ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP): Detection of extremely high density compact structure of prestellar cores and multiple substructures within

Abstract

Prestellar cores are self-gravitating dense and cold structures within molecular clouds where future stars are born. They are expected, at the stage of transitioning to the protostellar phase, to harbor centrally concentrated dense (sub)structures that will seed the formation of a new star or the binary/multiple stellar systems. Characterizing this critical stage of evolution is key to our understanding of star formation. In this work, we report the detection of high density (sub)structures on the thousand-au scale in a sample of dense prestellar cores. Through our recent ALMA observations towards the Orion molecular cloud, we have found five extremely dense prestellar cores, which have centrally concentrated regions $\sim$ 2000 au in size, and several $10^7$ $c{m}^{-3}$ in average density. Masses of these centrally dense regions are in the range of 0.30 to 6.89 M${}_{\odot }$. {\it For the first time}, our higher resolution observations (0.8${}^{\prime \prime }\sim$ 320 au) further reveal that one of the cores shows clear signatures of fragmentation; such individual substructures/fragments have sizes of 800 -1700 au, masses of 0.08 to 0.84 M${}_{\odot }$, densities of $2-8\times 10^7$ $c{m}^{-3}$ and separations of $\sim 1200$ au. The substructures are massive enough ($\gtrsim 0.1M_{\odot }$) to form young stellar objects and are likely examples of the earliest stage of stellar embryos which can lead to widely ($\sim$ 1200 au) separated multiple systems.

Published in The Astrophysical Journal Letters (ApJL)

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Cited by in corpus (14)

• ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP): A Hot Corino Survey toward Protostellar Cores in the Orion Cloud
• Multi-line observations of CH${}_3$OH, c-C${}_3$H${}_2$ and HNCO towards L1544: Dissecting the core structure with chemical differentiation
• A Low-mass Cold and Quiescent Core Population in a Massive Star Protocluster
• ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP): How do dense core properties affect the multiplicity of protostars?
• Density Structure of Centrally Concentrated Prestellar Cores from Multi-scale Observations
• Molecular Cloud Cores with High Deuterium Fractions: Nobeyama Mapping Survey
• Nobeyama Survey of Inward Motions toward Cores in Orion Identified by SCUBA-2
• GGCHEMPY: A pure Python-based gas-grain chemical code for efficient simulation of interstellar chemistry
• An ALMA search for substructure and fragmentation in starless cores in Orion B North
• Magnetic Spirals in Accretion Flows Originated from Misaligned Magnetic Field
• ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP): A forming quadruple system with continuum `ribbons' and intricate outflows
• The factors that influence protostellar multiplicity I: Gas temperature, density, and mass in Perseus with Nobeyama
• Synthetic ngVLA line observations of a massive star-forming cloud
• ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP): Deriving Inclination Angle and Velocity of the Protostellar Jets from their SiO Knots