A large shell around the hypergiant VY Canis Majoris

Abstract: We report the detection of a remarkable shell around the red hypergiant VY CMa using data from the Spectro-Photometer for the History of the Universe, Epoch of Reionization, and Ices Explorer (SPHEREx). The shell, which in projection on the plane of the sky appears as a ring, is almost circular in appearance. It has an external diameter of $\sim14'$ to $15'$, and is seen most clearly in the SPHEREx 7827A spectro-photometric image. Filaments, radially aligned with VY CMa, are seen to cut across the shell in several places. We discuss the possibility that the shell is matter swept out from the neighboring star forming region Sh 2-310, by the wind from VY CMa. Resonant atomic scattering, a light echo, or Extended Red Emission are explored as the source of the observed SPHEREx emission. However, no interpretation is without difficulty and further observations are most desirable.