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Astron. Astrophys. 337, 69-79 (1998)

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2. General source properties

2.1. Optical properties

The radio source 0710+439 has been identified (Peacock et al. 1981) with a galaxy of r magnitude of [FORMULA]. The emission-line redshift of the galaxy is [FORMULA] (Lawrence et al. 1996). At this redshift 1 mas = 3.6 [FORMULA] pc assuming [FORMULA] = 100 h km s-1 Mpc-1 and [FORMULA] = 0.5. The optical spectrum (Lawrence et al. 1996) shows absorption lines characteristic of an evolved stellar population and an optical continuum shape typical of an elliptical galaxy without any evidence for a nonstellar component.

2.2. Radio properties

0710+439 has high radio luminosity ([FORMULA] = [FORMULA] erg s-1 Hz-1; Wilkinson et al. 1994). The flux density is very weakly polarised ([FORMULA] at 5 GHz) and the observed variations of the flux are not statistically significant (Aller et al. 1992). The total angular size of the source is 24.1 mas, which corresponds to a projected linear size of 86.8 [FORMULA] pc. The source has been mapped by VLBI at several frequencies i.e. 1.6, 5, 10.7, and 15 GHz. These observations showed the overall triple structure of the source. Despite having three components this source was provisionally classified as a compact double based on the fact that more than 80% of the emission came from two almost equally bright components (Pearson & Readhead 1988). Conway et al. (1992) argued that the two outer components were hotspots and minilobes, while the centre of activity was associated with the middle component, based on its compactness, spectrum and weak flux density variability. Recent multi-frequency observations (Taylor et al. 1996) reveal a compact component with a strongly inverted spectrum at the southern end of the middle component, suggesting that the true centre of activity lies there.

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© European Southern Observatory (ESO) 1998

Online publication: August 6, 1998