2020A&A...644A.128S

Aims. In this paper, we study the dense gas of the molecular cloud LDN 1287 (L1287), which harbors a double FU Ori system, an energetic molecular outflow, and a still-forming cluster of deeply embedded low-mass young stellar objects that show a high level of fragmentation.
Methods. We present optical Hα and [SII], and VLA NH₃ (1, 1) and (2, 2) observations with an angular resolution of ∼3.5''. The observed NH₃ spectra have been analyzed with the Hyperfine Structure tool, fitting simultaneously three different velocity components.
Results. The NH₃ emission from L1287 comes from four different structures: a core associated with RNO 1, a guitar-shaped core (the Guitar) and two interlaced filaments (the blue and red filaments) roughly centered toward the binary FU Ori system RNO 1B/1C and its associated cluster. Regarding the Guitar core, there are clear signatures of gas infall onto a central mass that has been estimated to be ∼2.1M_☉. Regarding the two filaments, they have radii of ∼0.03pc, masses per unit length of ∼50M_☉/pc, and are in near isothermal equilibrium. A central cavity is identified, probably related with the outflow and also revealed by the Hα and [SII] emission, with several young stellar objects near its inner walls. Both filaments show clear signs of perturbation by the high-velocity gas of the outflows driven by one or several young stellar objects of the cluster. The blue and red filaments are coherent in velocity and have nearly subsonic gas motions, except at the position of the embedded sources. Velocity gradients across the blue filament can be interpreted either as infalling material onto the filament or rotation. Velocity gradients along the filaments are interpreted as infall motions toward a gravitational well at the intersection of the two filaments.