The B[e] Phenomenon in Supergiants. A Result of Mass Transfer in Binaries, Mergers, or What?

TL;DR

The paper surveys the B[e] phenomenon in supergiants (sgB[e]) as a clue to circumstellar matter shaped by binary interaction, mass transfer, mergers, or multiple-system dynamics. It compiles and extends the sgB[e] roster, leveraging IR dust signatures and Gaia DR3 distances to refine luminosities and reassess classifications. The authors argue that binarity is common among sgB[e]s, but some objects may be merger remnants or require triple-system scenarios, drawing on cases like η Car and FS CMa-like objects. The study highlights the need for multi-technique observations to disentangle the origins of the B[e] phenomenon and the role of stellar evolution in binary contexts.

Abstract

The B[e] phenomenon discovered nearly 50 years ago features the presence of forbidden emission lines due to extended and dense circumstellar gas and large IR excesses due to the radiation from circumstellar dust in a wide variety of objects from pre-main-sequence stars to Planetary Nebulae. It also shows up in a small group of supergiants that includes Luminous Blue Variables, such as η Carinae. Over the years, some of them were proven to be binary systems, but the presence of a secondary component in other is still elusive. At the same time, there is growing evidence that the B[e] phenomenon can be due to binary mergers or interactions in triple systems.