Big Dipper "Star" Actually a Sextuplet System 88
Theosis sends word that an astronomer at the University of Rochester and his colleagues have made the surprise discovery that Alcor, one of the brightest stars in the Big Dipper, is actually two stars; and it is apparently gravitationally bound to the four-star Mizar system, making the whole group a sextuplet. This would make the Mizar-Alcor sextuplet the second-nearest such system known. The discovery is especially surprising because Alcor is one of the most studied stars in the sky. The Mizar-Alcor system has been involved in many "firsts" in the history of astronomy: "Benedetto Castelli, Galileo's protege and collaborator, first observed with a telescope that Mizar was not a single star in 1617, and Galileo observed it a week after hearing about this from Castelli, and noted it in his notebooks... Those two stars, called Mizar A and Mizar B, together with Alcor, in 1857 became the first binary stars ever photographed through a telescope. In 1890, Mizar A was discovered to itself be a binary, being the first binary to be discovered using spectroscopy. In 1908, spectroscopy revealed that Mizar B was also a pair of stars, making the group the first-known quintuple star system."
Only 78 light years away (Score:5, Interesting)
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And being stars, even dim, they're easily some of the most visible objects in the sky. Consider just the Solar system and how many things in it that we don't know about. There's probably more we don't know about just within the heliopause than there is that we do know about.
Re:Only 78 light years away (Score:4, Informative)
Actually, that chart only says that there are about 70 stars whose distance is approximately 80 l.y. from here.
The cumulative total is more than that.
2539 stars within 80 light years (Score:4, Informative)
Indeed. And what an odd way to draw a chart, omitting a key to what counts as "80 light years". Does it count stars 80.1 light years away? 80.5? 82? Probably (79.5,80.5], but I've never seen "at" have an uncertainty of three trillion miles.
The source for that chart says there are 2539 stars within 80 light years (24.53 parsecs).
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Well, ya know, as anyone who watched the economy recently can tell you, a trillion ain't what it used to be...
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stars_on_sphere(R) = m R + b
From the graph it appears m = 5 / 6 and b = -1. The cumulative total suggested by the graph would then be the integral:
stars_within_distance(R) = Integral( 5 R / 6 - 1 ) = (5/12) R^2 - R
At 80 l.y. that is around 2600 stars
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Surprising indeed. There are only about 70 stars within 80 light years of us [wikimedia.org]
That is possibly correct, I don't know an awful lot about it, but that's not what that graph you linked to says. It says there are about 70 stars at a distance of 80 light years. If you want to know the number of stars within 80 light years, then you need to look at the area below the curve. Looks like about (80 * 65) / 2, about 2600 stars.
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Re:Only 78 light years away (Score:5, Interesting)
The surprising thing is that this is only about 80 light years away. That's practically our next door neighbor.
And if that star has a planet that had a species that had a SETI fifty years ago, they would have to keep searching for another twenty to forty years to pick up evidence of Earth having an intelligent species. They'd be waiting until 2119 before they heard the first human voice.
I'm curious, does anyone know how many stars there are within a hundred light year radius of the sun? My googlefu is weak today...
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And if that star has a planet that had a species that had a SETI fifty years ago, they would have to keep searching for another twenty to forty years to pick up evidence of Earth having an intelligent species. They'd be waiting until 2119 before they heard the first human voice.
And in 2200 the 2000kg tungsten slugs traveling at .9c begin crashing into the earth
Re:Only 78 light years away (Score:5, Insightful)
at .9c I'm pretty sure they would be crashing through the earth. Not that it would matter, at least not for very long.
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Funny comment, but I seriously doubt a 2k slug going .9c could even breach the crust and hit the mantle. The crust is ~50 miles thick. People can't grasp just how big the earth is. Sure at .9c it would likely kill everything within a few thousand miles except for the bacteria and send the earth into a very long ice age, but it's not going to penetrate the core or go through the planet. If something were physically large enough and moving fast enough to penetrate the planet it's not going to punch a hole thr
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But the sheer force of speed is also beyond people's grasp. At 0.9c it doesn't matter what it is, it's got kinetic energy enough to be more than a bomb even if it's full of feathers. A quick search indicates the formula is E_k = mc^2( 1/(v/c)^2 -1 ) that for a 2000 kg projectile at 0.9c would be 7.7*10^20 joules or 183 gigatons. And it's not spherical, 99% of the force will be in the direction of the impact like a shaped detonation. I'd rather not check what that'll do.
