▁two ▁stars ▁with ▁late - O ▁or ▁early - B ▁spectral ▁types , ▁but ▁the ▁cluster ▁also ▁contains ▁hundreds ▁of ▁lower - mass ▁stars . ▁This ▁region ▁is ▁also ▁home ▁to ▁objects ▁with ▁Her big – H aro ▁j ets , ▁H H ▁ 1 0 4 2 ▁and ▁H H ▁ 1 0 4 3 . ▁ ▁Star ▁formation ▁in ▁RC W ▁ 3 6 ▁Like ▁most ▁star - form ing ▁regions , ▁the ▁inter stell ar ▁medium ▁around ▁RC W ▁ 3 6 ▁contains ▁both ▁the ▁gas ▁from ▁which ▁stars ▁form ▁and ▁some ▁newly ▁formed ▁young ▁stars . ▁Here , ▁young ▁stell ar ▁clusters ▁form ▁in ▁giant ▁mole cular ▁clouds . ▁M ole cular ▁clouds ▁are ▁the ▁col dest , ▁dens est ▁form ▁of ▁inter stell ar ▁gas ▁and ▁are ▁composed ▁mostly ▁of ▁mole cular ▁hydro gen ▁( H 2 ), ▁but ▁also ▁include ▁more ▁complex ▁mole cules , ▁cos mic ▁dust , ▁and ▁atomic ▁hel ium . ▁Stars ▁form ▁when ▁the ▁mass ▁gas ▁in ▁part ▁of ▁a ▁cloud ▁becomes ▁too ▁great , ▁causing ▁it ▁to ▁collapse ▁due ▁to ▁the ▁Je ans ▁inst ability . ▁Most ▁stars ▁do ▁not ▁form ▁alone , ▁but ▁in ▁groups ▁containing ▁hundreds ▁or ▁thousands ▁of ▁other ▁stars . ▁RC W ▁ 3 6 ▁is ▁an ▁example ▁of ▁this ▁type ▁of ▁" cluster ed " ▁star ▁formation . ▁ ▁M ole cular ▁cloud ▁and ▁H ▁II ▁region ▁▁ ▁The ▁V ela ▁M ole cular ▁R idge ▁can ▁be ▁sub div ided ▁into ▁several ▁smaller ▁clouds , ▁each