▁and ▁a ▁star bur st ▁galax y . ▁I ▁Z wick y ▁ 1 8 ▁is ▁much ▁smaller ▁than ▁our ▁Mil ky ▁Way ▁and ▁a ▁mere ▁ 3 , 0 0 0 ▁light - year s ▁across . ▁I ▁Z wick y ▁ 1 8 ▁may ▁still ▁be ▁creating ▁Population ▁III ▁stars — spect ro sc opy ▁shows ▁that ▁its ▁stars ▁are ▁composed ▁almost ▁entirely ▁of ▁hydro gen ▁and ▁hel ium , ▁with ▁heav ier ▁elements ▁almost ▁completely ▁absent . ▁The ▁concentr ated ▁bl u ish - white ▁kn ots ▁embedded ▁in ▁the ▁heart ▁of ▁the ▁galax y ▁are ▁two ▁major ▁star bur st ▁regions ▁where ▁stars ▁are ▁forming ▁at ▁a ▁fur ious ▁rate . ▁The ▁wis py ▁blue ▁fil aments ▁surrounding ▁the ▁central ▁star bur st ▁regions ▁are ▁b ub bles ▁of ▁gas ▁that ▁have ▁been ▁blow n ▁away ▁by ▁stell ar ▁wind s ▁and ▁super nov ae ▁explos ions ▁from ▁a ▁previous ▁generation ▁of ▁hot , ▁young ▁stars . ▁This ▁gas ▁is ▁now ▁he ated ▁by ▁inten se ▁ult rav io let ▁radiation ▁un le ashed ▁by ▁a ▁new ▁generation ▁of ▁hot , ▁young ▁stars . ▁ ▁References ▁ ▁External ▁links ▁ ▁Astronom ers ▁claim ▁first ▁' dark ▁galax y ' ▁find ▁ ▁Zo om ▁in ▁I ▁Z wick y ▁ 1 8 . ▁ ▁Category : I r regular ▁galaxies ▁Category : D war f ▁irregular ▁galaxies ▁ 1 - 1 8 ▁ 2 7 1 8 2 ▁Category : UG CA ▁objects <0x0A> </s> ▁Se kol ah ▁Men eng