b and Kepler-47c -- orbiting two Suns. The system was discovered by Nasa's exoplanet-hunting Kepler telescope.

Planet with four stars discovered by citizen astronomers (Wired UK)

[Doktor]

How cool, odd and confusing all at once this is, I am speechless

[Chogy]

My first thought was "wildly unstable" but apparently not.

A binary pair of center stars has a nutating CG that a planet might be able to find stability in orbit about, but 2 additional stars? All I can think of is that the 3rd and 4th stars must be white dwarfs much, much lighter than the binary pair.

Imagine a solar system like this: Anchored by a major-league, massive primary star of 4 or 5X the mass of Sol, orbited by a series of rocky planets and gas giants, and toss in a white dwarf or even a light main-sequence star at the edge of this solar system. A very heavy primary would allow for stable orbits much farther out than our own planets. And the white dwarf would have a stable orbit around the primary.

It would also illuminate the outer portions of the solar system. The dozens of moons that might surround the gas giants could all be in the "goldilocks zone" due to the dwarf, and be teeming with life! They'd have outrageous day/night cycles and continuous eclipses.

[Double Edge]

A binary pair of center stars has a nutating CG that a planet might be able to find stability in orbit about, but 2 additional stars? All I can think of is that the 3rd and 4th stars must be white dwarfs much, much lighter than the binary pair.

agree, the article did't mention whether the outer stars are smaller or not.

[gunnut]

Well, couldn't we reduce the 4 stars down to a single center of mass? The center will move (relative to the system), but it's essentially still a single point relative to the planet.

[Doktor]

^^ Was thinking the same, eventually the 4 suns will collide and form one sun.

[FJV]

One wonders how Gallileo would explain that one to the pope.

[Monash]

Meanwhile another group of astonomers have just announced a very important discovery. Apparently they have detected a planet with about the mass of Earth orbiting a star in the Alpha Centauri system (Alhpa Centauri B to be precise) which is of course the nearest star system to Earth. The B component is also very much like the Sun in terms of size and luminosity.

Their observations are based on 4 years of observations designed to detect "wobbles" in the star as the planet orbits around it and these measurements indicate a planet is orbiting Centauri B every 3.2 days. So don't pack your bags just yet.

The interesting thing from my perspective is that while these results need to be confirmed further analysis might just push the orbit out a bit further (it would be hard to get closer). Also until now its apparently been an open question whether binary systems like this one would provide stable environments for planet formation other than the occasional "freak" world. But now a planet has been detected orbiting in a binary system which is also our closet neighbor this means the odds of it being such a freak come way down. In fact it would tend to mean planets are the norm for such systems which makes both Centauri A and B very interesting. There may well be other worlds orbiting these stars with more Earth like conditions. Poor old Proxima never seems to get a mention in the press though.

[Double Edge]

Well, couldn't we reduce the 4 stars down to a single center of mass? The center will move (relative to the system), but it's essentially still a single point relative to the planet.

Do not follow ?

The interesting or rather puzzling point here is that the force of attraction did not destroy the planet.

And Chogy is right about the outer pair of stars being smaller, they have to be smaller or they would not be revolving around the inner pair to begin with. And with that maybe not powerful enough to destroy the inner planet either.

This is one of those flukes. Stars rotating around other stars. If you can get two suns into a system then why not more. The inner pair of suns must be massive in comparison.

[kato]

Why white dwarfs?

Brown dwarfs would be a whole lot more likely. And brown dwarfs orbiting other stars aren't rare.

[gunnut]

Do not follow ?

The interesting or rather puzzling point here is that the force of attraction did not destroy the planet.

And Chogy is right about the outer pair of stars being smaller, they have to be smaller or they would not be revolving around the inner pair to begin with. And with that maybe not powerful enough to destroy the inner planet either.

This is one of those flukes. Stars rotating around other stars. If you can get two suns into a system then why not more. The inner pair of suns must be massive in comparison.

The planet would be destroyed if the gravitational force, or tidal force, tears the planet apart.

The 4 starts can be treated as a single point of mass relative to the planet. The planet orbits around this point. This point might "wobble" relative to the planet. That would be the main problem for the planet, not the gravity well.

[Double Edge]

Hrm, it seems a reread of the OP's article on my part is in order

A planet that orbits a pair of stars and has a second pair of stars revolving around it..

The second pair are smaller than the planet and revolve around the planet itself. How odd is that (!)

One wonders how Gallileo would explain that one to the pope.

We go around the sun buuuut in some parts of the universe its like you said....

The 4 starts can be treated as a single point of mass relative to the planet. The planet orbits around this point. This point might "wobble" relative to the planet. That would be the main problem for the planet, not the gravity well.

I'm thinking instead of two moons this planet just has a pair of small suns around it.

How did that happen ?

A bunch of small stars cruising around get trapped by a planet and end up as its satellites. The planet in effect saves them from being devoured by the central pair of stars.

Wierder and wierder.

[gunnut]

I'm thinking instead of two moons this planet just has a pair of small suns around it.

How did that happen ?

A bunch of small stars cruising around get trapped by a planet and end up as its satellites. The planet in effect saves them from being devoured by the central pair of stars.

Wierder and wierder.

I don't think that's what the article meant.

I think the article meant a smaller binary system orbits around a larger binary system, then this planet orbits around all of them.

A star needs to have a certain mass to start the nuclear reaction. Anything less then it fizzles. Planets by definition have lower mass than stars because they did not ignite. A star cannot orbit around a planet because a star has so much more mass than a planet. Well...it orbits, the the center of mass of the star/planet system is within the star itself. So it looks like the planet orbits around the star while the star stays stationary.

[Double Edge]

I don't think that's what the article meant.

I think the article meant a smaller binary system orbits around a larger binary system, then this planet orbits around all of them.

ok, then what you said earlier makes sense.

When i first read the article i though pair of stars, a planet revolving around them and then another pair of stars revolving outside. This gave me the idea of the planet being pulled by the two star pairs as its sandwiched between.

A further read gave me another idea.

And yours is the third interpretation. There is some ambiguity here.

A star needs to have a certain mass to start the nuclear reaction. Anything less then it fizzles. Planets by definition have lower mass than stars because they did not ignite. A star cannot orbit around a planet because a star has so much more mass than a planet. Well...it orbits, the the center of mass of the star/planet system is within the star itself. So it looks like the planet orbits around the star while the star stays stationary.

yep i find the idea of stars revolving around a planet difficult to fathom. Its just not what happens usually.