Star clusters, groups of stars formed together, are essential to understanding how stars evolve and impact the galaxy. Young clusters, less than 30 million years old, release energy through stellar winds and could potentially accelerate particles to produce cosmic rays. The paper investigates the energy from these stellar winds in 387 Galactic clusters identified in the Gaia DR2 catalog, aiming to understand their role in high-energy astrophysical processes.

Methods

The team calculated the mass and wind power of these clusters by analyzing the stars in each group. They assumed stars follow a mass distribution pattern and used Gaia's detailed data on star magnitudes, distances, and extinction (how much light is blocked by dust). By correlating these properties, they estimated the cluster's total mass and the power of its stellar winds.

Results

The researchers found that their method produced a larger sample of massive clusters than previous studies. Their analysis revealed that some clusters have wind luminosities reaching up to a significant value for particle acceleration and gamma-ray production. However, their estimates are likely lower limits due to missing data and assumptions.

Comparison with Other Studies

The authors compared their results with other methods that calculate cluster masses, such as tidal radius measurements and Monte Carlo simulations. Their approach captured more massive clusters, though it might underestimate the actual masses. Incorporating additional factors, like binary stars, could improve accuracy.

Wind Luminosities

Stellar winds, driven by the energy from massive stars, contribute to a cluster's wind luminosity. By combining Gaia data and models of star evolution, the researchers calculated how much energy these winds generate. Including data on Wolf-Rayet stars—high-energy stars in their final stages—helped refine these estimates.

Implications for Cosmic Ray Physics

The study supports the idea that young clusters can act as "particle accelerators," producing cosmic rays observed in the galaxy. This has implications for understanding high-energy phenomena like gamma rays detected near massive star clusters.

Conclusion

Gaia's data provides a powerful tool for studying young star clusters and their energetic output. This work highlights the potential of stellar winds in powering cosmic phenomena and sets the stage for further research into their high-energy impacts.

Source: Celli