We present near-infrared and millimetre-line observations of the Tornado nebula (G357.7-0.1). We detected 2.12-μm H2 1-0 S(1) line emission towards the suspected site of interaction with a molecular cloud revealed by the presence of an OH(1720-MHz) maser. The distribution of the H2 emission is well correlated with the non-thermal radio continuum emission from the Tornado, and the velocity of the H2 emission spans over 100 km s-1, which both imply that the H2 emission is shock excited. We also detected millimetre lines from 12CO and 13CO transitions at the velocity of the maser, and mapped the distribution of the molecular cloud in a 2 × 2 arcmin2 region around the maser. The peak of the molecular cloud aligns well with an indentation in the radio continuum distribution of the nebula, suggesting that the shock of the nebula is being decelerated at this location, which is consistent with the presence of the OH(1720-MHz) maser and shocked H 2 emission at that location.
- ISM: clouds
- ISM: individual: tornado nebula, G357.7-0.1
- Shock waves
- Supernova remnants