NGC 300 OT2008-1 As a Scaled-Down Version of the Eta Carinae Great Eruption

TL;DR

This paper suggests that the NGC 300 OT2008-1 transient was caused by mass transfer in a binary system, sharing characteristics with other major stellar eruptions, and proposes a common energy mechanism involving accretion.

Contribution

It introduces the idea that intermediate luminosity optical transients are powered by accretion, linking various events through a shared energy source and ejecta geometry.

Findings

NGC 300 OT2008-1's light curve resembles other stellar eruptions.

These transients occupy a specific energy-duration diagram strip.

Accretion onto a star likely powers these events.

Abstract

We propose that the intermediate luminosity optical transient NGC 300 OT2008-1 was powered by a mass transfer episode from an extreme Asymptotic Giant Branch star to a Main Sequence companion. We find a remarkable similarity of the shapes of the light curves of the several months long NGC 300 OT2008-1 outburst, of the three months long 2002 enigmatic outburst of the B star V838 Mon, and the twenty-years long Great Eruption of the massive binary system Eta Carinae that occurred in the 19th century. Their similar decline properties hint to a common energy source: a gravitational energy that is released by accretion onto a main sequence star. These events populate a specific strip in the total energy vs. outburst duration diagram. The strip is located between novae and supernovae. We add recent transient events to that diagram and find them to occupy the same strip. This suggests that some intermediate luminosity optical transients are powered by accretion onto a compact object (not necessarily a main sequence star). These transients are expected to produce bipolar ejecta as a result of the geometry of the accretion process.