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Amateur astronomers discover a planet with four suns
- tocomment 14y agoAny chance someone could make a diagram of the orbit for us? I really can't picture this? Does it make a figure 8 around the first two stars?
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- InclinedPlane 14y agoIt's a pair of binary stars with a planet orbiting one pair. To give you a conceptional model, imagine that Mercury is a star and then imagine that, say, Saturn and one of its moons are also stars. Now, obviously, orbital mechanics are going to change when you have all of these much more massive bodies in the system, but hopefully you get the picture. Edit: obviously not to scale, but maybe this helps: http://i.imgur.com/RJrOw.png http://i.imgur.com/RJrOw.png
- jmilloy 14y agoYour parent is asking how the planet orbits two stars, and probably how the 2-star-1-planet system orbits the two other stars. That is, "how does any body orbit two stars?"
- InclinedPlane 14y agoAnd I explained. How does the Earth orbit the Sun-Mercury system? It's no different than how a planet orbits a binary system from afar. The two stars orbit each other and then the planet orbits around both stars. And then that whole system orbits around another binary star system at a tremendous distance (1,000 AU, ten times farther away than Voyager 2 is from the Earth now).
- fusiongyro 14y agoIt's a little different; in our solar system, the Sun is one of the foci of the ellipse, whereas in a binary system that focus would instead be the center of gravity between the two stars.
- InclinedPlane 14y agoYes, though in this case the big star weighs nearly 4x as much as the little star, so it's a matter of one star shuffling around in a small ellipse with the smaller star in orbit, rather than a more intimate orbital dance if the stars had been closer in mass.
- drcube 14y agoAlthough Mercury in this instance is extremely insignificant, technically the earth orbits the center of gravity of the Sun and Mercury. Actually, the center of gravity of the Solar system as a whole, but I'm just going along with the GP.
- fusiongyro 14y agoGosh, how incredibly helpful.
- jobigoud 14y agoWe still have an analogy in the Solar system, Hydra and Nix orbit the Pluto-Charon binary. The barycenter of the Pluto system is outside the surface of the dwarf planet. http://upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Pluto_and_its_satellites_%282005%29.jpg/250px-Pluto_and_its_satellites_%282005%29.jpg http://upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Plu...
- TeMPOraL 14y agoNormally, it doesn't orbit two stars, it orbits their combined center of gravity (which, if the stars were the same mass, would lie exactly between them). Or to be more precise, both the stars and the planet together orbit their combined center of mass.
- JoeAltmaier 14y agoIts complicated. You can approximate it using the 2-star-center-of-mass, but thats skipping over important stuff. See, the stars are orbiting one another. At any time one may be closer/further away than the other from the planet. That makes the COG appear to 'wobble'. IF the planet is in something like a 'lagrange point' where it always sees both stars in the same relative position, then the COG approximation is true. Otherwise the planet will behave in a more complicated manner, and in fact may not have a stable orbit at all.
- tocomment 14y agoThanks. That is helpful. So there's no scenario where a planet could be in a figure 8 orbit? That would be amazing.
- jmilloy 14y agoIt's probably similar to other two-sun planets. The planet orbits around both stars at the same time, which are close together. http://galileospendulum.org/2011/09/15/a-planet-with-two-suns/ http://galileospendulum.org/2011/09/15/a-planet-with-two-sun...
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- SoftwareMaven 14y agoThe point the earth actually orbits around isn't actually in the middle of the sun. It is at the center of mass between us and the sun. A planet orbiting a dual star system will do the same thing, but the center of mass winds up being somewhere between the two stars.
- DanBC 14y agoThey were using Planet Hunters - which appears to be a crowd sourced "find interesting bits in all this data" website. (http://planethunters.org/ http://planethunters.org/)
- bdisraeli 14y agoI work for the group that made Planet Hunters. We have a variety of similar projects at http://zooniverse.org http://zooniverse.org, including four others we launched in the last month that have people classifying sea floor life, galaxies, cyclones, and bat calls.
- DanBC 14y agoThey're very cool projects! I've been noodling around for a bit. I'll register if I think I'll be any good, and I'll certainly be passing the URLs around to people if I think they'll be interested.
- ajasmin 14y agoCould someone explain how that site works? Are the amateur astronomers mentioned in the article user of planethunters.org who just happen to have been served the right pictures to work on? Is this Mechanical Turk type work or does it require serious scientific effort?
