All stars follow a specific path in the lives of theirs once they begin fusing hydrogen. As they live they continuously get hotter and brighter until they use fusing different elements. Every star follows this very same path…except the azure straggler stars.
As the names of theirs suggests, blue straggler stars are stars which show up in a bunch which are bluer and brighter than they ought to be. Specifically, they continue to lie along the key sequence, that is a certain relationship between temperature and brightness that all hydrogen fusing stars obey. But the trouble with blue stragglers is the fact that they should certainly not be sitting on the key sequence. They need to have died far back. Actually, in the exact same group astronomers will discover a number of other stars of equivalent mass with left the primary sequence and are fusing heavier elements.
Astronomers don’t completely understand just how azure straggler stars form. One particular theory is they’re the leftovers of a merger of 2 scaled-down mass stars. In this particular situation, the stars coalesce and merge together. At first that merged star is red and huge, since the serious rotation bloats it of proportion. But after sufficient time that overextended star settles down, developing a massive, bright, blue star.
In other scenario, blue stragglers form when one star cannibalizes a neighbor, sucking down its mass onto its own.
Clusters provide the ideal environment in which these mergers can take place. Clusters might be as dense as our local solar neighbourhood, a thousand times greater.
Essentially, blue straggler stars obtain a second chance at living in either model. They didn’t form at the same time as all of the other stars within exactly the same cluster in their present state. And so, according to our observations of their mass, they should have died long ago, we are currently seeing them start a whole new life post merger.
Understanding the origins of blue straggler stars helps astronomers piece together the complicated life stories of stars themselves, and especially what can happen to them after they merge.