Telescope has revealed the interesting fact that all stars are not alone. Sometimes they are accompanied by one or other multiple stars and form star systems. Double stars that are bound gravitationally are called binary star systems. According to the research around 85% of the stars of the Milky Way are in binary pairs unlike our Sun and no two binary stars are similar. However, several binary systems are visible through telescopes.
Quick Guide to Observe Binary Stars
Make sure you have a star map before you begin. Center the scope in the finder and aim it at Binary Stars. For a closer look, choose the eyepiece with the lowest power and highest focal length. A 20 mm eyepiece or Barlow lens, for instance, will perform better in this situation. Check the finder scope’s alignment if you are unable to locate Binary Stars. Check your focus after you’ve located Binary Stars. A 4-inch telescope that can divide stars up to 1.15 arcseconds apart can see binary stars. Start by using a 50x magnification.
Before starting, make sure you have a star map.
Without a star chart or stargazing app, it is not possible to differentiate whether the double stars are optical doubles (being in a close location but with no gravitational attachment) or a binary system. You can go through “See it With a Small Telescope” which offers a constellation chart made by the International Astronomical Union and Sky & Telescope Magazine. They use the size of the dots to indicate the magnitude of the dots. You also can use different star apps like Stellarium, SkySafari, etc.
How to find Binary Stars?
- Point the scope towards Binary Stars and center it in the finder.
- Use the lowest power eyepiece with the highest focal length for a closer look. For example, a 20 mm eyepiece or Barlow lens will work better in this. If you cannot find Binary Stars then check the alignment of the finder scope.
- After you find Binary Stars, check your focus.
What is the best time to observe Binary Stars?
To find out the best time of Binary Stars observation make sure to check the tables below:
| Spring’s double stars | ||||||
| Object | Constellation | Magnification (Recommended) | Right Ascension | Declination | Magnitudes | Separation |
| Xi (Ξ) | Boötes | 50x | 14 h 51.4 m· | 19° 06′ | 4.7, 7.0 | 7″ |
| Epsilon (ε) | Boötes | 100x | 14 h 45.0 m· | 27° 04′ | 2.5,4.9 | 3″ |
| Zeta (Ζ) | Cancer | 50x | 8 h 12.2 m· | 17° 39′ | 5.6, 6.0 | 6″ |
| Iota Ι | Cancer | 15x | 8 h 46.7 m· | 28° 46′ | 4.2, 6.6 | 30″ |
| Alpha (α) Centauri | Centaurus· | 25x | 14 h 39.6 m· | -60° 50′ | 0.0, 1.4 | 14″ |
| Cor Caroli (α) | Canes Venatici | 25x | 12 h 56.0 m· | 38° 19′ | 2.9, 5.5 | 19″ |
| Gamma (γ) | Leo | 100x | 10 h 20.0 m· | 19° 51′ | 2.2, 3.5 | 4″ |
| Acrux (Α) | Crux· | 100x | 12 h 26.6 m· | -63° 06′ | 1.4, 1.9 | 4″ |
| Porrima (Γ) | Virgo | 100x | 12 h 41.7 m· | -01° 27′ | 3.5, 3.5 | 4″ |
| Mizar (Ζ) | Ursa Major | 25x | 13 h 23.9 m· | 54° 56′ | 2.3, 4.0 | 14″ |
| Summer’s double stars | ||||||
| Object | Constellation | Magnification (Recommended) | Right Ascension | Declination | Magnitudes | Separation |
| Alpha (α) | Capricornus | 7x | 20 h 18.1 m· | -12° 33′ | 3.6, 4.2 | 378″ |
| Albireo (Β) | Cygnus | 25x | 19 h 30.7 m· | 27° 58′ | 3.1, 5.1 | 34″ |
| Beta (β) | Capricornus | 7x | 20 h 21.0 m· | -14° 47′ | 3.4, 6.2 | 206″ |
| 61 | Cygnus | 25x | 21 h 06.9 m· | 38° 45′ | 5.2, 6.0 | 28″ |
| Gamma (γ) | Delphinus | 25x | 20 h 46.7 m· | 16° 07′ | 4.5, 5.5 | 10″ |
| Omicron (ο) | Cygnus | 10x | 20 h 13.6 m· | 46° 44′ | 3.8, 4.8, 6.7 | 338″, 107″ |
| Alpha (α)Herculis | Hercules | 100x | 17 h 14.6 m· | 14° 23′ | 3.5, 5.4 | 5″ |
| Nu (ν) | Draco | 7x | 17 h 32.2 m· | 55° 11′ | 4.9, 4.9 | 62″ |
| Double-Double (ε) | Lyra | 7x, 100x | 18 h 44.3 m· | 39° 40′ | 5.0, 6.1,5.2, 5.5 | 208″, 2″,2″ |
| Delta (δ) | Hercules | 50x | 17 h 15.0 m· | 24° 50′ | 3.1, 8.2 | 9″ |
| Autumn’s double stars | ||||||
| Object | Constellation | Magnification (Recommended) | Right Ascension. | Declination | Magnitudes | Separation |
| Gamma (γ) | Andromeda | 50x | 2 h 03.9 m· | 42° 20′ | 2.3, 5.5 | 10″ |
| Gamma (γ) | Aries· | 50x | 1 h 53.5 m· | 19° 18′ | 4.8, 4.8 | 8″ |
| Zeta (ζ) | Aquarius | 100x | 22 h 28.8 m· | -00° 01′ | 4.3, 4.5 | 2″ |
| Eta (η) | Cassiopeia | 50x | 0· h 49.1 m· | 57° 49′ | 3.4, 7.5 | 12″ |
