[13] The visual brightness is increasing by about 0.15 magnitude per century, attributed to a slow decrease in temperature at constant luminosity.

In more recent centuries, it has been very slowly increasing in visual magnitude and decreasing in temperature, which has been interpreted as the expected evolutionary trend of a massive star towards a red supergiant stage.

[18] Luminous blue variables like P Cygni are very rare and short lived, and only form in regions of galaxies where intense star formation is happening.

The recent supernova SN 2006gy was likely the end of an LBV star similar to P Cygni but located in a distant galaxy.

[18] It has been identified as a possible type IIb supernova candidate in modelling of the fate of stars 20 to 25 times the mass of the Sun (with LBV status as the predicted final stage beforehand).

The emission line arises from a dense stellar wind near to the star, while the blueshifted absorption lobe is created where the radiation passes through circumstellar material rapidly expanding in the direction of the observer.

Infall of matter into the secondary star would produce the release of gravitational energy, part of which would cause an increase of the luminosity of the system.