, ▁but ▁it ▁is ▁unclear ▁how ▁this ▁can ▁fit ▁with ▁the ▁prop ly d ▁scenario . ▁ ▁D ust ▁wave ▁ ▁In ▁inf ra red ▁images , ▁a ▁prominent ▁arc ▁is ▁visible ▁cent red ▁on ▁ σ ▁Ori ▁AB . ▁ ▁It ▁is ▁about ▁ 5 0 " ▁away ▁from ▁the ▁class ▁O ▁star , ▁around ▁ 0 . 1 ▁parse cs ▁at ▁its ▁distance . ▁ ▁It ▁is ▁directed ▁towards ▁IC 4 3 4 , ▁the ▁Hor ese head ▁Neb ula , ▁in ▁line ▁with ▁the ▁space ▁motion ▁of ▁the ▁star . ▁ ▁The ▁appearance ▁is ▁similar ▁to ▁a ▁bow sh ock , ▁but ▁the ▁type ▁of ▁radiation ▁shows ▁that ▁it ▁is ▁not ▁a ▁bow sh ock . ▁ ▁The ▁observed ▁inf ra red ▁emission , ▁pe aking ▁at ▁around ▁ 4 5 ▁mic rons , ▁can ▁be ▁model led ▁by ▁two ▁approximately ▁black - body ▁components , ▁one ▁at ▁ 6 8 K ▁and ▁one ▁at ▁ 1 9 7 ▁K . ▁ ▁These ▁are ▁thought ▁to ▁be ▁produced ▁by ▁two ▁different ▁sizes ▁of ▁dust ▁gra ins . ▁ ▁The ▁material ▁of ▁the ▁arc ▁is ▁the or ised ▁to ▁be ▁produced ▁by ▁photo ev ap oration ▁from ▁the ▁mole cular ▁cloud ▁around ▁the ▁Hor se head ▁Neb ula . ▁ ▁The ▁dust ▁becomes ▁dec ou ple d ▁from ▁the ▁gas ▁that ▁carried ▁it ▁away ▁from ▁the ▁mole cular ▁cloud ▁by ▁radiation ▁pressure ▁from ▁the ▁hot ▁stars ▁at ▁the ▁centre ▁of ▁the ▁ σ ▁Ori ▁cluster . ▁ ▁The ▁dust ▁accum ul