At star parties, one of the most popular things to do is look for double stars. The presenter will typically point out Mizar and its fainter companion, Alcor, near the bend of the handle of the Big Dipper. Alternatively, during the summer months, telescopes are frequently oriented to Albireo in Cygnus, much to the joy of the audience members.
On the other hand, double stars are frequently overlooked by serious amateur astronomers today because they are less fascinated by deep-sky phenomena. It’s a pity, because double stars are not only lovely to look at, but they also present an interesting challenge that allows an observer to evaluate both their own abilities and the capabilities of their telescope.
Double stars were formerly the focus of both professional and amateur astronomers alike, and they have played a significant part in our knowledge of gravity as well as the galaxy in which we currently reside.
What are Double Stars?
A double star is a pair of stars that are locked together by the force of gravitation and spin around their shared center. Double stars may be found in the Milky Way and in other galaxies. It’s not unusual to see double stars in the sky.
The orbital period, which may be as short as a few minutes for pairings that are extremely close together or as long as hundreds of years for pairings that are very far apart, is determined by the distance between the stars.
There are also multiple stars, which are systems that consist of three or four stars rotating around one another in complicated paths. The constellation Lyra seems to be a double star, but when viewed through a telescope, each of its two components is shown to be a separate binary system.
It’s possible that, from our perspective, one star appears to be quite close to another star, but this is simply due to the fact that both stars happen to be in the same direction out into space as us. In point of fact, there is zero connection between any of these heavenly bodies.
When we gaze up into the night sky, everything appears to be at the same distance from us. Therefore, we have no way of knowing whether one of them is more distant than the other, since everything in the night sky appears to be at the same distance.
Because they are both the same distance from us and revolve around each other, the stars that make up a binary star system always appear to be at the same location. This is not a coincidence.
How to observe Double Stars?
The only direct approach that astronomers now have for determining the mass of stars is to observe the orbits of double stars.
It is possible for gas to move from one star to another in a process that is known as “mass transfer” when two stars are extremely close to one another. This causes the stars’ shapes to be warped as a result of their mutual gravitational pull.
Through the use of the telescope, a large number of double stars that once looked to be single stars have been discovered. However, when they are in such close proximity to one another, they can only be identified by the use of spectroscopy on the light that they emit.
The spectra of two stars are then observed, and the Doppler effect, which is present in both spectra, is used to determine the velocity of the stars. Spectroscopic binaries are the name given to these two-membered pairs.
The majority of the stars that we can see in the night sky are either double stars or even multiples of themselves. When viewed from Earth, a double star system may exhibit an eclipsing binary if and when one of the stars in the system is seen to temporarily block out the light of the other.
It is only possible to view double stars when the atmosphere of Earth is completely motionless. A star will waver and dance because there is a lot of motion occurring in the various layers of our environment. When this happens, astronomers will claim that the sight is bad.
An observer using a telescope may have a very difficult time “splitting” a binary pair into its two components on nights with poor viewing conditions. This “splitting” of the pair into its two parts is known as “separation.”
It’s possible that you’ll just see a single star. When you gaze toward the horizon, you are gazing through a denser layer of the atmosphere than when you gaze in any other direction. Therefore, when seeing double stars, it is preferable to have your focal point situated close to the zenith of the sky.