Nov 1, 2019
It shouldn't exist, but it does.
As our Sun grows older and the hydrogen begins to deplete and Helium increase, it will eventually turn into a red giant. The current theory is that the inner planets will be engulfed by the expanding sun as it does.
So stars that have already entered the red giant phase are important for study, particularly if they appear to have planets still, and even more so if close in planets appear to have somehow survived the transition to red giant.
Our knowledge of the evolution of star systems is very much in its infancy, as we have only just started in the last 2 decades to actually see exoplanets and catalogue them.