Hα19 in the galaxy M33, a high-luminosity massive merging eclipsing binary

CCD photometry reveals a hot spot on the surface of the hot accretion gainer in this supergiant O type binary with a big accretion rate. This spot is as bright as 25000 Suns. The orbital period of this system is 33.108 days. The absorption-line spectrum contains multiple lines of He I, Si III and N II. The star is associated with H II region formed by bipolar gas outflow from the system.