Double, multiple and special stars
by Jean Vallières
by Jean Vallières
Observation and photography of double and multiple stars is a project open to all amateur astronomers, even with modest instruments. Moreover, this type of project is virtually unaffected by light pollution as may be the pictures of deep sky objects.
The sight of two close stars of different colors remains a great show to watch. The best known example is Albireo (beta Cygni), but the sky is filled with dozens of other easily observed multiple stars.
All images were captured with a modified RCX400 telescope of 250 mm aperture and 2000 mm focal length, and with a small Celestron NexImage 5 Planetary Camera. The small 2.2 microns pixels of this camera have yielded a good resolution without requiring a barlow or eyepiece projection.
To properly represent the stellar pairs, the images are all at the same scale and measure for most 80 x 80 arcsec (slightly less than 2 times the apparent diameter of Jupiter). Each image is a combination of the eight best 1/15 s unitary shots (out of 80 to 160 frames), aligned and combined with Registax. I tried to process the images to reproduce as closely as possible the apparent observed colors, using PixInsight software and PhotoShop. The photo series was started in June 2012 and should be completed as conditions will allow. The celestial north is up (unless otherwise stated).
The stars shown can be observed until at least two months before and after the month indicated.
Click on the name of the star for a location map.
The sight of two close stars of different colors remains a great show to watch. The best known example is Albireo (beta Cygni), but the sky is filled with dozens of other easily observed multiple stars.
All images were captured with a modified RCX400 telescope of 250 mm aperture and 2000 mm focal length, and with a small Celestron NexImage 5 Planetary Camera. The small 2.2 microns pixels of this camera have yielded a good resolution without requiring a barlow or eyepiece projection.
To properly represent the stellar pairs, the images are all at the same scale and measure for most 80 x 80 arcsec (slightly less than 2 times the apparent diameter of Jupiter). Each image is a combination of the eight best 1/15 s unitary shots (out of 80 to 160 frames), aligned and combined with Registax. I tried to process the images to reproduce as closely as possible the apparent observed colors, using PixInsight software and PhotoShop. The photo series was started in June 2012 and should be completed as conditions will allow. The celestial north is up (unless otherwise stated).
The stars shown can be observed until at least two months before and after the month indicated.
Click on the name of the star for a location map.
| NAME 1 | NAME 2 | Note | R.A. 2000.0 | Decl. 2000.0 | Magn. 1 | Magn. 2 | Separation | (B-V) 1 | (B-V) 2 | Colors |
| mu Dra | 17h 05m 20.2s | +54° 28' 13" | 5.6 | 5.6 | 2.2" | 0.44 | 0.45 | yellow - yellow | ||
| alpha Her | Rasalgethi | 17h 14m 38.9s | +14° 23' 25" | 3,4 | 5.3 | 4.9" | 1.29 | 0.67 | orange - blue green | |
| rho Her | 17h 23m 41.0s | +37° 08' 45" | 4.5 | 5.4 | 4.1" | -0.02 | 0.00 | white - light blue | ||
| nu Dra | 17h 32m 10.6" | +55° 11' 03" | 4.9 | 4.9 | 62" | 0.25 | 0.28 | cream - cream | ||
| psi1 Dra | 17h 41m 56.3s | +72° 08' 58" | 4.6 | 5.7 | 30.3" | 0.39 | 0.49 | light yellow - yellow | ||
| 61 Oph | 17h 44m 34.1s | +02° 34' 46" | 6.1 | 6.5 | 20.6" | 0.08 | 0.06 | white - white | ||
| 95 Her | 18h 01m 30.4s | +21° 35' 45" | 4.9 | 5.1 | 6.4" | 0.11 | 0.86 |
light green - yellow orange |
||
| 70 Oph | 18h 05m 27.2s | +02° 30' 09" | 4.3 | 6.2 | 6" | yellow - orange | ||||
| 100 Her | 18h 07m 49.6s | +26° 06' 04" | 5.8 | 5.9 | 14" | 0.15 | 0.12 | white - white | ||
| epsilon1 Lyr | 1 | 18h 44m 20.4s | +39° 40' 12" | 5.0 | 6.0 | 2.6" | 0.12 | 0.28 | white - white | |
| epsilon2 Lyr | 1 | 18h 44m 22.8s | +39° 36' 45" | 5.2 | 5.4 | 2.3" | 0.17 | 0.21 | white - white | |
| zeta Lyr | 18h 44m 46.6s | +37° 36' 18" | 4.3 | 5.7 | 44" | 0.19 | 0.29 | white - cream | ||
| beta Lyr | Sheliak | 2 | 18h 50m 04.8s | +33° 21' 46" | 3.7 V | 6.7 | 46" | -0.10 | -0.03 | white - white |
| omicron Dra | 18h 51m 12.1s | +59° 23' 18" | 4.6 | 8.1 | 34.2" | 1.19 | 1.18 | yellow orange - green | ||
| theta Ser | 18h 56m 13.2s | +04° 12' 13" | 4.6 | 5.0 | 22.3" | 0.16 | 0.20 | white - white |
Notes:
1 : The third star, 16 Dra, of magn. 5.5, is 90" to the south of 17 Dra. Color light blue and (B-V) = -0.06.
