AI Insight
Astronomers have detected two massive star-forming filaments in the G012.80 protocluster with distinct kinematic behaviors. The R1 filament shows evidence of rotation with a velocity gradient of 10.4 km/s per parsec and minimal star formation, while the R2 filament exhibits signs of gravitational collapse with abundant dense cores and a star formation rate of 55.3 solar masses per million years. This suggests the filaments represent different evolutionary stages, with R1 being younger and still rotating before collapsing, while R2 has already begun efficiently forming stars.
Why it matters
This observation provides direct evidence for how massive star-forming filaments evolve from rotation to collapse, helping astronomers understand the initial conditions and timescales of massive star cluster formation in our galaxy. The contrasting properties of these neighboring filaments offer a rare opportunity to study different stages of the same process in a single system.
arXiv:2510.03447v2 Announce Type: replace
Abstract: (abridged) We aim to characterize kinematic processes in the G012.80 protocluster. We principally focus on the N$_2$H$^+$(1$-$0) emission to trace the dense and cold gas. Additionally, we use lines such as DCN(3$-$2), H41$alpha$, C$^{18}$O(1$-$0), and SiO(5$-$4), as well as continuum maps. We perform a N$_2$H$^+$ hyperfine spectral line fitting to analyze multiple velocity components and spectral parameters. We estimate velocity gradients, column densities, and line-mass profiles for the two main filaments in G012, named R1 and R2. Line-mass profiles follow $lambda$($omega$) = 5660 M$_{odot}$ pc$^{-1}$($omega$/pc)$^{0.30}$ (R1) and $lambda$($omega$) = 6943 M$_{odot}$ pc$^{-1}$($omega$/pc)$^{0.20}$ (R2), which are much larger than those of typical low-mass filaments. R1 and R2 show disparate position-velocity (PV) features. R1 exhibits a transverse velocity gradient of 10.4 kms$^{-1} $pc$^{-1}$ and few dense cores. This gradient is interpreted with a simple rotation toy model, combined with line-mass profile, and corresponds to a rotational timescale of 0.1 Myr. In contrast, R2 exhibits compact velocity structures ($Delta$V < 2 kms$^{-1}$), likely due to collapse, as evidenced by the presence of a comparatively large number of massive cores and protostellar outflows. R2 is forming prestellar and protostellar cores at a rate of 55.3 M$_{odot}$ Myr$^{-1}$, with an efficiency similar to the Orion Integral Shaped Filament (ISF). The R1 filament, in contrast, lacks protostellar cores and only contains a few prestellar cores, resulting in an estimated SFR of 4.2 M$_{odot}$ Myr$^{-1}$, more than an order of magnitude below that of R2. Combining these lines of evidence, we suggest that R1 is younger and still rotating, while R2 has evolved to collapse with a higher SFR. G012 thus hosts filaments at different evolutionary stages.