3C 381


Basic Data
S178 Alpha FR Class ID Spectrum Best z mag. LAS lg P178 D
18.10.81IICD Gal0.1605R(c) = 16.86 74.0025.87 177.3


Size: 80.0 × 80.0 arcsec²
LUT: Logarithmic
Beam: 1.25 arcsec
Frequency: 1477 MHz
Method: CLEAN ՘>1.25
Telescope: VLA A+B
Credits: Leahy & Perley (1991)

The host galaxy is surrounded by a very large and bright emission-line nebula (McCarthy et al. (1995)), which in the centre is roughly aligned with the radio axis. It may affect the radio structure: the bright ridge crossing the northern lobe is sited just beyond a filament of emission-line gas, and may represent compression of material outflowing from the hotspot by this obstacle. An HST image is given by de Koff et al. (1996); the galaxy is round and featureless apart from the elongated emission-line feature which is bright enough to be detected in the continuum bandpass.

The low-resolution image on the "Other images" page shows that near the centre both lobes show faint, rotationally symmetric distortions away from the nucleus. A high-resolution image showing details of the very asymmetric hotspots is given by Hardcastle et al. (1997).

There is a companion galaxy 5.5 arcsec to the east, projected within the faint extension of the northern lobe. Roche & Eales (2000) claim that the two galaxies have tidal distortion and hence are closely interacting; however their images do not shown this very clearly. The radio lobes show no sign interacting with the companion. The galaxies are members of a cluster.

3C 381 is often listed as a broad-line radio galaxy, on the basis of an unpublished spectrum by Grandi & Osterbrock (1978). This has been controversial because the radio structure does not show the quasar-like features (strong core and one-sided jet) that are common in most BLRG, and expected according to unified schemes. As discussed by Dennett-Thorpe et al. (2000), a likely explanation is that it is a case like 3C 234, at an intermediate angle to the line of sight so that the broad lines are highly reddened but just detectable.

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