[NCTS Astrophysics Lunch Seminar] Quantification of Sub-parsec Scale Dense Core Arrangements with Fragmentation Number

Title:Quantification of Sub-parsec Scale Dense Core Arrangements with Fragmentation Number
Time:2023/10/27 (Fri.) 12:10
4F Lecture Hall, Cosmology Hall, NTU
Webex online (Meeting number:2563 282 1613 / Password:TG23 (8423 from phones and video systems))

As high-resolution observations reveal dense cores (~ 10^{5-6} cm^{-3}, ~ 0.1 - 0.01 pc) embedded in diffuse clumps (~ 10^{4} cm^{-3},  ~ 1 pc), the link between the two scales is actively studied, especially how different environments regulate clump fragmentation.
In this talk, I will introduce a new algorithm to generate a score, the fragmentation number (F_N), for the spatial distribution of these sub-parsec dense cores in star formation regions. F_N only requires the clump intensity map and a core-finder algorithm, and can be used to study the relation between the two scales.
I will first illustrate the properties of F_N through experiments, which show that F_N is higher when the brighter cores are more separate and aligned, which agrees with our visual inspection.
I then use F_N to analyze ALMA Survey of 70 \mu m Dark High-mass Clumps in Early Stages (ASHES) 1.3 mm dust continuum emission maps. The results demonstrate that F_N can measure the fragmentation from the identified cores, but the choice of parameters for the core-finder criteria can result in different interpretations.
I also find that F_N is correlated with core formation efficiency (CEF), showing that "clustered fragmentation" clumps have higher efficiency at transporting mass into cores. However, I do not find other significant correlations with the clump parameters, except for the intrinsic properties of F_N.
Thus, more clump parameters, such as magnetic field strength or observation data with a wider range of evolutionary stages, are needed for a more comprehensive understanding.
For my next step, I am using the ideal MHD code (GAMER) to study the fragmentation under different environments and how it changes with the clump evolution.

*registration (for onsite) will be closed at 10/25(Wed.)12:00 noon.

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