Fast rotating blue stragglers prefer loose clusters

Area of Science:

• Astronomy and Astrophysics
• Stellar Evolution
• Stellar Dynamics

Background:

• Blue stragglers are luminous stars with unknown formation and evolutionary paths.
• They form through mass transfer or stellar collisions in binary/triple systems.

Purpose of the Study:

• To investigate the relationship between blue straggler rotation rates and their host globular cluster environments.
• To constrain the formation and evolutionary processes of blue stragglers.

Main Methods:

• Analysis of 320 high-resolution spectra of blue stragglers.
• Observation of stars in eight galactic globular clusters with varying densities.
• Measurement of blue straggler rotational velocities.

Main Results:

• The fraction of fast-rotating blue stragglers (v > 40 km/s) increases as the host cluster's central density decreases.
• Fast-spinning blue stragglers are preferentially found in lower-density environments.

Conclusions:

• Results indicate a preference for fast-spinning blue stragglers in low-density environments.
• This suggests recent blue straggler formation activity in such regions.
• Provides constraints on the timescale of slow-down processes in collisional blue stragglers.