Shock fronts in the symbiotic system BI Crucis

TL;DR

This paper analyzes the spectral evolution of the symbiotic star BI Crucis over three decades, modeling shock interactions, wind collisions, and nebular structures to understand its physical conditions and history.

Contribution

It presents a comprehensive, self-consistent model explaining the nebular and dust features of BI Crucis, incorporating wind collision, jet formation, and past outburst effects.

Findings

Spectral data reveal signatures of shock interactions and post-outburst evolution.

Model accounts for wind collision, jet formation, and blast wave effects.

Spectra vary across epochs, indicating dynamic physical processes.

Abstract

We investigate the symbiotic star BI Crucis through a comprehensive and self-consistent analysis of the spectra emitted in three different epochs: 60's, 70's, and late 80's. In particular, we would like to find out the physical conditions in the shocked nebula and in the dust shells, as well as their location within the symbiotic system, by exploiting both photometric and spectroscopic data from radio to UV. We suggest a model which, on the basis of optical imaging, emission line ratios and spectral energy distribution profile, is able to account for collision of the winds, formation of lobes and jets by accretion onto the WD, as well as for the interaction of the blast wave from a past, unrecorded outburst with the ISM. We have found that the spectra observed throughout the years show the marks of the different processes at work within BI Cru, perhaps signatures of a post-outburst evolution. We then call for new infrared and millimeter observations, potentially able to resolve the inner structure of the symbiotic nebula.