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Periastron is the closest approach between two astronomical bodies. This is similar to the terms "perigee" and "perihelion" which refer to the closest approach to earth, and the sun respectively.
The "angular" periastron refers to the smallest observed angle between two bodies. This distinction is important because of the difficulties in determining stellar distances in astronomy.
When we look at two stars, we can't really tell their distance. But over time we may see them circle around eachother. This means that the smallest angular seperation between the two, from our perspective, may have little relation to their physical distance.
The extreme case, to help illustrate the point, is if the two stars are orbiting in such a way as to be completely "edge on" relative to us. We see them only go left and right, they don't move in little circles. If this is the case then at some point the two stars will actually overlap, with one obscuring the other in an eclipse.
In this case of an eclipse, there is zero angular separation between the two, their "angular periastron" is zero. But this doesn't tell us how close the stars really are.
Looking at other binary stars, the greater the incline of the orbit (the more of a "top down" perspective we get) the more the angular periastron is related to the stars actual separation distance.
What else can I help you with?
How the angular velocity of binary stars are calculated?
By observation. The angular velocity can be derived from the period. If, for example, it takes a day (86,400 seconds) for a full revolution, then the angular velocity will be (2 x pi / 86400) radians per second.
Stars that are found in pairs are called?
Two stars orbiting each other are "binary stars" ...a group of stars near each other, may be formally or informally known as a "cluster".
What colors are binary stars?
Binary stars can be any color that stars can be. There's no need for the two stars in a binary to be the same color.
What percentage of stars are binary stars?
Roughly half of all stars in the galaxy are estimated to be part of binary or multiple star systems. This means approximately 50% of stars are binary stars.
What are two stars bound by gravity called?
Binary stars
Suppose the angular separation of two stars is samller than the angular resolution of your eyes How will the stars appear to your eyes?
If the angular separation of two stars is smaller than the angular resolution of your eyes, they will appear as a single point of light rather than two distinct stars. This is due to the limit of your eyes' ability to resolve fine details at such a close angular distance.
How many stars make up binary star?
By definition, a binary star system has two stars in it.
How is a binary used?
Binary what? Binary numbers? Binary stars? Binary fission?
To calculate the mass of a star scientists study?
the orbits of binary stars
What do the orbits of binary stars tell about stars?
Binary stars are very useful for determining the mass of the stars and thus any objects orbiting around them.
What is a binary protostar?
"Binary" means there are two stars. And "protostar" means the stars are in an early, or preliminary, stage.
How do binary stars differ form the supernovas and novas?
binary stars are two stars that orbit each other while supernovas and novas stars are stars that explode when it runs out of fuel
