A dead star switched back on in 1996, and it's still changing fast enough to watch
Watching a star change is normally hopeless. You get one frame out of a movie that runs for millions of years. That's why I like this story so much.
Astronomers from the University of Manchester and the Valongo Observatory have been following something called Sakurai's Object. It's a star that had already finished its life, and then in 1996 it flared back up. People call these born-again stars. Some leftover fuel near the surface catches, and the dead thing runs again for a while.
The team used the Very Large Telescope in Chile, and they found it has moved into a new phase. It now has the kind of strong stellar wind you see in Wolf-Rayet stars, and its surface temperature is somewhere around 27,000 to 36,000 Kelvin. That makes it about six times hotter than it was thirty years ago. They say it's one of the fastest temperature climbs ever recorded for a star. The work is published in Monthly Notices of the Royal Astronomical Society.
The part that gets me is the timescale. Most theories about how stars die can't be checked directly, because the whole process takes longer than our species has been around. This one is running at a speed one person can follow. Somebody who started watching this star as a student could still be watching it now and be looking at a genuinely different object.
I'll keep an eye on where it goes next.