A centrally concentrated sub-solar mass starless core in the Taurus L1495 filamentary complex

Abstract

The formation scenario of brown dwarfs is still unclear because observational studies to investigate its initial condition are quite limited. Our systematic survey of nearby low-mass star-forming regions using the Atacama Compact Array (aka Morita array) and the IRAM 30 m telescope in 1.2 mm continuum has identified a centrally concentrated starless condensation with a central H${}_2$ volume density of $\sim$10${}^6$ cm${}^{-3}$, MC5-N, connected to a narrow (width $\sim$0.03 pc) filamentary cloud in the Taurus L1495 region. The mass of the core is $\sim$0.2-0.4 $M_{\odot }$, which is an order of magnitude smaller than typical low-mass prestellar cores. Taking into account a typical core to star formation efficiency for prestellar cores ($\sim$20%-40%) in nearby molecular clouds, brown dwarf(s) or very low-mass star(s) may be going to be formed in this core. We have found possible substructures at the high-density portion of the core, although much higher angular resolution observation is needed to clearly confirm them. The subsequent N${}_2$H${}^{+}$ and N${}_2$D${}^{+}$ observations using the Nobeyama 45 m telescope have confirmed the high-deuterium fractionation ($\sim$30%). These dynamically and chemically evolved features indicate that this core is on the verge of proto-brown dwarf or very low-mass star formation and is an ideal source to investigate the initial conditions of such low-mass objects via gravitational collapse and/or fragmentation of the filamentary cloud complex.

23 pages, 4 figures, PASJ accepted for publication

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Cited by in corpus (8)

• FRagmentation and Evolution of dense cores Judged by ALMA (FREJA). I (Overview). Inner $\sim$1000 au structures of prestellar/protostellar cores in Taurus
• A low-velocity bipolar outflow from a deeply embedded object in Taurus revealed by the Atacama Compact Array
• ALMA ACA and Nobeyama observations of two Orion cores in deuterated molecular lines
• 3D Radiative Transfer Modelling and Virial Analysis of Starless Cores in the B10 Region of the Taurus Molecular Cloud
• ALMA observations of the early stages of substellar formation in the Lupus 1 and 3 molecular clouds
• Extended and Compact Ortho-H${}_2$D${}^{+}$ Structures Close to the Moment of Star-Formation: Evidence from ALMA-ACA Observations in Taurus
• ALMA 0.1 pc View of Molecular Clouds Associated with High-Mass Protostellar Systems in the Small Magellanic Cloud: Are Low-Metallicity Clouds Filamentary or Not?
• NOEMA complementarity with NIKA2