Che ne dite di dare la caccia a qualche doppia?
di Marco Bruno
Prendendo spunto dal noto sito theskyscrapers.org/spring-double-stars, ho rieditato la lista di alcune doppie da provare
Zeta Cancri magnitudes 5.6, 5.9, and 6.0, separations 1.0 and 6.0 arcseconds
A grand triple that requires a 6-inch scope and steady seeing to resolve the closest components
213° 63°
Phi2 Cancri mags 6.3 and 6.3, sep 5.2″
Pretty twin system, located about 10 degrees east of Pollux.
237° 62°
Iota Cancri mags 4.2 and 6.6, sep 30.5″
A springtime “Albireo,” with striking gold and blue colors.
232° 66°
Alpha Leonis (Regulus) mags 1.3 and 7.6, sep 176″
Despite their wide separation, these two stars share a common proper motion. Like the similar pair epsilon Pegasi, this duo displays an illusory oscillating motion when you jiggle the telescope tube back and forth in a direction perpendicular to a line joining them.
180* 56*
Gamma Leonis (Algeiba) mags 2.6 and 3.8, sep 4.5″
Beautiful slow-moving binary; both yellow.
174° 64°
xi Ursae Majoris mags 4.3 and 4.8, sep 1.6″
A rapidly-moving binary system with a period of about 60 years. A good test for a 3-inch scope.
17° 45°
N Hydrae mags 5.8 and 5.9, sep 9.1″
Observers in northerly latitudes usually don’t see this beautifully matched pair at its best.
169° 28°
Wnc 4 Ursae Majoris mags 9.0 and 9.3, sep 50″
What is so faint and wide a pair doing on this list? Simple it’s a Messier object! Unable to find a nebulous object reported to be in the area, the great comet hunter found this dim pair and (for reasons we can only guess) assigned it as his 40th object.
45° 66°
Alpha Canum Venaticorum (Cor Caroli) mags 2.9 and 5.4, sep 19,6″
One of the finest double stars in the sky for small telescopes. Colors have been described as white and slightly yellowish. What do you see?
87° 58°
Zeta Ursae Majoris (Mizar) mags 2.4 and 4.0, sep 14.4″
The first telescopic double discovered (Riccioli 1650). Like Cor Caroli, one of the finest pairs for small telescopes. Forms a naked eye pair with 4th magnitude Alcor, located 12′ to the east.
54° 58°