# Rare Five Star System Discovered



## mosaix (Jul 8, 2015)

http://www.bbc.co.uk/news/science-environment-33428506

_Astronomers have discovered a very rare system of five connected stars.

The quintuplet consists of a pair of closely linked stars - binaries - one of which has a lone companion; it is the first known system of its kind.

The pair of stars orbit around a mutual centre of gravity, but are separated by more than the distance of Pluto's orbit around the Sun.

The findings have been presented at the UK National Astronomy Meeting in Llandudno.

The unusual system lies 250 light-years away in the constellation Ursa Major. It was discovered in data gathered by the SuperWASP (Wide Angle Search for Planets) project._

The Universe continues to surprise.


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## Ursa major (Jul 8, 2015)

mosaix said:


> The unusual system [of five connected stars] lies 250 light-years away in the constellation Ursa Major.


I must say, this is bearly believable!


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## Stephen Palmer (Jul 8, 2015)

Read that this morning. Fascinating!


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## hardsciencefanagain (Jul 8, 2015)

Somehow,I knew post n.2 was coming


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## DrMclony (Jul 8, 2015)

Very interesting. It would make for a fun time if you lived there...


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## hardsciencefanagain (Jul 8, 2015)

also,e.g.
http://www.ras.org.uk/news-and-press/2661-a-five-star-doubly-eclipsing-star-system


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## Dennis E. Taylor (Jul 8, 2015)

'Nightfall' looking not quite so unbelievable, suddenly.


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## Ray McCarthy (Jul 8, 2015)

Except any planet surrounded by all five might not last long, but I thought of Nightfall too.

It's not clear where you would have a stable orbit for a planet with a half sensible about of radiation.

Possibly around either of the two groups (one Binary and one Trinary) which orbit around a common centre



			
				Dr Lohr said:
			
		

> This is a truly exotic star system. In principle there’s no reason it couldn’t have planets in orbit around each of the pairs of stars. Any inhabitants would have a sky that would put the makers of Star Wars to shame – there could sometimes be no fewer than five Suns of different brightnesses lighting up the landscape. Days would have dramatically varying light levels as the different stars were eclipsed. They would though miss out on night for a large part of their ‘year’, only experiencing darkness (and a night sky) when the stars were on the same side of their world.


They would have nights though. I think the actual Nightfall scenario is impossible.
http://www.ras.org.uk/news-and-press/2661-a-five-star-doubly-eclipsing-star-system


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## Brian G Turner (Jul 8, 2015)

Ray McCarthy said:


> Possibly around either of the two groups (one Binary and one Trinary) which orbit around a common centre



Else around the common centre of gravity within the orbit of the five. Though opportunities to become slingshot-ed out may be significant under many conditions.


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## Ray McCarthy (Jul 8, 2015)

Brian Turner said:


> Else around the common centre of gravity within the orbit of the five


I'd have to model it, but I think you'd need a stellar mass to be stable in the centre. I think the wobble of even something like Jupiter would result in it moving toward which ever group of stars had more mass. 

A planet in orbit around either group would not want to have too big an orbit either. It's very interesting.


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## K. Riehl (Jul 9, 2015)

When Cixin Liu wrote _The Three-body Problem_ in 2006 he developed a story around life in a three star system and how you can never predict anything that comes next. So far humans can't solve the 3 body maths.


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## Ray McCarthy (Jul 9, 2015)

But I think you can build a model and run it backwards and forwards ...


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## Venusian Broon (Jul 9, 2015)

Brian Turner said:


> Else around the common centre of gravity within the orbit of the five. Though opportunities to become slingshot-ed out may be significant under many conditions.



The centre of mass of that system would seem to me to be a pretty clean area, as I would guess it's quite unstable - with five large objects around it in various configurations will push and pull objects into trajectories that see them being, as you say, slungshot out. My first guess would be as Ray says, very tight orbits around the stars themselves (or the binary pairs of stars) are probably the best place for planets to survive. Even then I would be surprised if any planet really lasted that long in a regular orbit. 

However it this system may surprise still and there may be a long-term stable solution for a planet to orbit somehow!


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## Ray McCarthy (Jul 9, 2015)

Venusian Broon said:


> very tight orbits around the stars themselves (or the binary pairs of stars) are probably the best place for planets to survive.


The stars are not as hot as ours.

The minimum distance of orbit: Large enough to orbit the centre of gravity of Binary or Ternary system with stability
The maximum distance of orbit : Small enough not to be unduly affected by the other star system. 
Between these two limits there may be a very complex orbit.
Stable orbit of just one star in Binary or Ternary system is possible but needs much greater star separation than the two groups have. The overall separation is about size of "orbit of pluto" (diameter or radius?), so orbit (1) sounds feasible and might be in goldilocks zone for one of the two groups.  Planets have been detected on Binary star systems.

