Stars become overweight due to stellar cannibalism

January 15th, 2009 - 12:38 pm ICT by ANI  

London, Jan 15 (ANI): In a new research, scientists have discovered that the mysterious overweight stars known as blue stragglers are the result of stellar cannibalism where plasma is gradually pulled from one star to another to form a massive, unusually hot star that appears younger than it is.

The research was part funded by the UKs Science and Technology Facilities Council (STFC) and carried out by scientists at Southampton University and the McMaster University in Canada.

Blue stragglers are found throughout the Universe in globular clusters - collections of about 100, 000 stars, tightly bound by gravity.

According to conventional theories, the massive blue stragglers found in these clusters should have died long ago because all stars in a cluster are born at the same time and should therefore be at a similar phase.

These massive rogue stars, however, appear to be much younger than the other stars and are found in virtually every observed cluster.

The origin of blue stragglers has been a long-standing mystery. The only thing that was clear is that at least two stars must be involved in the creation of every single blue straggler, because isolated stars this massive simply should not exist in these clusters, said Dr Christian Knigge from Southampton University, who led the study.

Weve known of these stellar anomalies for 55 years now. Over time, two main theories have emerged: that blue stragglers were created through collisions with other stars; or that one star in a binary system was reborn by pulling matter off its companion, said Professor Alison Sills from the McMaster University.

The researchers looked at blue stragglers in 56 globular clusters.

They found that the total number of blue stragglers in a given cluster did not correlate with predicted collision rate dispelling the theory that blue stragglers are created through collisions with other stars.

They did, however, discover a connection between the total mass contained in the core of the globular cluster and the number of blue stragglers observed within in.

Since more massive cores also contain more binary stars, they were able to infer a relationship between blue stragglers and binaries in globular clusters.

They also showed that this conclusion is supported by preliminary observations that directly measured the abundance of binary stars in cluster cores.

All of this points to stellar cannibalism as the primary mechanism for blue straggler formation.

According to Dr Knigge, This is the strongest and most direct evidence to date that most blue stragglers, even those found in the cluster cores, are the offspring of two binary stars. (ANI)

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