Global and Local Infall in the ASHES Sample (GLASHES). I. Pilot Study in G337.541

Summary

The study observes a 70µm dark massive clump, G337.541-00.082, using ALMA, revealing infall motions around cores, which is crucial for high-mass star formation.

Highlights

• N H+ (J =1−0) line detects a clump-scale velocity gradient and high-speed tail components tracing outflow lobes.
• HNC (J = 3−2) and HCO+ (J = 3−2) lines exhibit similar spatial distributions, but HCO+ is more affected by outflows.
• Position-velocity diagram of N 2H+ shows a curvy structure, implying gas acceleration toward the central sub-clump.
• Nine cores show blue-asymmetry profiles, indicating infall motions.
• Infall velocity is estimated to be between 0.28 and 1.45 kms−1.
• Mass infall rate of the most massive core is estimated as 2.9×10−3M yr−1.
• Infall velocity correlates with nonthermal velocity dispersion and Mach number.

Key Insights

• The detection of infall motions around cores in G337 supports the core growth scenario, where cores grow through gas feeding from the surrounding environment, enabling the formation of high-mass stars.
• The high infall velocity and mass infall rate in G337 compared to low-mass star-forming regions suggest a more dynamic environment that can affect star formation.
• The correlation between infall velocity and nonthermal velocity dispersion implies that the latter is contaminated with infall motions, not purely tracing internal turbulence.
• The study's findings propose that infall motions play a crucial role in the formation of high-mass stars, supporting the core growth scenario.
• The observed infall velocity and mass infall rate in G337 are significantly larger than those in low-mass star-forming regions, despite having similar core masses.
• The timescale derived from the velocity gradient is comparable to the free-fall time, indicating that the cores are under gravitational collapse rather than supported by magnetic fields.
• The study highlights the importance of considering the environment in the star formation process, as it can impact the formation of high-mass stars.

Mindmap

Citation

Morii, K., Sanhueza, P., Csengeri, T., Nakamura, F., Bontemps, S., Garay, G., & Zhang, Q. (2024). Global and Local Infall in the ASHES Sample (GLASHES). I. Pilot Study in G337.541 (Version 1). arXiv. https://doi.org/10.48550/ARXIV.2412.17901