Near-infrared line imaging of NGC 6240: Global shock and nuclear starburst
Abstract
Images of the luminous galaxy NGC 6240 in the H2 v = 1 to 0 S(1) 2.12 micrometers line and the (FeII) 1.64 micrometer line are presented. The images have an angular resolution of approximately = or less than 1 second, and for the H2 line, images in three adjacent 320 km/s wide velocity intervals are presented. The H2 emission extends over approximately 5 kpc and shows a complex morphology and chaotic velocity structure in its outer parts. It is concluded that the H2 emission is generated in large scale shocks resulting from the collision of the interstellar media of the merging galaxies. Line ratios indicate that the shock velocity is at most 40 km/s. It is shown that the shocks in NGC 6240 cannot account for the observed far-IR emission. In contrast to the H2 emission, the (FeII) emission comes from the nuclei of the galaxy and is generated in fast SNR shocks resulting from a nuclear starburst. The high (FeII)/Br-gamma ratio indicates a high iron abundance, probably resulting from efficient processing of the nuclear ISM in the starburst. Other aspects of this study are discussed.
- Publication:
-
NASA STI/Recon Technical Report N
- Pub Date:
- June 1992
- Bibcode:
- 1992STIN...9330641V
- Keywords:
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- Infrared Astronomy;
- Luminous Intensity;
- Near Infrared Radiation;
- Shock Waves;
- Starburst Galaxies;
- Active Galactic Nuclei;
- Interstellar Matter;
- Line Spectra;
- Stellar Spectra;
- Astronomy