Stingray Nebula and SAO 244567

This image of the Stingray nebula, a planetary nebula 2700 light-years from Earth, was taken with the Wide Field and Planetary Camera 2 (WFPC2) in 1998. In the centre of the nebula the fast evolving star SAO 244567 is located. Observations made within the last 45 years showed that the surface temperature of the star increased by almost 40 000 degree Celsius. Now new observations of the spectra of the star have revealed that SAO 244567 has started to cool again.