Superluminous supernovae: No threat from Eta Carinae

TL;DR

This paper assesses the potential threat of Eta Carinae as a superluminous supernova progenitor, concluding it poses negligible risk to Earth due to its distance, atmospheric effects, and interstellar extinction.

Contribution

It reevaluates Eta Carinae's potential as a superluminous supernova progenitor and analyzes its atmospheric and biospheric impact risks.

Findings

Eta Carinae is unlikely to cause atmospheric ozone depletion.

Cosmic ray effects from Eta Carinae are spread over ~10^4 years, reducing threat.

Reddening and extinction diminish potential endocrine disruption effects.

Abstract

Recently Supernova 2006gy was noted as the most luminous ever recorded, with a total radiated energy of ~10^44 Joules. It was proposed that the progenitor may have been a massive evolved star similar to eta Carinae, which resides in our own galaxy at a distance of about 2.3 kpc. eta Carinae appears ready to detonate. Although it is too distant to pose a serious threat as a normal supernova, and given its rotation axis is unlikely to produce a Gamma-Ray Burst oriented toward the Earth, eta Carinae is about 30,000 times nearer than 2006gy, and we re-evaluate it as a potential superluminous supernova. We find that given the large ratio of emission in the optical to the X-ray, atmospheric effects are negligible. Ionization of the atmosphere and concomitant ozone depletion are unlikely to be important. Any cosmic ray effects should be spread out over ~10^4 y, and similarly unlikely to produce any serious perturbation to the biosphere. We also discuss a new possible effect of supernovae, endocrine disruption induced by blue light near the peak of the optical spectrum. This is a possibility for nearby supernovae at distances too large to be considered "dangerous" for other reasons. However, due to reddening and extinction by the interstellar medium, eta Carinae is unlikely to trigger such effects to any significant degree.