Disk formation in oblate B[e] stars

TL;DR

This study explores how line-driven winds, especially the $oldsymbol{ ext{Ω}}$-slow solution, influence disk formation in oblate B[e] stars, revealing significant equatorial density enhancements compared to polar regions.

Contribution

It demonstrates the impact of the $oldsymbol{ ext{Ω}}$-slow wind solution and oblate correction factors on circumstellar density contrasts in B[e] stars.

Findings

Density contrast between equator and pole exceeds 100.

Oblate correction factors amplify density contrasts.

Fast polar winds coexist with slow, dense equatorial winds.

Abstract

We investigate the possible role of line-driven winds in the circumstellar envelope in B[e] stars, mainly the role of the $\Omega$-slow wind solution, which is characterized by a slower terminal velocity and higher mass-loss rate, in comparison with the standard (m-CAK) wind solution. In this work, we assume two scenarios: 1) a spherically symmetric star and 2) a scenario that considers the oblate shape, considering only the oblate correction factor. For certain values of the line force parameters (according to previous works), we obtain in both scenarios a density contrast $\gtrsim10^{2}$ between equatorial and polar densities, characterized for a fast polar wind and a slow and denser wind when the $\Omega$-slow wind solution is obtained. All this properties are enhanced when the oblate correction factor is included in our calculations.