About Blue Straggler Star:
- These are a peculiar class of stars found in star clusters that appear hotter, brighter, and more massive than their peers.
- They have a different trajectory of evolution from the norm.
- These are observed in old, dense stellar systems such as globular clusters.
- They lie on an extension of the main sequence star and are bluer and brighter than the main-sequence turn-off stars.
- These objects are found in star clusters, dwarf galaxies, and in the field.
How are Blue Straggler Stars Different?
- There are a few stars, when they are expected to start expanding in size and cooling down, do just the opposite.
- They grow brighter and hotter as indicated by their blue colour, thus standing out from the cooler red stars in their vicinity in the colour-magnitude diagram.
- Since they lag behind their peers in evolution, they are called stragglers, more specifically, blue stragglers, because of their hot, blue colour.
Why do they Behave Differently?
- Possibility 1: They do not belong to the family of stars in the cluster, and hence not expected to have the group properties.
- Possibility 2: The straggler draws matter from the giant companion star and grows more massive, hot and blue, and the red giant to end up as a normal or smaller white dwarf.
- Possibility 3: The straggler draws matter from a companion star, but that there is a third star that facilitates this process.
