Protostar
A star that is forming is called a protostar.
Yes, a Lyman-break galaxy is a star forming galaxy at a high redshift.
Nebula.
The star is a polygon, but not a simple one. It is not simple because parts of the lines forming its boundaries are inside the star. The outline of a star is a simple polygon.
You can detect planets around are star only if they are of sufficient mass, They will cause the star to wobble (due to its gravity) as it rotates this can be seen and the position of the planet inferred.
Stars' are forming and dying all the time, as we speak.
It depends on the size of the star forming. For a one solar-mass star it lasts about 1,000,000 years.
For forming it is Heat of (Fusion) and for melting its Heat of (Vaporization).
cassiopeia
The star forming a group that has a recognisable shape is called a constellation.
cassiopeia
the name of a lucky star is a shooting star