On the Evolution of BM Orionis

Abstract

BM Orionis, eclipsing binary system that located in the center of Orion Nebula Cluster posses several enigmatic problems. Its intrinsic nature and nebular environment make it harder to measure the physical parameters of the system, but it is believed as Algol type binary where secondary component is pre-main sequence star with larger radius. To assure this, several stellar models ($M_1=5.9$ {M_{\odot}} and $M_2=2.0$ {M_{\odot}}) are created and simulated using MESA. Models with rigid rotation of $\omega=10^{-5}$ rad/s exhibit considerable similar properties during pre-main sequence stage, but 2.0 {\msun} at assumed age of $\sim10^6$ is $6.46$ times dimmer than observed secondary star. There must be an external mechanism to fill this luminosity gap. Then, simulated post-main sequence binary evolution of BM Ori that involves mass transfer shows that primary star will reach helium sequence with the mass of $\sim0.8$ {\msun} before second stage mass transfer.