A WN4 companion to BD +62 2296 in Cas OB5

Abstract

I report observations of the triple system BD +62 2296 showing that all its components are early-type stars, most likely physically related. The faintest component BD +62 2296B is a hitherto uncatalogued Wolf-Rayet star. The brightest component, star A, is shown to be a seemingly normal B2.5Ia supergiant. Long-slit spectroscopy of BD +62 2296B shows it to be a narrow-lined WN4 star. Given the spatial separation, the two objects are unlikely to form a physical binary. Spectra of the third visual component, BD +62 2296C, allow its classification as a B0III star. Such concentration of massive stars strongly suggests that BD +62 2296 is in reality a very compact young open cluster in the area of the OB association Cas OB5.