Scorpius for the Big Dipper's Celebrated Duo
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DOUBLE STl•i.~S OF THE MJNTH by GZenn F. ChapZe, Jr. Southern sky objects tend to be ig- nored·b~observers in northerly latitu- des. Except for an occasional swipe at a Messier object, we usually bypass celestial objects that flirt with the treetops. When the results of last .year's "Top Ten Doubles" survey were tabulated, I was surprised to see the poor showing of BETA SCORPII (16h 02.5m; ,.: 190 40'), one of my favorites. The upper~ost of a graceful arc of bright stars that includes Scorpion members lIIU I1h':103 0 Delta and Pi, Beta (also called Akrab) ~.. o SETA is as attractive as it is easy to find. .H~:'~ BOME.(,A' Its resemblance to Mizar is more than o M'E,(,A 1 mere coincedence. The magnitudes (2.6 and 4.9) and separation (13.7") 6f its es member stars closely match the figures SCORPiUS for the Big Dipper's celebrated duo. Once you've captured Akrab in your tele- scope,look closely at the fainter com- ponent. ~t seems to sparkle with a dis- tinct blue or blue-green color that con- trasts nicely with the strong white light of the primary. Akrab isa quin- tuple star; the rest of the family is beyond the reach of small to medium-sized There is yet another multiple star in the telescopes. area! This is NU SCORPII (16h 09.1 m; -190 21'), a quadruple star situated a scant Almost 8~0 due· north of Akrab, at 16h degree-and-a-half east of Akrab. Small o 106m; - 110 14', are XI SCORPII and STRU- telescopes show a wide double whose magni- VE 1999, another quintuple system. Xi's tUde 4 and 6~ sparklers are 41 seconds apart. 4th magnitude leader is attended by a 7.2 Under the scrutiny of a 6-inch telescope, magnitude star, located 7.4 seconds away. the fainter star will yield components of A good 4-inch telescope, under ideal con- magnitudes 6.8 and 7.8, while a larger in- ditions, will split the primary into stars strument may be required to reveal the 6.4 of magnitudes 4.8 and 5.1. They complete magnitude sun that circles the primary. The an orbit once every 45.7 years, and only separations of these two pairs are 2.3" and recently passed their point of greatest 1.2", respectively, and the distance of the separation (1.25"). I first saw xi in entire system is over 400 light years. 1971, while surveying this region with my 3-inch reflector, and so saw it as a dou- If you own a standard 2.4-inch or blestar. In the same half-degree field, 3-inch refactor or 3-inch reflector, look a I found an unexpected bonus -- another degree west of Psi Ophiuchi and' you will dOUble star, and a real beauty, at that! find a "double-double" that is tailor-made Back indoors, I consulted Webb's CeZestiaZ for small 'scopes. Mexican amateur Juan G. ~bjeots for Common TeZesoopes, which Hernandez von W. brought this group to my ldentified the mystery double as Struve attention, and last May I checked it out 1999 (7.4+8.1; 11.4"). It is a travelling with my 3-inch reflector. I was not dis- companion of Xi, and completes this inter- appointed! Senor Hernandez' tip was a good esting quintet. At a distance of 80 light one -- the two pairs I encountered formed a years, the Xi-Struve system is almost truly beautiful sight. Burnham identifies eight times closer to earth than Akrab. the two as Sh225 (16h 17. 2m; -190 56 I; 7.0+ (Cont. on page 10) Deep Sky MonthZy, JulYJ 1979 * 11 (Continued from page 11) 8.S; 47.1") and Sh226 (16h 17.5m; -200 stars that are as far apart as Mizar and 00'; 7.S+8.0; 12.7"), while Webb re£erred Alcor. They show up well in binoculars, to them by using their John Herschel des- but are too wide to be attractive in the ignations of HhS03 and HhS04. Before telescope. leaving this part ofScorpius, stand back Next time you go out, turn your and survey it with the naked eye. You telescope away from the zenith and "ease should see a pretty pair of stars just it on down" toward the south. There's a below Beta. You are looking at OMEGA 1, lot of celestial beauty above those tree- OMEGA2 SCORPII, a set of 4th magnitude tops! 82 South Harbor' Rd~ TOUJnsend~ MA 01469 6.6~~.~.6.6.6.6.6.6.6.6.6.6.6.6.6.6.6.6.6.6.6.6.6.6.6.6.6.6.6.6.6.6.6.6.6.6.~.6.6.6.6.6.6.