noun
dwarf galaxy
Technical term in astronomy for a small galaxy with relatively few stars.
天の川銀河の周りには、いくつかの矮小銀河が存在する。
Several dwarf galaxies exist around the Milky Way.
銀河 is a general term for any galaxy, while 矮小銀河 specifically refers to a dwarf galaxy, which is much smaller and less luminous.
Compound of 矮小 (わいしょう, 'diminutive, dwarf') and 銀河 (ぎんが, 'galaxy'). The term is a direct translation of the English 'dwarf galaxy'.