Follow-Up of Extended Shells around B[e] Stars

Abstract

B[e] stars are massive B type emission line stars in different evolutionary stages ranging from pre-main sequence to post-main sequence. Due to their mass loss and ejection events these objects deposit huge amounts of mass and energy into their environment and enrich it with chemically processed material, contributing significantly to the chemical and dynamical evolution of their host galaxies. However, the large-scale environments of these enigmatic objects have not attracted much attention. The first and so far only catalog reporting the detection of extended shells around a sample of B[e] stars was an Hα imaging survey carried out in the year 2001, and was limited to bright targets in the northern hemisphere. We have recently started a follow-up of those targets to detect possible evolution of their nebulae in the plane of the sky over a baseline of two decades. Furthermore, we extend our survey to southern targets and fainter northern ones to complement and complete our knowledge on large-scale ejecta surrounding B[e] stars. Besides imaging in Hα and selected nebular lines, we utilize long-slit and 3D spectral observations across the nebulae to derive their physical properties. We discovered pronounced nebula structures around 15 more objects, resulting in a total of 27 B[e] stars with a large-scale nebula. Here we present our (preliminary) results for three selected objects: the two massive supergiants MWC137 and MWC 314, and the unclassified B[e] star MWC 819.

Discovering New B[e] Supergiants and Candidate Luminous Blue Variables in Nearby Galaxies

“…B[e]SGs tend to have initial masses with a wide range below the most luminous LBVs, and in accordance with the less luminous ones. The presence of similar lines in their spectra points to similarities in their CSEs, with shells and bipolar nebulae observed in both cases [22,25,26].…”

Gemini-LIGHTS: Herbig Ae/Be and Massive T Tauri Protoplanetary Disks Imaged with Gemini Planet Imager

“…However, previous studies were at a larger spatial scale (>1′) and emission, while our observations are at smaller spatial scales and from a polarized source. Finally, our targets have a lower mass than those studied by Marston & McCollum (2008) and Liimets et al (2022).…”

“…Previous studies have detected extended structures around B [e] stars via H-alpha (Marston & McCollum 2008;Liimets et al 2022). These structures are typically shell-like or indicative of bipolar outflows.…”

Dense Molecular Environments of B[e] Supergiants and Yellow Hypergiants

“…The group of B[e]SGs consists of luminous (log(L * /L ⊙ ) ≥ 4.0) post-main sequence B-type emission line stars. Besides large-scale ejecta (with sizes of several pc) detected in some B[e]SGs [3,9], all objects have intense winds and are surrounded by massive disks on small scales (up to ∼100 AU) [15][16][17], giving rise to the specific emission features characterizing stars with the B[e] phenomenon [18]. These disks give shelter to a diversity of molecular and dust species, and the near-infrared (NIR) is an ideal wavelength regime to detect molecular emission features that, when resolved with high spectral resolution, provide insight into the physical properties of the disks and reveal the disk dynamics.…”