1 : The third star, 16 Dra, of magn. 5.5, is 90" to the south of 17 Dra. Color light blue and (B-V) = -0.06.
| NAME 1 | NAME 2 | Note | R.A. 2000.0 | Decl. 2000.0 | Magn. 1 | Magn. 2 | Separation | (B-V) 1 | (B-V) 2 | Colors |
| kappa Boo | 14h 13m 29.0s | +51° 47' 24" | 4.5 | 6.6 | 13.6" | 0.19 | 0.35 | white - blue | ||
| ksi Boo | 14h 51m 23.3s | +19° 06' 02" | 4.7 | 6.8 | 6.9" | 0.70 | 1.16 | yellow - orange |
May
June
| NAME 1 | NAME 2 | Note | R.A. 2000.0 | Decl. 2000.0 | Magn. 1 | Magn. 2 | Separation | (B-V) 1 | (B-V) 2 | Colors |
| delta Ser | 15h 34m 48.2s | +10° 32' 20" | 4.1 | 5.1 | 3.9" | 0.24 | 0.24 | light yellow - light yellow | ||
| zeta CrB | 15h 39m 22.7" | +36° 38' 09" | 5.0 | 5.9 | 6.4" | -0.10 | -0.10 | light blue - green blue | ||
| kappa Her | 16h 08m 04.6s | +17° 02' 49" | 5.0 | 6.2 | 27" | 0.91 | 1.12 | yellow - orange | ||
| sigma CrB | 16h 14m 41.1s | +33° 51' 32" | 5.5 | 6.5 | 6.2" | 0.55 | 0.58 | yelloe - yellow | ||
| 17 Dra | 1 | 16h 36m 13.7s | +52° 55' 28" | 5.4 | 6.4 | 3.4" | -0.06 | 0.05 | light blue - white |
July
August
Notes:
1: Epsilon1 and epsilon2 themselves form a separate pair of 208 " that is called the Lyrae double-double.. Epsilon1 is the most northerly.
2: Beta Lyrae is an eclipsing variable star whose magnitude varies from 3.3 to 4.3 with a period of 12.94 days.
1: Epsilon1 and epsilon2 themselves form a separate pair of 208 " that is called the Lyrae double-double.. Epsilon1 is the most northerly.
2: Beta Lyrae is an eclipsing variable star whose magnitude varies from 3.3 to 4.3 with a period of 12.94 days.
Notes:
1: Struve 2470 and Struve 2474 form themselves a pair separated by 10.4 arc minutes and are known as the other double-double in Lyra. The difference with Epsilon Lyrae is that the stars are smaller but more separated and all of different colors.
2: The double star Albireo is the best known and most observed colored double star. The colors are visible even with binoculars.
1: Struve 2470 and Struve 2474 form themselves a pair separated by 10.4 arc minutes and are known as the other double-double in Lyra. The difference with Epsilon Lyrae is that the stars are smaller but more separated and all of different colors.
2: The double star Albireo is the best known and most observed colored double star. The colors are visible even with binoculars.
See also:
| NAME 1 | NAME 2 | Note | R.A. 2000.0 | Decl. 2000.0 | Magn. 1 | Magn. 2 | Separation | (B-V) 1 | (B-V) 2 | Colors |
| 15 Aql | 19h 04m 57.7s | -04° 01' 53" | 5.4 | 7.0 | 38" | 1.12 | 1.48 | yellow - yellow orange | ||
| Struve 2470 | SAO 67870 | 1 | 19h 08m 45.2s | +34° 45' 37" | 7.0 | 8.4 | 13.4" | -0.13 | 0.05 | blue - white |
| Struve 2474 | SAO 67879 | 1 | 19h 09m 04.4s | +34° 36' 00" | 6.7 | 8.0 | 16.2" | 0.61 | 0.73 | yellow - dark yellow |
| beta Cyg | Albireo | 2 | 19h 30m 43.3s | +27° 57' 35" | 3.4 | 5.5 | 34.4" | 1.09 | -0.10 | gold - blue |
| 16 Cyg | 19h 41m 49.0s | +50° 31' 30" | 6.0 | 6.3 | 39.6" | 0.64 | 0.66 | yellow - yellow | ||
| psi Cyg | 19h 55m 37.8s | +52° 26' 20" | 5.0 | 7.5 | 2.9" | 0.10 | 0.29 | white - white | ||
| 57 Aql | 19h 54m 37.7" | -08° 13' 38" | 5.7 | 6.5 | 35.5" | -0.08 | -0.04 | yellow - blue | ||
| 31 Cyg | 20h 13m 37.9s | +46° 44' 29" | 3.8 | 7.0 | 107" | 1.27 | -0.13 | yellow - blue | ||
| gamma Del | 20h 46m 39.5s | +16° 07' 27" | 4.2 | 5.0 | 9.0" | 1.00 | 0.53 | yellow - blue green |
September
| NAME 1 | NAME 2 | Note | R.A. 2000.0 | Decl. 2000.0 | Magn. 1 | Magn. 2 | Separation | (B-V) 1 | (B-V) 2 | Colors |
| 61 Cyg | 21h 06m 54.0s | +38° 44' 58" | 5.2 | 6.1 | 34.2" | 1.07 | 1.31 | orange - red | ||
| Struve 2816 (Cep) | 1 | 21h 38' 57.6" | +57° 29' 21" | 5.7 |
7.5 7.5 |
11.8" 20.1" |
0.15 |
0.18 0.15 |
all white | |
| mu Cyg | 21h 44m 08.6s | +28° 44' 34" | 4.7 | 6.1 | 1.8" | 0.41 | 0.52 | yellow - yellow | ||
| ksi Cep | 22h 03m 47.5" | +64° 37' 41" | 4.4 | 6.4 | 6.9" | 0.31 | 0.48 | yellow - yellow | ||
| delta Cep | 22h 29m 10.3s | +58° 24' 55" | 4.1 | 6.3 | 41" | 0.78 | -0.03 | yellow - blue purple | ||
| zeta Aqr | 22h 28m 49.9s | -00° 01' 12" | 4.3 | 4.5 | 2.2" | 0.38 | 0.34 | light yellow - yellow |
Notes :
1 : Struve 2816 is a triple star inside the nebula IC 1396.
1 : Struve 2816 is a triple star inside the nebula IC 1396.