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My 20 favorite double and multiple stars, part 3: summer
8. Delta 1 and 2 Lyrae (double star)
Constellation Lyra (Lyre), magnitude 5.6 / 4.2, separation 630”, position angle 243°, RA 18h54m DEC +36°55’. Lyra is, like Bootes and Corona Borealis, a treasure trove for observers of double and multiple stars. Delta 1 and 2 Lyrae are a very wide pair of stars that can be observed with handheld binoculars, and in my 15x80 binoculars (mounted on a mirror mount) I can see a bluish-white delta 1 Lyrae and an orange delta 2 Lyrae surrounded by 10 ten fainter stars, forming a star cluster called Stephenson 1. I love to look at this, 16’ wide, open cluster using my 4-inch refractor. At a magnification of 80x to 100x I see about 15 stars. Delta 1 Lyrae and Delta 2 Lyrae are true physical members of this small open cluster.

9. the Double Double (Epsilon 1, and 2 Lyrae, quadruple star)
Constellation Lyra (Lyre), magnitude AB 5.4 / 6.5 and CD 5.1 / 5.3, separation AB 2.6” and CD 2.3”, position angle AB 357° and CD 94°, RA 18h44m DEC +39°40’. The Double Double was the first double/multiple star system I observed with my 8-inch Klevtzov in 2001, and until now the views I got that particular night were the best I ever got from this celestial gem. It was late in august and it had been a very hot and humid day. Around midnight, the outdoor temperature was still above 20 degrees Celsius. There was absolutely no wind and during the daytime, the sky had looked milky-white. During the evening, the air felt heavy and around midnight, the night-sky looked hazy, somehow covered in high cirrus clouds. It seemed useless to get the equipment out for observing, but I just got my new telescope and I couldn’t wait to give it a try. When I pointed the 8-inch TAL at the Double Double, I was stunned by the view. At 166x I saw four bright white stars, of almost equal magnitude, grouped in pairs, two by two. The image looked like the stars where frozen in their position. There was absolutely no movement, no shimmering stars. Both doubles were split perfectly. Later I realized that for observing close double stars, the conditions must have been nearly perfect that night. I observed the Double Double again and again over the last few years, but I never managed to get the same wonderful views I got on that hot night in august 2001.

10. Albireo (Beta Cygni, double star)
Constellation Cygnus (Swan), magnitude 3.1 / 5.1, separation 34”, position angle 54°, RA 19h31m DEC 27°58’. In 1978 I followed a course “Astronomy for beginners” at the local astronomy club. The course started in the last week of august and after every lesson, we would go outdoors and look at a few objects through a 4.5-inch reflector. I remember looking at the Andromeda Galaxy, the Double Cluster in Perseus, M13 and ………. Albireo. Until then I had never seen a double star through a telescope, let alone a colored double star! Ever since, I have been looking at Albireo on every possible occasion, with all binoculars and telescopes I ever owned, and I still love to observe this simply beautiful object, even after all these years. Through my 8-inch at 66x the primary, a type-K star, looks golden or yellow. The secondary, a type-B star, looks blue. The contrast, color and brightness of both stars is striking, and this magical double star should be at the top of everyone’s observing list. It is one of the easiest doubles to find and, for me personally, the most beautiful to look at.

11. Omicron 1 and 2 Cygni (31 and 32 Cygni, multiple star for binoculars)
Constellation Cynus (Swan), magnitude 3.9 / 3.9, separation 1°, RA 13h6m DEC +46°44’ (coordinates for Omicron 1). Now this is my favorite multiple star (or group of stars) for binoculars. Through my 15x80, Omicron 1 and 2 Cygni look like two bright orange stars, separated about 1° from each other and of almost equal magnitude. Omicron 1 (31) Cygni is a visual triple itself. About 5’ to 6’ away to the northwest of the orange primary, at a position angle of 323°, I see a bluish (magnitude 4.8) companion and about 100” to the south I see a white (magnitude 6) star at a position angle of 173°. Together, Omicron 1 and 2 Cygni form a wonderful group of four stars to observe with binoculars.

12. 61 Cygni (Struve 2758, double star)
Constellation Cygnus (Swan), magnitude 5.2 / 6.1, separation 30”, position angle 150°, RA 21h07m DEC +38°45’. This is a wide double, which can be separated even in small telescopes and binoculars. Because of their more or less equal brightness, I managed to split 61 Cygni with my 7x50 Bresser mounted on a mirror mount. I never managed to split Albireo in my 7x50, although the angular separation of Albireo is wider (34”), than from 61 Cygni. This is probably caused by the magnitude difference. While Albireo’s components differ about two magnitudes, the brighter A component overpowering the fainter B component, the difference between the 61 Cygni components is only 0.8 magnitude, making it easier to “see” both the primary and secondary as separate stars at low powers. In my 15x80 both the primary and secondary of 61 Cygni look chrome-orange, with a hint of red. Again another celestial gem that shouldn’t be missed!

image

Image from SkyTools2 by Capellasoft, click to enlarge!
Posted by Math on 05/20 at 10:33 AM
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