The BM Ori System. II. Abundances of Helium and Iron in the Atmosphere of the Primary Star

The abundances of helium and iron in the atmosphere of the principal star of the BM Ori system are estimated. Spectra obtained with the BTA telescope and from the archives of the IUE and HST satellites are used. It turns out that the helium abundance is close to that in the sun, while that of iron is lower. The helium and iron abundances in other stars of the Trapezium of Orion are generally similar to those in BM Ori, but there are some differences. For example, of the two stars θ¹ Ori C and θ¹Ori D, one has a higher and the other a lower abundance of helium than does the sun. At the same time, the secondary of BM Ori has a normal abundance of iron.