Blue Straggler Star

Blue Straggler Star Latest News

Recently, Indian astronomers, along with their international collaborators, have reported the rare discovery of a Blue Straggler Star (BSS). 

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

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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.

Source: PIB