HESS J1912+101 is a shell-like TeV source that has no clear counterpart in multiwavelength. Using CO and H i data, we reveal that V LSR ∼ +60 km s −1 molecular clouds (MCs), together with shocked molecular gas and high-velocity neutral atomic shells, are concentrated toward HESS J1912+101. The prominent wing profiles up to V LSR ∼ +80 km s −1 seen in 12 CO (J=1-0 and J=3-2) data, as well as the high-velocity expanding H i shells up to V LSR ∼ +100 km s −1 , exhibit striking redshiftedbroadening relative to the quiescent gas. These features provide compelling evidences for largescale perturbation in the region. We argue that the shocked MCs and the high-velocity H i shells may originate from an old supernova remnant (SNR). The distance to the SNR is estimated to be ∼ 4.1 kpc based on the H i self-absorption method, which leads to a physical radius of 29.0 pc for the ∼(0.7-2.0)×10 5 years old remnant with an expansion velocity of > ∼ 40 km s −1 . The +60 km s −1 MCs and the disturbed gas are indeed found to coincide with the bright TeV emission, supporting the physical association between them. Naturally, the shell-like TeV emission comes from the decay of neutral pions produced by interactions between the accelerated hadrons from the SNR and the surrounding high-density molecular gas.

We present high angular resolution observations of the Class 0 protostar IRAM 04191+1522, using the Submillimeter Array (SMA). The SMA 1.3 mm continuum images reveal within IRAM 04191+1522 two distinct sources with an angular separation of 7.8 ± 0.2 ′′ . The two continuum sources are located in the southeast-northwest direction, with total gas masses of ∼ 0.011 M ⊙ and ∼ 0.005 M ⊙ , respectively. The southeastern source, associated with an infrared source seen in the Spitzer images, is the well-known Class 0 protostar with a bolometric luminosity of ∼ 0.08 L ⊙ . The newly-discovered northwestern continuum source is not visible in the Spitzer images at wavelengths from 3.6 to 70 µm, and has an extremely low bolometric luminosity (< 0.03 L ⊙ ). Complementary IRAM N 2 H + (1-0) data that probe the dense gas in the common envelope suggest that the two sources were formed through the rotational fragmentation of an elongated dense core. Furthermore, comparisons between IRAM 04191+1522 and other protostars suggest that most cores with binary systems formed therein have ratios of rotational energy to gravitational energy β rot > 1%. This is consistent with theoretical simulations and indicates that the level of rotational energy in a dense core plays an important role in the fragmentation process.

We report the global properties recovered by an ongoing CO survey of the Milky Way Imaging Scroll Painting (MWISP) toward the Galactic outskirts. Our results are also compared to those extracted by a uniform decomposition method from the CfA 1.2 m CO survey and the FCRAO 14 m outer Galaxy survey (OGS). We find that more extended and unseen structures are present in the MWISP data. The total flux across the disk recovered by the MWISP survey is 1.6 times larger than those recovered by the CfA survey and OGS in the case of the same resolution. The discrepancies are scaling with distance. For example, in the outermost Outer Scutum–Centaurus arm, the flux ratios for MWISP to CfA and MWISP to OGS increase up to 43.8 and 7.4, respectively. Nonetheless, the census of molecular gas in our Galaxy is still far from complete by the MWISP, with flux completeness of <58%. The total mass ratios of the tabulated molecular clouds between different surveys are similar to the CO flux ratio. The application of these ratios to the total H2 mass of our Galaxy yields a correction factor of at least 1.4, meaning that the H2 mass of our Galaxy should be at least 40% more massive than previously determined. Including the completeness correction, an even more significant fraction of the matter should be contributed by baryonic matter. The mass spectrum in the outer Galactic plane is better described by a nontruncating power law with γ = −1.83 ± 0.05 and an upper mass of M 0 = (1.3 ± 0.5) × 106 M ☉.

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