Some good news.
The star is very similar in type to the star Eta Carinae which would have looked very similar during its gamma cassiopeiae outburs in the mid 1850s.
As with Eta carinae the star likely has a closed captured cell in the core with equatorial disc inflow and polar outflow, with evolution with time to a white supergiant as the core cell becomes contaminated with fusion products. For a 3D idea of the mechanism a peek @ the avatar pic (actually the galaxy M104) would give a clue to the goings on.
The outburst is likely a result of the formation of a droplet of fusion product in the core which inflated the star into a red supergiant followed in the space of a few months with the star still expanding its outer layers by...
The ignition of the interior droplet of fusion product and the formation of a new core cell leaving the outer layers hanging and eventually to form an hourglass nebula with about half of the equatoria region falling back onto the star.
The nuclear fusion stage is completely unknown (Eta Carinae appears to currently be an O burner). Keep watching that space, if it was an Si burning gamma cassiopeiae event the next droplet of fusion product to form in the core is likely to be Fe with the result being a rather spectacular supernova and the formation of a stellar mass black hole.
One previous stellar outburst event (initially classed as a supernova) turned out to be a gamma cassiopeiae core ignition event with the star becoming a genuine supernova about 2 years later from within its hourglass bubble nebula accompanied by a reflection gamma ray burst from the black hole outflow jets.
The onion shell model for type 2 supernovae appears to the bunkum for the massive stars in particular and only appears to apply to stars of 3 to 5 solar masses (probably an overestimate) at the Fe core stage. There are rather a lot of low mass type 2 supernovae because low mass stars are more common than the spectacularly luminous high mass examples.
For comparison, most likely type 2 supernova candidates of low mass are likely to be Epsilon Aurigae, Canopus, and Betelgeuse. A core ignition event would however turn Belelgeuse into a Rigel type blue supergiant which will then slowly return to red vai a yellow supergiant stage. The collapse of a red supergiant to a blue supergiant during core ignition would likely ALSO be a gamma cassiopeiae event similar to the outburst of P cygni in 1600AD.
Awaiting results with interest.
Have a nice day: Ag