Telescope Nerd » How To See » How to See Binary Stars With A Telescope?

How to See Binary Stars With A Telescope?

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.

What are Binary Stars?

Binary stars are a type of star system where two stars orbit around a common center of mass due to their mutual gravitational attraction. They can be detected through various methods, such as observing their visual, spectroscopic, or astrometric properties. Visual binaries are identified by directly observing two distinct stars, while spectroscopic binaries are detected by analyzing periodic Doppler shifts in their spectral lines. Astrometric binaries are identified by observing a star’s periodic “wobble” caused by the gravitational influence of an unseen companion. The evolution of binary star systems can be influenced by factors such as the mass ratio of the two stars, their separation, and their orbital period. These factors can lead to phenomena like mass transfer, energy exchange, and even mergers between the two stars. Eclipsing binary stars are a subcategory of binary stars where the two stars’ orbits are aligned in such a way that they periodically eclipse each other from our line of sight. These systems provide valuable information for calculating stellar masses and refining mass-luminosity relations, as well as testing theoretical models of stellar structure and evolution. Binary star systems can be classified based on the distance between the stars relative to their sizes. This classification helps in understanding the interaction between the two stars and their evolution. The study of binary stars is essential for determining individual stellar masses and understanding the formation and evolution of star systems. Precise astrometry techniques, including interferometric observing methods and high-precision photometry, are employed to accurately measure the positions and motions of binary stars.

How far are Binary Stars from planet Earth?

The average distance between binary stars and Earth can range from 380,000 km to 4.25 light-years, while the average distance between stars in a binary star system can range from a few astronomical units (AU) to several light-years. The minimum distance between stars in a binary star system can range from a few astronomical units to over 100 astronomical units.

Can you see Binary Stars with a telescope?

Yes, binary stars can be observed with a telescope. Some of the stars in the sky are double or multiple, and many of them can be visually resolved through a telescope, which reveals them as two or more dots placed closely together. A small, cheap telescope allows to observe plenty of doubles, however a larger and more quality instrument will allow to resolve tighter pairs, and provide more visually appealing image. The optical quality of binary stars when viewed through a telescope can be affected by factors such as the type of binary star (optical, visual, or non-visual), the distance between the two stars, and the presence of a dense disk or envelope of dust surrounding the stars. The brightness of the primary star in a binary star system can vary depending on the specific characteristics of the system, with some primary stars being significantly brighter than their companion stars. Factors that affect atmospheric steadiness when observing binary stars with a telescope include the brightness of the stars, the distance between the stars, and the presence of any additional objects in the field of view. The best time to observe binary stars is during clear nights with steady atmospheric conditions, away from city lights to avoid light pollution.

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?

  1. Point the scope towards Binary Stars and center it in the finder.
  2. 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.
  3. 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
ObjectConstellationMagnification (Recommended)Right AscensionDeclinationMagnitudesSeparation
Xi (Ξ)Boötes50x14 h 51.4 m·19° 06′4.7, 7.07″
Epsilon (ε)Boötes100x14 h 45.0 m·27° 04′2.5,4.93″
Zeta (Ζ)Cancer50x8 h 12.2 m·17° 39′5.6, 6.06″
Iota ΙCancer15x8 h 46.7 m·28° 46′4.2, 6.630″
Alpha (α) CentauriCentaurus·25x14 h 39.6 m·-60° 50′0.0, 1.414″
Cor Caroli (α)Canes Venatici25x12 h 56.0 m·38° 19′2.9, 5.519″
Gamma (γ)Leo100x10 h 20.0 m·19° 51′2.2, 3.54″
Acrux (Α)Crux·100x12 h 26.6 m·-63° 06′1.4, 1.94″
Porrima (Γ)Virgo100x12 h 41.7 m·-01° 27′3.5, 3.54″
Mizar (Ζ)Ursa Major25x13 h 23.9 m·54° 56′2.3, 4.014″
Summer’s double stars
ObjectConstellationMagnification (Recommended)Right AscensionDeclinationMagnitudesSeparation
Alpha (α)Capricornus7x20 h 18.1 m·-12° 33′3.6, 4.2378″
Albireo (Β)Cygnus25x19 h 30.7 m·27° 58′3.1, 5.134″
Beta (β)Capricornus7x20 h 21.0 m·-14° 47′3.4, 6.2206″
61Cygnus25x21 h 06.9 m·38° 45′5.2, 6.028″
Gamma (γ)Delphinus25x20 h 46.7 m·16° 07′4.5, 5.510″
Omicron (ο)Cygnus10x20 h 13.6 m·46° 44′3.8, 4.8, 6.7338″, 107″
Alpha (α)HerculisHercules100x17 h 14.6 m·14° 23′3.5, 5.45″
Nu (ν)Draco7x17 h 32.2 m·55° 11′4.9, 4.962″
Double-Double (ε)Lyra7x, 100x18 h 44.3 m·39° 40′5.0, 6.1,5.2, 5.5208″, 2″,2″
Delta (δ)Hercules50x17 h 15.0 m·24° 50′3.1, 8.29″
Autumn’s double stars
ObjectConstellationMagnification (Recommended)Right Ascension.DeclinationMagnitudesSeparation
Gamma (γ)Andromeda50x2 h 03.9 m·42° 20′2.3, 5.510″
Gamma (γ)Aries·50x1 h 53.5 m·19° 18′4.8, 4.88″
Zeta (ζ)Aquarius100x22 h 28.8 m·-00° 01′4.3, 4.52″
Eta (η)Cassiopeia50x0· h 49.1 m·57° 49′3.4, 7.512″
Lambda (λ)Aries·25x1h57.923° 36′4.9, 7.737″
32Eridanus50x3 h 54.3 m·-02° 57′4.8, 6.17″
Sigma (σ)Cassiopeia100x23 h 59.0 m·55° 45′5.0, 7.13″
Iota (ι)Triangulum50x2 h 12.4 m·30° 18′5.3, 6.94″
Eta (η)Perseus50x2 h 50.7 m·55° 54′3.8, 8.528″
Polaris (Α)Ursa Minor50x2 h 31.8 m·89° 16′2.0, 9.018″
Winter’s double stars
ObjectConstellationMagnification (Recommended)Right Ascension.DeclinationMagnitudesSeparation
h3945Canis Major50x7 h 16.6 m·-23 194.8, 6.827″
Castor (α)Gemini100x7 h 34.6 m·31° 53′1.9, 2.92″
Gamma (γ)Lepus7x5 h 44.5 m·-22° 27′3.7, 6.396″
Beta (β)Monoceros50x6 h 28.8 m·-07° 02′4.7, 5.27″
Theta (θ)Taurusnaked eye (in Hyades)4 h 28.7 m·15 523.4, 3.8300″
Mintaka (δ)Orion10x5 h 32.0 m·-00° 18′2.2, 6.353″
Lambda (λ)Orion100x5 h 35.1 m·09° 56′3.6, 5.54″
Sigma (σ)Orion50x5 h 38.7 m·-02° 36′4.0, 7.5,6.513″,43″
Rigel (Β)Orion100x5 h 14.5 m·-08° 12′0.1, 6.810″
Trapezium (θ-1)Orion100x5 h 35.3 m·-05° 23′6.7, 7.9,5.1, 6.79″, 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’.

Similar Posts