American Association of Variable Star Observers | 2019 Aug 14
An international team of astronomers succeeded in detecting signs of aging in the red supergiant star T UMi. The star in the Little Bear constellation is currently going through its last nuclear “hiccups,” and will soon end its 1.2 billion year-long life.
Imagine that you are a fly and you want to figure out how humans age. You don't have the time to just pick one specimen and wait it out: you need to work with what you see right now, and try to make sense of it somehow. This is the core problem of figuring out stellar evolution under human lifetimes.
The lives of stars progress very gradually, and most of the time we cannot detect the passage of time in these objects. A well-known exception to this rule is a supernova explosion, but the vast majority of stars do not experience this phase. Stars similar to the Sun end their lives much more quietly: they turn into red supergiants and then into planetary nebulae after a few billion years, and leave behind only a small white dwarf as a remnant.
Astronomers have pieced together evidence of this sequence by observing millions of stars, each with different age and mass, and by calculating "typical," or average, behavior using stellar models. However, it is difficult to find direct evidence that any particular star follows this path.
Researchers at the Konkoly Observatory of the Hungarian Academy of Sciences, Dr. László Molnár and Dr. László Kiss, and their international collaborator, Dr. Meridith Joyce, at the Australian National University, have now succeeded at uncovering direct evidence of this evolution thanks to a brief window of opportunity at the end of the lives of smaller stars. ...
Stellar Evolution in Real Time: Models Consistent with the Direct Observation
of a Thermal Pulse in T Ursae Minoris ~ László Molnár, Meridith Joyce, László Kiss
- Astrophysical Journal 879(1):62 (2019 Jul 01) 10.3847/1538-4357/ab22a5
- arXiv.org > astro-ph > arXiv:1905.00597 > 02 May 2019 (v1), 04 Jun 2019 (v2)