Figure 6(a) shows the 1.3 mm continuum and C18O(J = 2–1) distribution around the Papillon Nebula. The extended 1.3 mm continuum emission around the Papillon Nebula YSO roughly agrees with the distribution of Hα emission and has no counterparts of molecular gas, indicating that the continuum emission seems to be dominated by free–free emission from the ionized gas (see also Paper I). On the other hand, the filamentary dust clumps along the C18O emission, a tracer of cold/dense molecular gas, are considered to be dominated by thermal dust emission. Two major local maxima, hereafter MMS-1 and MMS-2, are found in the 1.3 mm continuum image in Figures 6(a)–(c). Because we detected extended emission in 1.3 mm and C18O along the north–south direction, the two sources are considered to be dense cores embedded in the filamentary cloud. The peak column densities and total masses of both sources deduced from the 1.3 mm continuum emission are ∼1 × 1024 cm−2, and ∼2 × 102 M⊙, respectively, with an assumption of the dust emissivity, 





 of 1 cm2 g−1 for protostellar envelopes (e.g., Ossenkopf & Henning 1994), a dust-to-gas ratio of 3.0 × 10−3 (Herrera et al. 2013; Gordon et al. 2014), and a uniform dust temperature of 20 K, which is typically adapted/estimated for galactic high-mass star-forming dust clumps (e.g., Urquhart et al. 2014; Yuan et al. 2017). Note that the core boundaries deriving their total masses were set as the 30% intensity level of each continuum peak to avoid contaminations from the parental filamentary clouds. Although these sources were not cataloged as point sources in the infrared observations (e.g., Chen et al. 2010; Carlson et al. 2012), their detection in the 1.3 mm is strongly suggestive of their protostellar nature. We have identified outflow wings that have a velocity span of ∼30 km s−1 in 12CO(J = 2–1) toward MMS-1 and MMS-2. Figures 6(b)–(e) show the distributions and the line profiles of the outflow wings. We extracted the spectra and chose the velocity ranges using the following procedure. We defined the outer boundaries of the outflow spectra (i.e., maximum relative velocity) above the 2σ level of the velocity-smoothed spectra with a smoothing kernel of 9 ch (=1.8 km s−1). We extracted the spectra at positions ∼1″ away from the millimeter sources in the east direction as the references without the outflow contaminations and defined the velocities below 2σ intensity levels as the inner edge of the outflow spectra (see Figures 6(d) and (e)). The outflow and YSO properties are listed in Table 2. The size of the outflow is as small as ∼0.1 pc, and escaped detection with our lower-resolution study (Paper I). It is likely that the launching points of the outflows coincide with the 1.3 mm continuum peaks. Because the positional offsets between the blueshifted and redshifted lobes are quite small toward MMS-1 and MMS-2, the outflow orientations may be close to pole-on or very small. The dynamical time (td) of the outflows is roughly estimated to be 104 yr from a ratio of 0.1 pc/20 km s−1. We roughly estimated the mechanical forces of the outflow lobes (Fout) using the following equation: Fout = MoutVout/td (e.g., Beuther et al. 2002), where Vout and Mout are the outflow velocity and mass, respectively. The estimated Fout is ∼10−3–10−2 M⊙ km s−1 yr−1, depending on the assumption of the outflow inclination angle (i = 30°–70°). The Fout and the envelope mass derived from millimeter dust continuum observations are consistent with those of Galactic high-mass protostars (e.g., Beuther et al. 2002) and the N159W-South region (TFH19). A large amount of the surrounding gas with a mass of ∼102 M⊙ and the nondetection of infrared emission suggest that MMS-1 and MMS-2 are in an extremely young phase of high-mass star formation, with an age of ≲104 yr. We note that the Papillon Nebula YSO is more evolved than the two sources; however, the age is as young as ∼0.1 Myr (Paper I) judging from the combination of the spectral energy distribution fitting using the Spitzer/Herschel data and the compactness of the H i region (see also Chen et al. 2010). Although certain time differences are found, the three high-mass protostellar systems with separations of ∼1–2 pc are formed within the order of ∼0.1 Myr. We discuss the possible processes of high-mass star formation taking place in the N159E-Papillon region in Section 4.1.
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