Function: noun
Date: 1785
: a usually compact luminous ring-shaped nebula that is composed of matter which has been ejected from a hot star at its center
Function: noun
Date: 1785
: a usually compact luminous ring-shaped nebula that is composed of matter which has been ejected from a hot star at its center
Merriam Webster Collegiate English Dictionary. Merriam Webster - Энциклопедический словарь английского языка. 2012