As someone who lacks luck and attracts clouds, lighting, and power outages, I am happy to say there are areas of astronomy that just require a lot of patience and detail-focused work. This style of research is showcased in a paper led by Patrick Gauime and appearing in Astronomy & Astrophysics. 

In this very different style of research, this team looked through data on the roughly 4500 red giant stars in the NASA Kepler data set and looked for stars that weren’t behaving in normal, boring, red giant kind of ways. In general, red giants are placid stars that slowly rotate and don’t have many or any starspots on their surface. These two factors are connected – a star’s magnetic field is driven in part by the stars rotation rate, and it is that magnetic field that generates spots. Smaller, younger stars like our Sun rotate quickly and have spots, but when they expand into red giants in later life, conservation of angular momentum will force them to rotate slower, like an ice skater extending their arms outward.

This is what usually happens at least.

But as I said, this team was looking for something unusual – they were looking for red giants that have starspots.

And they found them.

Roughly, 8% of the red giants in this survey showed the changes in the brightness characteristic of a spotty rotating star. These same stars also have short rotation periods, indicating that something spun up them and their magnetic field. It’s in trying to figure out how you spin up a giant star that things get interesting. They suggest reasons ranging from forced synchronization with another, closely neighboring star, to the swallowing of a star or planet, to a fast initial rotation speed in an early phase of development. The cool thing is, it doesn’t have to be just one reason accelerating the stars – different things could happen in different places. Now we get to see if observations can find evidence of any of these causes. If it’s found, we’ll bring it to you here on the Daily Space.

Finding weird things and then getting to explain them is why a lot of people like doing science. Large stars are one of those things that regularly demonstrate they can be more unexplainable than a giant ball of plasma seems like it should be.

More Information

Max Planck Institute for Solar System Research news release 

“Active Red Giants: Close Binaries Versus Single Rapid Rotators,” Patrick Gaulme, Jason Jackiewicz, Federico Spada et al., 2020 July, Astronomy & Astrophysics (Preprint on arxiv.org)