Fibers in the NGC 1333 proto-cluster

Abstract

Are the initial conditions for clustered star formation the same as for non-clustered star formation? To investigate the initial gas properties in young proto-clusters we carried out a comprehensive and high-sensitivity study of the internal structure, density, temperature, and kinematics of the dense gas content of the NGC1333 region in Perseus, one of the nearest and best studied embedded clusters. The analysis of the gas velocities in the Position-Position-Velocity space reveals an intricate underlying gas organization both in space and velocity. We identified a total of 14 velocity-coherent, (tran-)sonic structures within NGC1333, with similar physical and kinematic properties than those quiescent, star-forming (aka fertile) fibers previously identified in low-mass star-forming clouds. These fibers are arranged in a complex spatial network, build-up the observed total column density, and contain the dense cores and protostars in this cloud. Our results demonstrate that the presence of fibers is not restricted to low-mass clouds but can be extended to regions of increasing mass and complexity. We propose that the observational dichotomy between clustered and non-clustered star-forming regions might be naturally explained by the distinct spatial density of fertile fibers in these environments.

Gravitational collapse of the OMC-1 region

“…We observed this region at the frequency of the N 2 H + (1−0) line (93173.764 MHz, Pagani et al 2009) using the EMIR receiver connected to the VESPA spectrometer achieving an effective spectral resolution of 0.06 km s −1 . The observations were carried out in Position-Switching mode using an OFF position at approximately 1 degree from the center of our maps with no detected emission above 0.02 K. Calibrations were carried out every 15 min as well as pointing and focus every 1.5−2.0 h. The reduction strategy, baseline subtraction, and main beam calibration follow the reduction scheme presented by Hacar et al (2017). Our final map covers a total area of ∼420 arcmin 2 obtained from a mosaic with different tiles of 200 × 200 and 100 × 100 arcsec 2 each.…”

“…This information is obtained from the hyperfine fit of the individual spectra following the same multi-line fitting strategy presented by Hacar et al (2017). This fitting procedure provides a full description of the gas emission in terms of the mean gas velocity along the line-of-sight (i.e., velocity centroids), the FWHM, line emission properties (i.e., intensity and opacity), and line multiplicity (or number of components) at each position in our map.…”

How Do Stars Gain Their Mass? A JCMT/SCUBA-2 Transient Survey of Protostars in Nearby Star-forming Regions

“…However, the filament width may be influenced by telescope resolution, since JCMT Gould Belt images of the Orion A molecular cloud revealed that many filaments are significantly narrower than 0.1 pc (Salji et al 2015;Panopoulou et al 2017). Many filaments appear to have significant substructure along both their long and short axes and may be bundles of subfilaments or fibers, which have been rarely analyzed in detail but may hold important clues to the stability and nature of the filaments (Contreras et al 2013;Hacar et al 2013Hacar et al , 2017. Deeper SCUBA-2 observations with JCMT resolution will better reveal faint extended substructure, thereby extending the range of filaments to those that are lower mass and less dense, and will allow for a robust measurement of filament widths.…”

The Dense-gas Mass versus Star Formation Rate Relation: A Misleading Linearity?

“…In the L1495/B213 Taurus region and the Perseus NGC1333 protocluster, most Class 0/I objects are observed in 'fibers', also refered as 'velocity-coherent filaments' (Hacar et al 2013;Hacar, Tafalla & Alves 2017).…”

“…These fragments are not resolved by the adopted clump density profile, ρ clump (r). To do so, we use the ratio between the mass of N 2 H + -mapped gas and the mass in Class 0/I objects in the Taurus L1495/B213 region, which is found to be around 10 by Hacar, Tafalla & Alves (2017). Applying this correction (Eq.…”