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  1. Abstract We present Atacama Large Millimeter Array band 6/7 (1.3 mm/0.87 mm) and Very Large Array Ka-band (9 mm) observations toward NGC 2071 IR, an intermediate-mass star-forming region. We characterize the continuum and associated molecular line emission toward the most luminous protostars, i.e., IRS1 and IRS3, on ∼100 au (0.″2) scales. IRS1 is partly resolved in the millimeter and centimeter continuum, which shows a potential disk. IRS3 has a well-resolved disk appearance in the millimeter continuum and is further resolved into a close binary system separated by ∼40 au at 9 mm. Both sources exhibit clear velocity gradients across theirmore »disk major axes in multiple spectral lines including C 18 O, H 2 CO, SO, SO 2 , and complex organic molecules like CH 3 OH, 13 CH 3 OH, and CH 3 OCHO. We use an analytic method to fit the Keplerian rotation of the disks and give constraints on physical parameters with a Markov Chain Monte Carlo routine. The IRS3 binary system is estimated to have a total mass of 1.4–1.5 M ⊙ . IRS1 has a central mass of 3–5 M ⊙ based on both kinematic modeling and its spectral energy distribution, assuming that it is dominated by a single protostar. For both IRS1 and IRS3, the inferred ejection directions from different tracers, including radio jet, water maser, molecular outflow, and H 2 emission, are not always consistent, and for IRS1 these can be misaligned by ∼50°. IRS3 is better explained by a single precessing jet. A similar mechanism may be present in IRS1 as well but an unresolved multiple system in IRS1 is also possible.« less
    Free, publicly-accessible full text available July 1, 2023
  2. Abstract We present velocity-resolved Stratospheric Observatory for Infrared Astronomy (SOFIA)/upgrade German REceiver for Astronomy at Terahertz Frequencies observations of [O i ] and [C ii ] lines toward a Class I protostar, L1551 IRS 5, and its outflows. The SOFIA observations detect [O i ] emission toward only the protostar and [C ii ] emission toward the protostar and the redshifted outflow. The [O i ] emission has a width of ∼100 km s −1 only in the blueshifted velocity, suggesting an origin in shocked gas. The [C ii ] lines are narrow, consistent with an origin in a photodissociationmore »region. Differential dust extinction from the envelope due to the inclination of the outflows is the most likely cause of the missing redshifted [O i ] emission. Fitting the [O i ] line profile with two Gaussian components, we find one component at the source velocity with a width of ∼20 km s −1 and another extremely broad component at −30 km s −1 with a width of 87.5 km s −1 , the latter of which has not been seen in L1551 IRS 5. The kinematics of these two components resemble cavity shocks in molecular outflows and spot shocks in jets. Radiative transfer calculations of the [O i ], high- J CO, and H 2 O lines in the cavity shocks indicate that [O i ] dominates the oxygen budget, making up more than 70% of the total gaseous oxygen abundance and suggesting [O]/[H] of ∼1.5 × 10 −4 . Attributing the extremely broad [O i ] component to atomic winds, we estimate an intrinsic mass-loss rate of (1.3 ± 0.8) × 10 −6 M ⊙ yr −1 . The intrinsic mass-loss rates derived from low- J CO, [O i ], and H i are similar, supporting the model of momentum-conserving outflows, where the atomic wind carries most momentum and drives the molecular outflows.« less
    Free, publicly-accessible full text available January 1, 2023