Spectroscopic study of Of^+^ supergiants

The transition from early Of stars to WN-type objects is poorly understood. O-type supergiants with emission lines (OIf^+^) are considered to be intermediate between these two...早型Of星（early Of stars）向WN型天体（WN-type objects）的演化过渡机制目前仍未得到充分阐释。带有发射线的O型超巨星（OIf⁺）被认为是这两类天体之间的中间过渡天体。