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Big Dipper "Star" Actually a Sextuplet System
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."
Alcor, the star in question, is the middle star on the "handle" of the dipper.
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It just goes to show you that there's always something more to learn.
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You don't even need to RTFA - it is in the summary. Miza is a binary of binaries and Alcor is a binary. (2+2)+2=6. So you would not guess correctly.
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.
2*3*3*3*3*11*251
In case anyone was wondering (and since TFA doesn't mention it), the nearest sextuplet star, is, of course, Alpha Geminorum, a.k.a. Castor, the second-brightest star in the zodiac sign of Gemini, a.k.a. the Twins. It's some 50-odd lightyears away.
Note that Beta Geminorum, a.k.a. Pollux, is actually the brightest star in Gemini (whether Johann Bayer 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 orbitting it.
According to the link, the original source of the graph was http://nstars.nau.edu/nau_nstars/multi_search_start.php. From here it is possible to do a search by distance and have stars within a range returned. Searching for the range of 0 to 24.53 parsecs gave 2539 results. Also, the other sextuplet system that is closer is somewehre around 50 lightyears away.
He effected a bored affect.
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).
The chart has a linear regression line fit to it, and it seems like a decent fit line. So we might take the equation for the number of stars at a certain radius (let's call it stars_on_sphere(R) function) would be:
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 within 80 light years.
whoot, 2600!