http://arxiv.org/abs/2002.05984
We aim to further investigate the fragmentation of star-forming filaments in the X-shape Nebula of the California MC, so as to better understand the exact role of filaments in the early stages of star formation. We applied getsources and getfilaments extraction methods to the multi-wavelength images observed with Herschel. The properties of the filaments and cores were determined from such an analysis. A map of $\rm ^{13}CO (2-1)$ emission from the SMT 10m telescope was also used to constrain the dynamical state of the filaments. We selected 10 filaments with elongation factors $E >4$ and column density contrasts $C>0.5$ from the filamentary network identified with getfilaments. All 10 filaments have roughly the same deconvolved FWHM width, with a median value $0.12\pm 0.03$ pc, independently of their column densities ranging from $< 10^{21}\, {\rm cm}^{-2}$ to $>10^{22}\, {\rm cm}^{-2}$. Two star-forming filaments stand out based on the Herschel data: Filaments~8 and 10 harbor quasi-periodic chains of dense cores with a typical projected core spacing of $\sim$ 0.15 pc. These two filamentary structures have supercritical line masses and are not static. Filament~8 exhibits a prominent transverse velocity gradient, suggesting that it is accreting gas from the parent cloud gas reservoir. The estimated mass accretion rate is $\sim 40\pm10\ M_\odot \ \rm Myr^{-1}\ pc^{-1}$. Filament~10 includes two embedded protostars with outflows and is likely at a later evolutionary stage than filament~8. Our findings support the notion that dense molecular filaments play a crucial role in the star formation process. We suggest that accretion onto the two star-forming filaments, as well as geometrical bending, explains why the observed core spacing along them is significantly shorter than the canonical separation of $\sim \,$4 times the filament width predicted by classical cylinder fragmentation theory.
G. Zhang, P. Andre, A. Menshchikov, et. al.
Mon, 17 Feb 20
8/53
Comments: 9 pages, 9 figures, submitted to A&A