The yellow hypergiant - B[e] supergiant connection

TL;DR

This paper explores the connection between B[e] supergiants and yellow hypergiants by analyzing their circumstellar environments, revealing disk structures and mass-loss behavior changes during stellar evolution.

Contribution

It provides evidence of disk-like structures around yellow hypergiants and proposes their evolutionary link to B[e] supergiants based on circumstellar properties.

Findings

Presence of Keplerian disks around yellow hypergiants

Change from spherical to axisymmetric mass loss during evolution

Yellow hypergiants may evolve into B[e] supergiants

Abstract

B[e] supergiants and yellow hypergiants share a number of common properties regarding their circumstellar environments. Using the forbidden [O I] and [Ca II] lines as disk tracers, we suggest the presence of a Keplerian disk or ring around the yellow hypergiant V509 Cas and confirm the pole-on inner disk around V1302 Aql. These findings indicate a change in mass-loss behavior from spherical in cooler yellow hypergiants to axisymmetric in the hotter ones during the passage through the Yellow Void. The accumulation of material in the equatorial plane reminds of the disks of B[e] supergiants, supporting the suggestion that yellow hypergiants might appear as B[e] supergiants after they reach the blue edge of the yellow instability domain.