Sirius is the name of a star(a.k.a the brightest star in the sky) and is also called the Dog Star.
Coincidence? I think not. Dog Star, and Sirius Black’s Patronus is a shaggy black dog.
And Arcturus is one of the two brightest stars in the sky. Arcturus. As in Regulus Arcturus Black.
Also Andromeda is a constellation, also the name of Tonks’ mother.
And Luna is Latin for ‘the moon’.
Now I have suddenly became interested in Astronomy.