A centrally concentrated sub-solar-mass starless core in the Taurus L1495 filamentary complex
/ Authors
K. Tokuda, K. Tachihara, K. Saigo, P. Andr'e, Y. Miyamoto, S. Zahorecz, S. Inutsuka, Tomoaki Matsumoto, T. Takashima, M. Machida
and 7 more authors
K. Tomida, K. Taniguchi, Y. Fukui, A. Kawamura, K. Tatematsu, R. Kandori, T. Onishi
/ 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 the Morita array) and the IRAM 30-m telescope in 1.2 mm continuum has identified a centrally concentrated starless condensation with a central H2 volume density of ∼106 cm−3, MC5-N, connected to a narrow (width ∼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 pre-stellar cores. Taking into account a typical core to star formation efficiency for pre-stellar cores (∼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 N2H+ and N2D+ observations using the Nobeyama 45-m telescope have confirmed the high-deuterium fractionation (∼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.
Journal: Publications of the Astronomical Society of Japan
DOI: 10.1093/pasj/psz051