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"Through" is just another way of saying "into and then out of." And I doubt anyone would be around for the second part, so "into the earth" works for me. =)
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I'm still trying to find intelligent life on Earth, if these Aliens can find some I'd appreciate them contacting me.
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Intelligence is relative. A housecat is incredibly intelligent, compared to an omeba. We are incredibly intelligent compared to the species we evolved from. Compare us to whatever we become in another five million years and you're right, there is no intelligent life on earth.
OT - your sig:
How about +5 troll? [slashdot.org]
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I think what happens is that people get interested in the latest thing and we don't fill in all the gaps of knowledge in between. Its kinda like that whole
thing with water being spun really fast. It seems like its something simple, but its just one of the gaps in knowledge that occur when people jump ahead to the
latest thing. Its also probably why the U.S. has such large areas of nothing in between Illinois and California. Sure there are cities and such, but its not nearly as developed as say PA or OH are.
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"Its kinda like that whole thing with water being spun really fast"
Huh? Do you have a link to describe what you are trying to say?
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It may be the same reason why people go everywhere on the planet but don't even know their own home town: It's not that interesting to look at stuff that's "always been 'round" anyway. You wouldn't expect some new insight from something that has been studied for centuries, would you? It's far more likely to make that headline news discovery somewhere where nobody looked before.
In case anyone was wondering... (Score:5, Informative)
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The handle bend isn't really a star as much as it's an asterism, of which Mizar is the prominent member... Alcor is the much dimmer (still visible) partner. Contrary to the article, it's not merely a minority opinion that Mizar and Alcor comprise a false binary... calling the whole thing a sextuple system might be a bit of an exaggeration.
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Bill
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I'm also not from the states and am at a loss as to why it's called the bigger dipper. Could anyone inform me?
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Bill
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Before any Spelling Nazis get a hold of it, it is "Ladle!"
Bill
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Not quite. Ursa Minor == Little Dipper. The pleiades (or Subaru in Japan, look at their logo), though some confuse it as the little dipper. Ursa Major != Big Dipper. The Big Dipper is a *part* of Ursa Major.
Sorry, but I worked in a planetarium for a number of years.
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Technically the big dipper, or plough in most of England, is an asterism (a recognizable pattern of stars that is NOT a constellation) composed of stars that are part of the constellation Ursa Major (the big bear).
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More to come (Score:2, Informative)
It just goes to show you that there's always something more to learn.
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2*2 form Mizar, and 2 form Alcor; all six stars are gravitationally bound, and to the (untrained) naked eye look like a single star.
Actually Mizar and Alcor are visibly distinct to somebody with a good eye.
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"four-star Mizar system".
Re:Actually a quadruple... (Score:5, Informative)
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(Technically not, as--if you read carefully--it is mentioned that Kalgash is near the galactic core... but it's an interesting thought regardless.)
obvious logical deduction: (Score:2)
in the year 2110, the mizar-alcor system will be discovered to actually be a septuple star system
Re:obvious logical deduction: (Score:5, Funny)
More likely they'll be discovered to be giant glowing tribbles. How else do you explain it going from one star to six in just a few hundred years? ;)
Use extrapolation instead (Score:2, Funny)
So what you're saying... (Score:2)
So what you're saying is that it's stars all the way down?
I think you misunderstood. (Score:2)
AU means astronomical unit, not atomic unit. In your case, the measurement in Bohr radius doesn't qualify.
I suggested this... (Score:4, Funny)
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FTA (Score:2)
That group has also recorded a rough spectrum of the star, which Mamajek says confirms his prediction that the companion is a cool and dim M-class dwarf star.
...so it should at least have Roddenberries
Ancients needed glasses? (Score:2, Insightful)
FTFA: "In ancient times, people with exceptional vision discovered that one of the brightest stars in the Big Dipper was, in fact, two stars so close together that most people cannot distinguish them."
In ancient times the atmosphere was cleaner than now, and had a lot less light pollution from towns. Yet it apparently took "exceptional vision" to see Alcor and Mizar as separate stars. I must have phenomenal eyesight then to be able see them any night it isn't cloudy.
