High Angular Resolution , Sensitive CS J = 2 − 1 and J = 3 − 2 Imaging of the Protostar L 1551 NE : Evidence for Outflow - Triggered Star Formation ? 1

High angular resolution and sensitive aperture synthesis observations of CS (J = 2−1) and CS (J = 3−2) emissions toward L1551 NE, the second brightest protostar in the Taurus Molecular Cloud, made with the Nobeyama Millimeter Array are presented. L1551 NE is categorized as a class 0 object deeply embedded in the red-shifted outflow lobe of L1551 IRS 5. Previous studies of the L1551 NE region in CS emission revealed the presence of shell-like components open toward L1551 IRS 5, which seem to trace low-velocity shocks in the swept-up shell driven by the outflow from L1551 IRS 5. In this study, significant CS emission around L1551 NE was detected at the eastern tip of the swept-up shell from Vlsr = 5.3 km s to 10.1 km s, and the total mass of the dense gas is estimated to be 0.18 ± 0.02 M⊙. Additionally, the following new structures were successfully revealed: a compact disklike component with a size of ≈ 1000 AU just at L1551 NE, an arc-shaped structure around L1551 NE, open toward L1551 NE, with a size of ∼ 5000 AU, i.e., a bow shock, and a distinct velocity gradient of the Based on the observations made at the Nobeyama Radio Observatory (NRO), which is a branch of the National Astronomical Observatory, an interuniversity research institute operated by the Ministry of Education, Science, Sports, Culture, and Technology. Department of Astronomical Science, The Graduate University for Advanced Studies, Osawa 2-21-1, Mitaka, Tokyo, 181-8588, Japan National Astronomical Observatory of Japan, Osawa 2-21-1, Mitaka, Tokyo, 181-8588, Japan; [email protected], [email protected] Institute of Space and Astronautical Science, Yoshinodai 3-1-1, Sagamihara, Kanagawa, 229-8510, Japan; [email protected] Institute of Astrophysics & Planetary Sciences, Ibaraki University, Bunkyo 2-1-1, Mito, Ibaraki, 3108512, Japan; [email protected]