| Lambda (λ) | Aries· | 25x | 1h57.9 | 23° 36′ | 4.9, 7.7 | 37″ |
| 32 | Eridanus | 50x | 3 h 54.3 m· | -02° 57′ | 4.8, 6.1 | 7″ |
| Sigma (σ) | Cassiopeia | 100x | 23 h 59.0 m· | 55° 45′ | 5.0, 7.1 | 3″ |
| Iota (ι) | Triangulum | 50x | 2 h 12.4 m· | 30° 18′ | 5.3, 6.9 | 4″ |
| Eta (η) | Perseus | 50x | 2 h 50.7 m· | 55° 54′ | 3.8, 8.5 | 28″ |
| Polaris (Α) | Ursa Minor | 50x | 2 h 31.8 m· | 89° 16′ | 2.0, 9.0 | 18″ |
| Winter’s double stars | ||||||
| Object | Constellation | Magnification (Recommended) | Right Ascension. | Declination | Magnitudes | Separation |
| h3945 | Canis Major | 50x | 7 h 16.6 m· | -23 19 | 4.8, 6.8 | 27″ |
| Castor (α) | Gemini | 100x | 7 h 34.6 m· | 31° 53′ | 1.9, 2.9 | 2″ |
| Gamma (γ) | Lepus | 7x | 5 h 44.5 m· | -22° 27′ | 3.7, 6.3 | 96″ |
| Beta (β) | Monoceros | 50x | 6 h 28.8 m· | -07° 02′ | 4.7, 5.2 | 7″ |
| Theta (θ) | Taurus | naked eye (in Hyades) | 4 h 28.7 m· | 15 52 | 3.4, 3.8 | 300″ |
| Mintaka (δ) | Orion | 10x | 5 h 32.0 m· | -00° 18′ | 2.2, 6.3 | 53″ |
| Lambda (λ) | Orion | 100x | 5 h 35.1 m· | 09° 56′ | 3.6, 5.5 | 4″ |
| Sigma (σ) | Orion | 50x | 5 h 38.7 m· | -02° 36′ | 4.0, 7.5,6.5 | 13″,43″ |
| Rigel (Β) | Orion | 100x | 5 h 14.5 m· | -08° 12′ | 0.1, 6.8 | 10″ |
| Trapezium (θ-1) | Orion | 100x | 5 h 35.3 m· | -05° 23′ | 6.7, 7.9,5.1, 6.7 | 9″, 13″,22″ |
3 Tips to observe Binary Stars in the best way.
- Choose a night when the air is tranquil or free of disturbance. The motion in different layers of air makes the star twinkle and the image shaky. You might not be able to split the binary pair to see them individually due to the shake.
- If the binary star is on the horizon, you have to look through the thick layer of atmosphere that may cause distortion or make them look like a single star. Try to observe the binary stars that are located overhead near the zenith.
- Make sure the sky is dark enough to avoid light pollution.
Which Binary Stars can be seen with a telescope?
- Lyra is a binary star system 960 light years away from our solar system. Lyra is best seen in Summer.
- Eta Cassiopeiae is located in the northern constellation of Cassiopeia. A 10-inch telescope is needed to see its off-white and reddish-orange stars.
- ALMACH or Gamma1 Andromedae shows its Yellow (Gold) and light blue stars with a 10-inch telescope.
- h 3945 binary system includes ADS 5951, CMA that can be seen by a 10-inch telescope with their light yellow and pale blue color.
- Lota Cancri appears in a 10-inch telescope with separate yellow and pale blue stars.
- 24 Comae Berenices comes up with its Yellow and pale· blue color stars in a 10-inch telescope.
- Antares (Alpha Sco) includes orange and light blue stars.
- Ras Algethi (Alpha Her) appears with its reddish-orange and pale bluish-white stars in a 10-inch aperture.
What telescope to see Binary Stars?
The Meade 10″ ACF LX90 Telescope, Celestron – NexStar 8SE – Computerized Telescope, and Orion 09007 SpaceProbe 130ST Equatorial Reflector are great telescopes to see Binary Stars. A list of telescopes to see Binary Stars has more telescope options that can see Binary Stars very clearly.
What size telescope to see Binary Stars?
Binary stars are visible with a 4-inch telescope that can split the stars highest 1.15 arcseconds apart. 8 inch telescopes are great to see the binary stars with the other objects nearby. The 10-inch telescope can reveal the natural colors of most binary stars.
What magnification is required to see Binary Stars?
Try with a 50x magnification at first. If you can not split the stars with this magnification, increase it to 75x-100x. 100x magnification is enough to show the stars with their color and separation.
Enjoying Binary Stars? Here are other things to see with your telescope.
There are a lot of binary stars visible with telescopes. The same telescope can show you other stars, galaxies, and nebulae in the night sky. The planets of the solar system might appear with their amazing views and color. Even the sun with proper protection comes up with a fantastic look. Viewing Meteor Shower Through A Telescope can guide you to observe meteor showers with your telescope. Moreover, you can get a list of observable night sky objects by going through ‘List of things to see with a telescope’.