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Journal Paper

전체
High-resolution ALMA Study of the Proto-brown-dwarf Candidate L328-IRS SCI
  • Chang Won Lee;Gwanjeong Kim;Philip C. Myers;Masao Saito;Shinyoung Kim;Woojin Kwon;A-RAN LYO;Archana Soam;Kim, Mi-Ryang
  • 2018-10-01
  • THE ASTROPHYSICAL JOURNAL 865 2 : 131-1~131-15
This paper presents our observational attempts to precisely measure the central mass of a proto-brown dwarf candidate, L328-IRS, in order to investigate whether L328-IRS is in the substellar mass regime. Observations were made for the central region of L328-IRS with the dust continuum and CO isotopologue line emission at Atacama Large Millimeter/submillimeter Array (ALMA) band 6, discovering the detailed outflow activities and a deconvolved disk structure of a size of ~87 × 37 au. We investigated the rotational velocities as a function of the disk radius, finding that its motions between 130 and 60 au are partially fitted with a Keplerian orbit by a stellar object of ~0.30 M ⊙, while the motions within 60 au do not follow any Keplerian orbit at all. This makes it difficult to lead a reliable estimation of the mass of L328-IRS. Nonetheless, our ALMA observations were useful enough to well constrain the inclination angle of the outflow cavity of L328-IRS as ~66°, enabling us to better determine the mass accretion rate of ~8.9 × 10?7 M ⊙ yr?1. From assumptions that the internal luminosity of L328-IRS is mostly due to this mass accretion process in the disk, or that L328-IRS has mostly accumulated the mass through this constant accretion rate during its outflow activity, its mass was estimated to be ~0.012?0.023 M ⊙, suggesting L328-IRS to be a substellar object. However, we leave our identification of L328-IRS as a proto-brown dwarf to be tentative because of various uncertainties, especially regarding the mass accretion rate.