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Notes for object Hercules A

11 note(s) found in NED.

1. 2008ApJ...687..899R
Hercules A.-The CDG has extended optical line emission (Tadhunter et al. 1993).
The CDG core is the southeastern of the two surface brightness peaks.

2. 2006ApJS..164..307M
Re:3C 348
This source, also known as Hercules A, is a cluster cD galaxy. 3C 348 is a
double-galaxy system in the process of merging (Sadun & Hayes 1993). The radio
core coincides with the southeastern galaxy. This galaxy has faint dust rings
around the core in this near-infrared image. These rings are discussed in detail
by Baum et al. (1996) based on WFPC2 observations.

3. 2003A&A...403..889T
Re:3C 348
3C 348. From ASCA (1998) and Rosat data (PSPC in 1993, HRI in 1996)
Siebert et al. (1999) detected non-thermal emmsion from the core of this
radio galaxy with very poor determination of the spectral index
({alpha}_x_ = 0.7^+0.7^_-0.3_) and flux {approx}3 x 10^-13^ erg cm^-2^
s^-1^. This corresponds to ~10% of the total extended thermal X-ray
emission. These results have been confirmed by an observation with
BeppoSAX of March 1997 (Trussoni et al. 2001). It is worth noticing that
3C 348 is extremely bright at high energies: the optical core luminosity
is consistent with its radio emission (CCC99), while the X-ray
luminosity is {approx}ten times higher than expected from the
radio/X-ray correlation (Canosa et al. 1999).

4. 2002MNRAS.330..977T
Re:PKS 1648+05
PKS1648+05 (Her A). This powerful radio source, with a morphology
between FRI and FR II, has weak narrow emission lines in its optical
spectrum, and the smallest UV excess of any source in Table 1. The
continuum measurements presented in this paper refer to the brighter of
the two nuclei visible in optical images of the core region. The cause
of the apparent UV excess is unknown.

5. 2000MNRAS.317..120R
Re:3C 348
5.10 3C 348 (z=0.154)
3C 348 is a cluster cD galaxy and one of the most luminous of our sample
at both radio and optical wavelengths. The cluster has a high X-ray
luminosity - Einstein observations (White, Jones & Forman 1997) give
L_X_ = 7.547 +/- 0.134 x 10^44^ erg s^-1^ and a temperature 5.4 keV,
which, from the cluster X-ray/optical correlations of Edge & Stewart
(1991), indicate a richness of at least Abell class 1.
The radio map (Dreher & Feigelson 1984) is asymmetric, with complex
ring structures in the western lobe. The eastern jet is also unusual
(for an FR II source) in producing the most intense emission in a long
hotspot 22-40 arcsec from the nucleus, rather than at the end of the
~ 90 arcsec lobe. Optical VRI imaging (Sadun & Haynes 1993) reveals
3C 348 to be a pair of E/S0 galaxies, of similar luminosity, in an
advanced stage of merging. The south-eastern galaxy corresponds to the
radio nucleus position (Griffith et al. 1995), and shows dust rings on
a Hubble Space Telescope image (de Koff et al. 1996).
In our deep V-band image (Figs 14, 15), 3C 348 is detected by PISA as
a large elongated galaxy (ellipticity = 0.380, PA 1120), aligned with
the radio axis, with a barely resolvable double nucleus. The peak
surface brightness (20.82 V mag arcsec^-2^) is at the south-eastern
nucleus, which contains the radio source. Running 'PISAFIND' with
DEBLEND isolates the south-eastern component, detecting it as a single
galaxy that is rounder (ellipticity = 0.134) but still aligned with the
radio axis (PA 1033).
With a higher detection threshold, the two nuclei could be detected
as separate sources, giving an estimate of the luminosity ratio as
1.0:1.083 (south-eastern:north-western). On the contour plot, the
orientation of the pair (shown by the second highest isophote) is
somewhat anticlockwise of the radio axis, but the outer isophotes again
become aligned. We conclude from this and the nucleus PA that it is the
long axis of the galaxy containing the radio nucleus, rather than the
orientation of the merging pair, that is aligned with the radio axis.
The deep V-band image, in which galaxies can be reliably detected to
V ~ 23, shows many much smaller galaxies near 3C 348, apparently members
of its cluster. Three galaxies (G2, G3 and G4) of similar luminosity
(V = 20.45, 20.25 and 20.40, respectively) and central surface
brightness (~ 22.5 V mag arcsec^-2^), form a line close to the radio
axis. G3 has an obvious double nucleus and coincides with the inwards
end of the brightest radio hotspot. After star-galaxy separation and the
removal of noise images, we detect 13 galaxies to V = 23 within
40 arcsec of the radio nucleus, of which seven are < 20^deg^ from the
radio axis. On the basis of Poisson statistics, the probability of this
occurring by chance is only 2.72 per cent, so there is at least marginal
evidence that the distribution of cluster neighbours is aligned with the
radio axis (see Section 9.2.3).
In our U-band image, much less deep and affected by the high Galactic
extinction, the cluster neighbours are not detected and 3C 348 appears
noisy and fragmented, so that it was necessary to smooth the image
slightly before further analysis. On the smoothed U image (Fig. 16),
3C 348 is detected as an elongated (ellipticity = 0.439) and aligned
(PA 1045) galaxy, much as in the V band. The nuclei are slightly better
resolved than in the V band, and by using the DEBLEND option we obtain
the separation between nuclei and their orientation as 3.19 arcsec and
PA 12377. As in the V band, the galaxy long axis is more closely aligned
with the radio axis than is the pair orientation.

