A PPMAP analysis of the filamentary structures in Ophiuchus L1688 and L1689

We use the Point Process MAPping (PPMAP) algorithm to reanalyse the Herschel and SCUBA-2 observations of the L1688 and L1689 subregions of the Ophiuchus molecular cloud. PPMAP delivers maps with high resolution (here 14 arcsec, corresponding to similar to 0.01 pc at similar to 140 pc), by using the observations at their native resolutions. PPMAP also delivers more accurate dust optical depths, by distinguishing dust of different types and at different temperatures. The filaments and pre-stellar cores almost all lie in regions with N-H2 greater than or similar to 7 x 10(21) cm(-2) (corresponding to Av greater than or similar to 7). The dust temperature, T, tends to be correlated with the dust opacity index, with low T and low concentrated in the interiors of filaments. The one exception to this tendency is a section of filament in L1688 that falls - in projection - between the two B stars: S1 and HD147889; here T and beta are relatively high, and there is compelling evidence that feedback from these two stars has heated and compressed the filament. Filament FWHM5 are typically in the range 0.10 to 0.15 pc. Most filaments have line-densities in the range 25 to 65 M-circle dot pc(-1). If their only support is thermal gas pressure, and the gas is at the canonical temperature of 10 K, the filaments are highly supercritical. However, there is some evidence from ammonia observations that the gas is significantly warmer than this, and we cannot rule out the possibility of additional support from turbulence and/or magnetic fields. On the basis of their spatial distribution, we argue that most of the starless cores are likely to disperse (rather than evolving to become pre-stellar).

Automated summary

The PPMAP algorithm reanalyzed observations of the L1688 and L1689 subregions of the Ophiuchus molecular cloud, delivering high-resolution maps and more accurate dust optical depths. Most filaments and pre-stellar cores are located in regions with high N-H2 values, with some exceptions influenced by feedback from nearby stars. The study suggests that most starless cores are likely to disperse instead of evolving into pre-stellar cores.