It would be interesting to see if either the Binary or Ternary system has a stable "Goldilocks" zone.

Prolonged observation (wobble and brightness variation) may reveal presence of planets.

With even better space telescope we will in future be able to do spectroscopic analysis of the starlight  direct and via the edge of a planet's atmosphere. This will be MUCH better and longer range than SETI radio search as certain combinations and proportions of gases are far more likely from industrialisation than  any natural process.


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## Brian G Turner (Jul 9, 2015)

K. Riehl said:


> So far humans can't solve the 3 body maths.





Ray McCarthy said:


> But I think you can build a model and run it backwards and forwards ...



IIRC, chaos principles means that in real life there will always be tiny variations that over time will result in significant deviations.


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## Ray McCarthy (Jul 9, 2015)

@Brian Turner
Yes. However it gives an idea of it, albeit that it's less accurate the longer you run it.
That's why the TLE for objects in earth orbit are updated by observations. With time even an earth orbit simulator becomes less accurate:
I use Orbitron to predict when weather satellites are passing. Then a 137MHz FM receiver plugged into PC decodes the maps. Also passes of ISS.
It has to be updated periodically or the times become too inaccurate.
http://www.stoff.pl/
It looks wonderful using a projector to fill a wall.
You can select specific groups of object of interest.


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## Vertigo (Jul 9, 2015)

I'm not so sure the night- or day-time sky would be all that impressive. The stars are separated into two groups and those two groups are separated by rather more than the orbit of Pluto. The stars are not particularly bright (cooler than the sun). The Sun from Pluto is, I believe, not particularly bright. So even if you were on the night side of your planet with respect to the your local group the other group would probably not give much more light than, say, our moon. I haven't done the sums on this so I can't say definitely but I suspect that either group would look from the other not much more than a particularly bright star.

If you were orbiting the three sun group then your daytime brightness would change as they eclipse each other, yes, but I think that's about it. if you orbited only the binary in the three star group (ie your orbit goes between the binary and the outlier) then I suspect your planet would be torn apart by changing tidal forces.

Actually on a quick review I'm not sure what that article is on about. It states the two groups of stars are "are separated by about 21 billion km, rather larger than the size of Pluto’s orbit around the Sun." Umm, according to a very little bit of googling Pluto orbits around 6 billion km from the sun and even if they mean Pluto's orbital 'diameter' that's only about 12 billion km? I'm left scratching head  I really can't get their numbers to add up?


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## Ray McCarthy (Jul 9, 2015)

Vertigo said:


> "are separated by about 21 billion km, rather larger than the size of Pluto’s orbit around the Sun."


Yes at 21 billion km, it might be like moonlight. There is a big difference outside artificial light pollution zones between Full moon and new moon though. That sounds like about 2.5x or 5x Pluto's max distance from sun (Pluto's orbit is very elliptical indeed), I'm not sure if Wikipedia is referring to major diameter of ellipse or distance from sun.

Orbiting the binary and seeing the Trinary group in distance might be interesting though.


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## Vertigo (Jul 9, 2015)

I wasn't too sure either but I have seen Pluto's orbit listed as around 4.5 billion km minimum and around 7.8 billion km maximum, so however you look at it all those articles seem wrong? And applying Occam's razor therefore suggests I've got something very wrong! 

However I agree with you, I do think you would be able to see the 'dance' of the other binary pair. I imagine it would create some interesting mythology! And as you say particularly so if the other pair is actually the three star group.


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## Ray McCarthy (Jul 9, 2015)

Even here we already have mythos with Triads (everywhere in old Celtic, e.g. the Morrigna) and Triad elements (3 in 1, Christianity) and also Dualist (Ying / Yang,  Zoroastrian) and Dualist elements (God & Satan etc).
Many more examples.
I have a theory about the alleged story of Patrick explaining the Trinity with a Shamrock. (Patrick was certainly real). Even pre-Celtic Neolithic were into triple spirals carved on rocks.

But are constellations and planets named AFTER existing beliefs in beings, or do they inspire the beliefs? I suspect the former. Though while in English we have the Man in the Moon, in Chinese and Celtic tradition it's the Rabbit and the Hare (I think the Normans brought the rabbit to Ireland).


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## Vertigo (Jul 10, 2015)

But then it was Mars' red colour that give it its association with war. And my point here is that it wouldn't be a static trio of stars but a trio of stars that would be 'dancing' around each other. That would surely get the primitive mind working!


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## Ray McCarthy (Jul 10, 2015)

Could be.


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