6. 2000ApJS..131...95F
Re:VSOP J1651+0459
J1651+0459 (3C 348, Her A). - No detection: this symmetric double-lobe
radio galaxy is not detected in our VLBA survey. The jet-dominated VLA
structure at 1.4 and 5 GHz is shown by Harvanek & Hardcastle (1998) and
Dreher & Feigelson (1984).

7. 1999MNRAS.306..857C
Re:RX J1651.1+0459
Hercules-A has moderate [O II] and weak [O III] ([O III]/[O II]=0.2)
emitted by one of two diffuse continuum components separated by 3
arcsec (10.5 kpc; Tadhunter et al. 1993).

8. 1998ApJS..119...25H
Re:3C 348
Also known as Hercules A, this source (Fig. 14) has one of the highest
measured low-frequency radio flux densities. We observed this source at
two different epochs. Although LAS/{theta}_MAX_ indicates this source
might be affected by undersampling, the total fluxes in Table 5 agree
well with published values, and there does not seem to be much evidence
for missing flux. This may be a case in which the sum of the angular
sizes of all the components making up the source is larger than
{theta}_MAX_ but all the individual components are still seen by the
array. Our two fluxes also agree with each other (within the errors), as
do our two core fluxes; the data from the two epochs are therefore
combined in the map presented here. The core positions from the two
different observations agree to within 0.04".
This source was previously observed at C band by Dreher & Feigelson
(1984), who remarked on its peculiar jet-dominated morphology for a
source of such high radio power. Our 1.4 GHz map shows a weak core as
well as the strong jets. The extended emission is very symmetric about
the radio axis. Polarization maps show a strong asymmetry in fractional
polarization, with the western lobe being much less strongly polarized
than the eastern one. The fact that the more prominent eastern jet lies
in the more strongly polarized lobe combined with the fact that the
source lies in a cluster with strong X-ray emission has led Gizani &
Leahy (1996, 1998) to treat it as an example of the Laing-Garrington
effect (Laing 1988; Garrington et al. 1988).

9. 1993MNRAS.263.1023M
Re:Hercules A
1648+05 (Her A). A very well-known and unusual radio galaxy
(presumably an FR I) studied by Dreher & Feigelson (1984). We took the
core flux density from Feigelson (private communication).

10. 1993MNRAS.263..999T
Re:PKS 1648+05
1648+05 (Hercules A). This object has two diffuse continuum components
separated by 3 arcsec. Moderate [O II] {lambda}3727 and weak [O III]
{lambda}5007 are detected in one of the two components. Both components
show an absorption-line spectrum typical of early-type galaxies. The
[O II] emission is extended.

11. 1964ApJ...140...35M
Re:3C 348
No. 41.-Partially obscured by star image. Her A is centrally located in very
faint cluster of richness 2, visible on 48-inch E plate, and not on 48-inch 0
plate. All galaxies in this cluster are much fainter than Her A. 200-inch plate
by Minkowski. Redshift by Greenstein (1962).

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