- wooptoo 14y agoMan, everything has to be quad core these days.
- zandorg 14y agoOverheating too, I guess.
- twmb 14y agoI wonder if it's a planet such that the surrounding stars' lights prevent any other starlight from being seen, except for once every few thousand years. One could only imagine a civilization that lives here and what would happen to society whenever the full night sky is occasionally seen...
- thanosbaskous 14y agoI know that you're being fatuous but in case anyone doesn't get the reference, check out Nightfall by Asimov - it's a classic sci-fi short story. http://www.uni.edu/morgans/astro/course/nightfall.pdf http://www.uni.edu/morgans/astro/course/nightfall.pdf
- DougWebb 14y agoThe planet is a Neptune-like gas giant, so no civilization there. It probably has big moons though, and with all the suns around they might be warm enough to develop life. I haven't done the math, but I'm guessing that when the moon is on the night side of the planet relative to the nearby stars, the location of the distant stars would cycle in basically the same way Jupiter does in our sky. It moves slowly relative to the background stars, but still rises and sets every day. I don't know the details and couldn't do the math if I did, but I'm guessing those stars at 1000AU can't be much brighter than our full moon is, maybe combined with the light pollution of a big city. I've lived outside of New York all my life, and my night sky still has stars in it. Not many, but enough to know they're there, and sometimes on a clear night I can see quite a few.
- pdonis 14y ago> I'm guessing those stars at 1000AU can't be much brighter than our full moon is They may well be fainter. According to Wikipedia, the Sun is about 400,000 times as bright as the full moon, on average: http://en.wikipedia.org/wiki/Apparent_magnitude http://en.wikipedia.org/wiki/Apparent_magnitude So if the Sun were 1,000 AU away from us instead of 1 AU, it would be a million times fainter (1,000 squared), or less bright than the full moon.
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- b_emery 14y agoTheir link to human vs machine is interesting: http://www.planethunters.org/science#human http://www.planethunters.org/science#human I wonder how good their machine learning is? I'd love to throw some support vector machines or neural networks at this stuff!
- sadga 14y agoA team at McGill made a "game" to find patterns in I think protein-folding or genome data, to leverage humans to identify patterns that their algorithms could not. http://en.wikipedia.org/wiki/Phylo_(video_game) http://en.wikipedia.org/wiki/Phylo_(video_game)
- InclinedPlane 14y agoI tracked down the original paper (http://arxiv.org/abs/1210.3612 http://arxiv.org/abs/1210.3612) and dug up some useful details. The planet in question is a gas/ice giant similar to Uranus with a radius 6 times that of Earth (nearly 80,000 km in diameter) with an as yet unknown mass (although it must weigh less than half of Jupiter's mass at the most). It orbits a pair of binary stars with a period of 138 days. The binary it orbits is an F dwarf star with 1.5 the Sun's mass and an M dwarf with 40% of the Sun's mass, they orbit each other with a period of 20 days. For reference, this translates to the two stars orbiting much closer than Mercury's orbit (around 0.17 AU) and the planet with an orbit close to that of Venus (around 0.65 AU, according to my calculations). This system is bound to another binary system of similar total mass (a G2 star similar in mass to our Sun and an M2 dwarf star with around half or less the mass of our Sun) at a distance of around 1,000 AU. At that distance the second binary system would merely be the brightest stars in the night sky of the planet. The two binary systems would orbit each other with a period of tens of thousands of years.
- ChuckMcM 14y agoI've tried about 8 different ways to modelling that and so far all of them have the planet being ripped apart as soon as its orbit is elongated by the traversing between the two pairs of binaries. Bizarre doesn't begin to describe it.
- JoeAltmaier 14y agoMaybe the orbit is perpendicular to the stars' plane of orbit?
- InclinedPlane 14y agoThis doesn't make sense to me. The two pairs of binaries are around 6 light-days apart. The gravitational forces they have on each other are miniscule, but they are persistent enough to cause the two systems to orbit each other with a period longer than the duration of human civilization.
- ChuckMcM 14y ago
- pm 14y agoBrian Aldiss referenced a similar kind of system in his Helliconia science fiction trilogy, where a planet orbited a small sun, which in turn orbited a much larger sun in a much longer orbit. Ironically, truth turns out to be stranger than fiction, seeing as this two binary systems are involved.