The Extended Component of Centaurus A

Abstract

The strong southern radio source Centaurus A (lAU 13S4A) was one of the first to be identified with an optically observable object. Bolton, Stanley, and Slee (1949) suggested that the radio emission was associated with the peculiar galaxy NGC 5128, and this identification has been strengthened by more recent positional measurements (Mills 1952). NGC 5128 is a most unusual object, appearing to be a spheroidal galaxy transected by a heavy belt of obscuring matter (Baade and Minkowski 1954a; Sersic 1958). Its distance is uncertain, but it is likely to be about 1 megaparsec away (Baade, personal communication).

Observations Of The Carina Nebula (Ngc 3372) At 1410 And 2650 Mc/S

“…The physical characteristics of the nebula, as estimated by Wade (1959) would be altered by the latest estimate of distance and by the higher flux density measurement. Table 2 shows the revised values and the optical measurements quoted by Wade (1959), as well as an additional reference to more recent optical data.…”

“…The galactic emission nebula NGC 3372 was first detected as a radio source by Mills, Little, and Sheridan (1956) during their survey of the southern Milky Way at 85•5 Mc/s. Observations at 1400 Mc/s were carried out by Hindman and Wade (1959) and the significance of these observations in relation to the physical characteristics of the nebula was examined in a companion paper by Wade (1959). The half-power beamwidths at 85•5 and 1400 Mc/s were of the order of 1 0 , so that any conclusions drawn from the radio observations about the structure of the nebula included the effect of appreciable aerial smoothing.…”

“…The diameter of the visible nebula is about 1 0 if the low intensity regions are neglected. Wade (1959) used a distance of 1•4 kpc but the mean of more recent investigations by Faulkner (1963), Feinstein (1963), and Graham (1963) indicates a distance closer to 2•7 kpc.…”

Early Australian Optical and Radio Observations of Centaurus A

“…In a more detailed paper examining the extended component of Centaurus A, Wade (1959) used both 1400 and 85.5 MHz data to subtract the contribution of the central source from the extended source to reveal, for the first time, the double lobe nature of the extended source, which is now commonly associated with active radio galaxies (see Figure 43). …”

Brightness Distribution in Discrete Radio Sources. III. The Structure of the Sources.

“…The extended source h as been s h own to co n sist of two components {Bolton and Clark 1960; Wade 1959) . Recent me asu~ements by Twiss, Carter, and Little (1960) have shown that the central source also h as two components.…”