  On the basis of far-infrared images obtained by the Herschel Space
Observatory, we report the discovery of a large and massive dust shell around
the yellow hypergiant Hen3-1379 . The nebula appears as a detached ring of 1 pc
diameter which contains 0.17 Msun of dust. We estimate the total gas mass to be
7 Msun, ejected some 16000 years ago. The ring nebula is very similar to
nebulae found around luminous blue variables (LBVs) except it is not
photoionized. We argued that Hen3-1379 is in a pre-LBV stage, providing direct
evidence that massive LBV ring nebulae can be ejected during the red supergiant
phase.
