Oral Presentation
Fragmentation in High-mass star-Forming Clumps
Presenter: Kousuke Ishihara (SOKENDAI/NAOJ)
Hierarchical fragmentation contributes to the formation and evolution of stars. Observationally, high-mass stars are known to form in clustered environments and tend to be composed of multiple systems. Therefore, it is important to understand the fragmentation properties in high-mass star-forming regions. Theoretically, Jeans instability has been suggested to determine characteristic fragmentation scales and mainly thermal or turbulent motion in the parental gas clump contributes to the instability. To reveal the contribution and search for such a characteristic fragmentation scale if existed, we used ALMA 1.3 mm dust continuum observations of 30 high-mass star-forming clumps (M≳200 M⨀, D~1-5 kpc). Our data have spatial resolutions ranging from 200 to 1700 au (~0.''3). We identified 579 cores using the dendrogram algorithm and measured the separation between each core by the Minimum Spanning Tree (MST) technique. We found that the core separation distribution has a peak around 6000 au. The peak separation is roughly comparable to the typical thermal Jeans length of the clumps. We discuss how the peak separation depends on the angular resolution and observational biases. Since the peak separation is significantly shorter than the turbulent fragmentation scale, we conclude that the thermal Jeans fragmentation plays a more important role in determining the clump fragmentation in high-mass star-forming regions.
asiaa.sinica.edu.tw