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GRAFFIAS (Beta Scorpii). Graffias, in the head of the celestial Scorpion andScorpius's Beta star, has at least two namesand many more components. "Graffias," meaning "claws," originallyreferred to the "real" claws that are now inLibra,Zubenelgenubi andZubeneschamali. But in more modern timesthe name was given first -- and unaccountably -- to obscure XiScorpii and then to our star, Beta Scorpii. An equally common nameis "Acrab," from Arabic, meaning "the scorpion," older ideasstrongly relating crabs with scorpions. Though bright, just at theend of second magnitude, Graffias is still only the sixth brighteststar in this brilliant constellation, the Beta designation probablya result of the star's prominent position. It is wonderfullycomplex. Through a small telescope we see a classic double star,the components 14 seconds of arc apart, similar to the separationof those that makeMizar in the BigDipper. The brighter and more westerly, Beta-1, is just over theline into third magnitude (2.62), the fainter, Beta-2, is mid-fifthmagnitude (4.92). At a distance of 530 light years, the two are at least2200 astronomical units apart and take over 16,000 years to orbiteach other. Both are hot class B stars, Beta-1 the hotter with atemperature of around 27,000 Kelvin, Beta-2 closer to 22,000. Though both should appear blue-white to the eye, the brightnessdifference makes them look different through the telescope, thefainter one seeming a bit ashen, rather yellowish. The fun beginswith closer examination. Beta-1 has a tenth magnitude closercompanion only half a second of arc (projected 80 astronomicalunits) away, so Graffias now seems triple. More, Beta-1 proper(the brighter) is a "spectroscopic binary," the spectrum showingtwo stars in orbit with a period of 6.8 days, the separation a mere0.001 seconds, 0.3 AU, closer than Mercury is from theSun. Still more, Beta-2 has a faintercompanion a tenth of a second away from it. Graffias is at leasta quintuple star, and there are suggestions of more pieces. Allfive except perhaps for the faint companion of Beta-2 are hot Bstars, vividly showing their propensity for multiple birth. Thebrightest, the chief star of the Beta-1 triple, is over 20,000 times the solar luminosity (after correction for interstellar dust absorption). What a sight it would be from an"earth" orbiting Beta-1 and its two companions, say at 150astronomical units where we could survive. We would have a tripleSun, and off in the distance the double Beta-2 would shine 50 timesbrighter than our full Moon. Both of the Beta-1 close pair areover 10 times as massive as the Sun, and both will probably explodesometime in the next few million years. Scorpius and itsneighboring constellations are filled with stars like these. Someof what we know of the system came from a rare occultation(covering) by Jupiter in 1971, Beta-2 by Jupiter's satellite Io.
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