3C 349


Basic Data
S178 Alpha FR Class ID Spectrum Best z mag. LAS lg P178 D
14.50.74IICD Gal0.205R(c) = 17.84 85.3025.99 244.3


Size: 76.8 × 76.8 arcsec²
LUT: Logarithmic
Beam: 1.2 arcsec
Frequency: 1477 MHz
Method: CLEAN/VTESS’ėˇ>1.2
Telescope: VLA A+B
Credits: Leahy & Perley (1991)

The postion of the host galaxy is marked with the red cross; it is coincident with the radio core. Just south-east of the core is a compact but rather faint peak, not clearly visible with our LUT because of the low contrast. This is the only sign of a jet: at higher resolution Hardcastle et al. (1997) find it to be extended toward the south-east hotspot.

The two ends of this source are a study in contrasts. To the north-west, the lobe shows a slight bottleneck structure (cf. 3C 184.1), and the hotspot at the end is resolved in our image. To the south-east the lobe expands and brightens just before the hotspot, giving a mushroom-cap structure. Hardcastle et al. show that the sharp brightness jump also corresponds to a sharp change in radio spectrum, from relatively flat in the cap to steeper in the main bridge (there is a similar spectral edge halfway along the northern bridge). The south-east hotspot is extremely bright and compact, with its outer edge still sharp even at Hardcastle et al.'s 0.25 arcsec resolution.

Possible reasons for the mushroom-cap structure are essentially the inverse of the ones suggested for bottlenecks (see comments on 3C 184.1); for instance the jet may have encountered a relatively dense clump, or the engine state may have changed to produce a beam with more energy but lower density.

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Page created: 2009 Apr 2 14:16:43
J. P. Leahy