Eta Carinae and Nebulae Around Massive Stars: Similarities to Planetary Nebulae?

TL;DR

This paper compares the shapes of nebulae around massive stars and planetary nebulae, suggesting similar formation mechanisms like bipolar ejections, with Eta Carinae as a key example, highlighting observational evidence for intrinsic bipolar explosions.

Contribution

It presents observational evidence supporting the idea that bipolar nebulae around massive stars and planetary nebulae may share similar intrinsic formation processes.

Findings

Eta Carinae's bipolar nebula likely formed from an intrinsic bipolar explosion.

Similar bipolar ejection processes are inferred for some planetary nebulae.

Observational similarities suggest common shaping mechanisms across different stellar environments.

Abstract

I discuss some observational properties of aspherical nebulae around massive stars, and conclusions inferred for how they may have formed. Whether or not these ideas are applicable to the shaping of planetary nebulae is uncertain, but the observed similarities between some PNe and bipolar nebulae around massive stars is compelling. In the well-observed case of Eta Carinae, several lines of observational evidence point to a scenario where the shape of its bipolar nebula resulted from an intrinsically bipolar explosive ejection event rather than an interacting winds scenario occurring after ejection from teh star. A similar conclusion has been inferred for some planetary nebulae. I also briefly mention bipolar nebulae around some other massive stars, such as the progenitor of SN 1987A and related blue supergiants.