Forty years ago a star appeared as a "nova" - and we are still learning more about it.

This nova occurred when a burnt-out star sucked gas from a bloated red giant companion orbiting it. The star system, called HM Sagittae, became 250 times brighter and remained so for decades. However, recent observations by Hubble show that the star system is getting hotter but paradoxically fading a little.

Image description:

An artist's concept of the binary star system HM Sge, in which red and white points of light of various sizes are interspersed against the black background of space. A bright white disc in the upper part of the image surrounds a white dwarf star that is drawing material from its red giant companion, the glowing speckled ball in the lower right.

Doesn't it look like a spinning top?