H(alpha) Images of the Cygnus Loop: A New Look at Shock-Wave Dynamics in an Old Supernova Remanant
Abstract
Attention is given to deep H-alpha images of portions of the east, west, and southwest limbs of the Cygnus Loop which illustrate several aspects of shock dynamics in a multiphase interstellar medium. An H-alpha image of the isolated eastern shocked cloud reveals cloud deformation and gas stripping along the cloud's edges, shock front diffraction and reflection around the rear of the cloud, and interior remnant emission due to upstream shock reflection. A faint Balmer-dominated filament is identified 30 arcmin further west of the remnant's bright line of western radiative filaments. This detection indicates a far more westerly intercloud shock front position than previously realized, and resolves the nature of the weak X-ray, optical, and nonthermal radio emission observed west of NGC 6960. Strongly curved Balmer-dominated filaments along the remnant's west and southwest edge may indicate shock diffraction caused by shock wave passage in between clouds.
- Publication:
-
The Astronomical Journal
- Pub Date:
- August 1992
- DOI:
- 10.1086/116267
- Bibcode:
- 1992AJ....104..719F
- Keywords:
-
- H Alpha Line;
- Shock Wave Propagation;
- Supernova Remnants;
- Balmer Series;
- Charge Coupled Devices;
- Cygnus Constellation;
- Radio Emission;
- Shock Fronts;
- Sky Surveys (Astronomy);
- Astrophysics;
- SUPRENOVA REMNANTS;
- ISM: KINEMATICS AND DYNAMICS;
- HII REGIONS;
- ISM: STRUCTURE;
- SHOCK WAVES