J. Hwang, D. Arzoumanian, Y. Shimajiri, M Machida, S.-I. Inutsuka, M. S. N. Kumar, S Nozaki, K. Tokuda
Abstract
Hub─filament systems (HFSs) play an important role in the formation of massive stars and star clusters. Although the velocity structures along dense filaments have been studied, the gas kinematics in the low-density interfilament regions has not been investigated. We use 13CO (J = 1─0) and C18O (J = 1─0) observations obtained with the Nobeyama 45 m telescope to study the gas dynamics toward the Monoceros R2 (Mon R2) HFS. From the 13CO and C18O data, tracing low- and high-density gas, respectively, we identify velocity-coherent structures and divide them into Fs and IFs. We estimate the velocity gradients (∆v) and mass accretion rates ( Ṁ ) along (∥) and across (⊥) the filaments (F) and interfilaments (IFs). The mean ratio of Ṁ∥ to Ṁ⊥ in Fs is 6.8, while that in IFs is 1.5. These results show that the overall gas within both Fs and IFs flows directly into the hub and the gas flows faster along the Fs than the IFs. In addition, we find that at least 30% of the gas mass in the IFs may flow toward the Fs, replenishing the latter with new matter. Our study reveals the importance of considering the total gas-mass reservoir, both low- and high-density, infalling into the hub and promoting the formation of massive stars, which are preferentially located in the hub of Mon R2.
Keywords
Star formation / Molecular clouds / Interstellar medium / Massive stars / 1569 / 1072 / 847 / 732
The Astrophysical Journal Letters
Volume 1004, Number L17, Page 13
2026 June
