The Molecular Core Associated with HH 25–26: Contraction or Expansion?

Lourdes Verdes‐Montenegro, Paul T. P. Ho
1996 Astrophysical Journal  
We mapped the star formation region HH 25È26 IR in the 1) and (2, 2) transitions using the NH 3 (1, VLA in its D conÐguration. The study has been made with 5A angular resolution and 0.3 km s~1 velocity resolution. As has been seen before, there is an elongated core that lies perpendicular to the molecular NH 3 outÑow as traced in high-velocity CO emission. In this experiment, the core is resolved, showing a NH 3 central cavity and a number of distinct velocity features. Heating is seen at the
more » ... ng is seen at the position where the velocity features overlap spatially, and on the edges of the cavity, which is also seen as a reÑection nebula with evidence for shock excitation. We have also detected what appears to be a new 1.3 cm continuum source on the wall of the cavity, associated with a 2.2 km point source and jetlike structure. It is not clear at this time whether this is a truly continuum emission or high-velocity ammonia emission. The overall kinematics is complicated. A velocity gradient can be seen, together with the signatures for expanding or contracting motions. We consider here two possible models : (a) a disk or ring structure, slowly rotating and contracting, and (b) an expanding cavity.
doi:10.1086/178204 fatcat:bpyl6cqlu5fxli44iyngr7jzdy