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I believe they were meaning that the bigger of the two you can see was found to be a binary, not that the two you see were found. So in other words, Mizar A and B in the 1700s, Alcor was discovered much earlier as it is easy to see that it is there.
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Naw, TFA is talking about distinguishing Alcor and Mizar as distinct stars with the naked eye. It took telescopes to resolve Mizar as the Mizar A and B system.
Personally, I haven't been able to see Alcor/Mizar with the naked eye on a cloudless night far away from cities and I don't need glasses, so maybe the OP just has exceptional vision.
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Mizar/Alcor are distinguishable even by people who do need glasses (maybe you should get your vision checked). It's been suggested that the only-the-people-with-the-sharpest-vision thing is actually referring to another, dimmer star that appears between Mizar and Alcor and WOULD require exceptional vision to see.
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You havent reached whatever comes after middle age then. I have trouble splitting them in a city now, but cant tell whether its because of the city lights or because my eyes are shot. They look great through a 10" dobsonian in any case :-)
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In ancient times the atmosphere was cleaner than now, and had a lot less light pollution from towns. Yet it apparently took "exceptional vision" to see Alcor and Mizar as separate stars. I must have phenomenal eyesight then to be able see them any night it isn't cloudy.
By ancient standards, you probably do. Especially if you have it without the use of corrective lenses that weren't available in ancient times.
Nearest sextuplet (Score:5, Informative)
In case anyone was wondering (and since TFA doesn't mention it), the nearest sextuplet star, is, of course, Alpha Geminorum [wikipedia.org], a.k.a. Castor, the second-brightest star in the zodiac sign of Gemini [wikipedia.org], a.k.a. the Twins. It's some 50-odd lightyears away.
Note that Beta Geminorum [wikipedia.org], a.k.a. Pollux, is actually the brightest star in Gemini (whether Johann Bayer [wikipedia.org] labelled Castor as the alpha star because it rises first in the night's sky, or because mythologically, the twins are always labelled "Castor and Pollux", is unknown). Pollux is a single star, with one confirmed exoplanet, Polydeuces [wikipedia.org] orbitting it.
Nightfall (Score:5, Interesting)
I couldn't help but think of Asimov's story, Nightfall. In it, a planet is in a 6-star system and is never dark. Interesting things happen.
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It is almost never dark.
Whoops, should have warned about that spoiler, hey?
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Man, you couldn't blown that more than if you'd put the spoiler in the title of the book.
WTF? (Score:2)
So you are telling me that this system now has 6 suns instead of 4?
I think this calls for George Lucas to redo all the star wars movies YET AGAIN, with
a new backdrop featuring the 6 suns, as it could very well be a cooler movie with 6 instead of 2!!!
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Astrobooboos (Score:3, Insightful)
Alcor is not one of the brightest stars in the Big Dipper. It is a dim double with Mizar. We usually consider the dipper to have 7 stars: 4 in the 'pot' and three in the handle. Mizar is the center of the handle. Alcor is so close to Mizar and relatively dim that it's not even considered a point in the constellation.
Not incorrect but misleading, Castelli was the first to see it as a double 'with a telescope'. The names themselves being Arabic, should be a tip off. Would Alcor have an Arabic name if they didn't see it? They are a visual double, not requiring a telescope to see if one has good vision (as opposed to an optical double, being line of sight but not necessarily naked eye). Such as noted by the Arabic chroniclers of astronomy, as well as the Native Americans who saw the bowl of the dipper as the bear, and the three stars in the handle as three bear cubs or some as three hunters (or sever, per the Mikmac) following the bear. All knew of the two stars. Sir Patrick Moore suggests the early writings refer to Mizar A and B instead, and gives good logical thinking, though I know of pre-tlescope maps of Mizar and Alcor, but not Mizar A and B,
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Resolving Mizar A and B (14 arcsecond separation) exceeds the theoretical resolving power of the human eye, and even with perfect vision your eye can't come close to that limit in the dark because your pupil dilates.
Sir Patrick Moore suggests that the reference is to splitting Mizar and a dim star that appears between Mizar and Alcor.
This raises a question (Score:2)
How close? Doesn't matter. (Score:1)
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Isn't every star in the galaxy ultimately rotating around every other star in the galaxy?
No. Every star in the universe is gravitationally affected by every other star in the universe, but none are known to actually revolve around all the others (and none rotate around anything but their own axis).
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