An artist’s impression of the accretion disk, envelopen, and streamers surrounding the massive protostar G359.44-0.102 (generated using AI based on the scientific paper).

Recently, researchers from Shanghai Astronomical Observatory have conducted high-resolution observations of the Galactic Center region using the Atacama Large Millimeter/submillimeter Array (ALMA), focusing on an early O-type massive protostar and its surrounding Keplerian accretion disk in the Sagittarius C molecular cloud within the Central Molecular Zone (CMZ). The research team carried out a detailed analysis of the emission features and spatial distribution of complex organic molecules in this system, uncovering the intricate dynamical structure among the inner accretion disk, outer envelope, and gravitationally collapsing accretion flows. This achievement provides crucial observational evidence for understanding the mass accumulation process of early O-type stars in extreme environments and has been published in The Astrophysical Journal.

The CMZ, located approximately 8.3 kiloparsecs from Earth, represents the most extreme environment in the Milky Way. The research team observed the massive protostar G359.44-0.102 located in this region. The results reveal a clear chemical differentiation in the molecular emission surrounding this star: nitrogen-bearing molecules are predominantly concentrated in a compact inner region, while oxygen-bearing molecules exhibit a more extended and diffuse distribution. Meanwhile, by constructing a three-dimensional dynamical model incorporating an inner Keplerian disk and an outer free-fall envelope, the researchers have precisely constrained the mass of the central protostar and the structure of the accretion disk. The study further analyzes the efficiency of material transport toward the central star.

In addition, the team identified spiral structures and velocity gradients in both the dust continuum and molecular line-of-sight velocity field of the disk. Particle trajectory modeling confirms that these spiral structures are, in fact, accretion streams undergoing gravitational collapse and spiraling inward toward the central protostar.

This study enriches our understanding of the accretion mechanisms of massive protostars in extreme environments. In the CMZ, a region where the overall star formation efficiency is significantly suppressed due to factors such as extremely high turbulence, massive protostars can still rapidly accumulate mass through the combined action of the accretion disk, envelope, and accretion flows. This indicates that at the gravity-dominated accretion disk scale, star formation activity is insensitive to macroscopic large-scale environmental conditions, revealing the universality of disk-mediated accretion across different environments in the Milky Way.

DOI: https://doi.org/10.3847/1538-4357/ae6813

Science Contacts: Jixiang WENG, wengjixiang@shao.ac.cn; Xing LV, xinglu@shao.ac.cn