A multiple star system consists of three or more stars.
Such a system is a multiple-star system. If it contains exactly two stars then it is called a binary system.
Nazil's system
A system composed of more than two stars is called a multiple star system. This can include triple star systems (trinaries), quadruple star systems (quadrinaries), or even more complex configurations with numerous stars orbiting each other.
Mizar is a quadruple or quaternary star system. When there is more than two stars, it is called a star system or multiple star system or stellar system. Depending on the number of stars, they are also called a triple, quadruple or quintuple star system or trinary, ternary, quaternary, quintenary, sextuple, sextenary, septuple or septenary star system.
Astronomers
Astronomers
Astronomers
Mainly astronomers. But cosmologists and astrophysicists will also be interested in outer space.
In ancient Egypt their astronomers use the stars to predict when the Nile River would flood.
An astronomer, they studied the stars and so do modern astronomers, why should there be any difference in naming? Aristotle was a philosopher.
Either a Kuiper Belt Object (KBO) or something in the Oort cloud. There are a LOT of things past Neptune - Stars, galaxies, exoplanets.......
One. We call it "The Sun".