Object name: NGC0188
NGC 188 is the northernmost and one of the oldest known open star clusters. It is less than 5 degrees from the pole and over 5 billion years old. What surprised me was that at such an old age it has a rather large population of blue stars. I found surprisingly few color images of this cluster but what few I found also saw the large population of bright blue stars. I was then surprised to learn there are 21 known blue stragglers in this cluster. They are common in globular clusters where the idea is that stars are so compact collisions near the core can occur creating a massive blue star in place of two old yellow or red stars. That doesn't seem reasonable for an open star cluster, however. It's thought these are close binary stars with one member now an unseen white dwarf. During its giant phase, the companion acquired most of the outer halo of the more evolved companion increasing its mass turning the star into a rather massive blue star while the evolved companion was quickly reduced to white dwarf status. But there are far more than 21 blue stars in my image. So which are the blue stragglers? I have no idea.