The Dense Gas Structures Around MMS 2/OMC-3 Traced by C${}^{18}$O Emission

Abstract

We report the Atacama Large Millimeter/submillimeter Array observations of 1.3 mm continuum, C${}^{18}$O ($J=2$$-$$1$), and N${}_2$D${}^{+}$ ($J=3$$-$$2$) toward the millimeter multi-system MMS 2 in the Orion Molecular Cloud-3 region, at an angular resolution of 1.59" ($\sim$620 au). MMS 2 is in the flat-spectrum phase, with its protostars in the late stage of the main accretion phase. We detect the centrally condensed structures traced by C${}^{18}$O emission associated with the 1.3 mm continuum sources MMS 2-North and MMS 2-South, which are spatially resolved and unresolved, respectively. The estimated diameter and mass of the centrally condensed structure associated with MMS 2-North are 1.64" ($\sim$640 au) and 3.0$\times$10${}^{-4}$M${}_{\odot }$, respectively. We also detect an extended structure traced by C${}^{18}$O emission associated the circumbinary envelope at scale of 5.70" ($\sim$2240 au) with an estimated gas mass of 1.4$\times$10${}^{-2}$$M_{\odot }$. In addition, we detect a filamentary structure traced by N${}_2$D${}^{+}$ emission to the south of MMS 2, which is spatially offset from the C${}^{18}$O emission. This offset may be attributed to the influence of the warm surrounding environment.

19 pages, 7 figures, accepted for publication in Astrophysical Journal