This finding provides proof that blue stragglers are created by collisions or other close encounters in an overcrowded cluster core. Their analysis will appear in the Nov. 1 issue of the Astrophysical Journal Letters. The team then combined these measurements with the blue straggler's apparent brightness, taken from a Hubble Telescope Wide Field and Planetary Camera archival image, to obtain the star's mass. The astronomers report the derived temperature and mass are consistent with the characteristics of a normal star with a mass about 1.7 times that of the Sun. However, the star is spinning at least two to three times faster than stars of its kind.
Astronomers now believe that blue stragglers are created by the merger of two low-mass stars.
But they have two different views of how these stars interact to create blue stragglers. One merger theory proposes that a violent collision of two unrelated stars creates a blue straggler. Another hypothesizes that a slow coalescence of a gravitationally bound pair creates the straggler star. Based on their analysis of the blue straggler in 47 Tuc, the team favors the slower, gentler merger scenario between binary stars. In double-star systems where the stars are close enough to touch each other, the more massive star can cannibalize its partner, producing a single, even more massive star.