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Abstract

Hercules A (3C348) is the fourth brightest extragalactic radio source in the sky at low frequencies. It is optically identified with a 18.5 mag galaxy with redshift z Combining double low line 0.154 located in a faint cluster 1,2. Although discovered as early as 19483, and extensively studied during the 1960s, it was not mapped with high-resolution aperture-synthesis radio telescopes because of its low declination. We report here the first results from extensive observations of Her A made with the Very Large Array (VLA)4 of the National Radio Astronomy Observatory. We find that Her A possesses an unusual jet-dominated morphology instead of the Cygnus-A-like morphology expected for such a powerful radio source. Its two jets are quite different in appearance; one appears to be a continuous twisting jet, while the other suggests repeated ejection of individual plasmons by the central object. The presence of such different morphologies in the same source raises interesting questions concerning the generation and evol ution of extended extragalactic radio sources. Variations in the central engine provide the simplest interpretation for some of the features of this object; the role of environmental effects is less clear.

Original languageEnglish (US)
Pages (from-to)43-45
Number of pages3
JournalNature
Volume308
Issue number5954
DOIs
StatePublished - Dec 1 1984

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extragalactic radio sources
rings
radio astronomy
Very Large Array (VLA)
declination
radio telescopes
twisting
plasmons
ejection
engines
sky
observatories
apertures
galaxies
low frequencies
high resolution
synthesis

All Science Journal Classification (ASJC) codes

  • General

Cite this

Dreher, J. W. ; Feigelson, Eric. / Rings and wiggles in Hercules A. In: Nature. 1984 ; Vol. 308, No. 5954. pp. 43-45.
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abstract = "Hercules A (3C348) is the fourth brightest extragalactic radio source in the sky at low frequencies. It is optically identified with a 18.5 mag galaxy with redshift z Combining double low line 0.154 located in a faint cluster 1,2. Although discovered as early as 19483, and extensively studied during the 1960s, it was not mapped with high-resolution aperture-synthesis radio telescopes because of its low declination. We report here the first results from extensive observations of Her A made with the Very Large Array (VLA)4 of the National Radio Astronomy Observatory. We find that Her A possesses an unusual jet-dominated morphology instead of the Cygnus-A-like morphology expected for such a powerful radio source. Its two jets are quite different in appearance; one appears to be a continuous twisting jet, while the other suggests repeated ejection of individual plasmons by the central object. The presence of such different morphologies in the same source raises interesting questions concerning the generation and evol ution of extended extragalactic radio sources. Variations in the central engine provide the simplest interpretation for some of the features of this object; the role of environmental effects is less clear.",
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Rings and wiggles in Hercules A. / Dreher, J. W.; Feigelson, Eric.

In: Nature, Vol. 308, No. 5954, 01.12.1984, p. 43-45.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Rings and wiggles in Hercules A

AU - Dreher, J. W.

AU - Feigelson, Eric

PY - 1984/12/1

Y1 - 1984/12/1

N2 - Hercules A (3C348) is the fourth brightest extragalactic radio source in the sky at low frequencies. It is optically identified with a 18.5 mag galaxy with redshift z Combining double low line 0.154 located in a faint cluster 1,2. Although discovered as early as 19483, and extensively studied during the 1960s, it was not mapped with high-resolution aperture-synthesis radio telescopes because of its low declination. We report here the first results from extensive observations of Her A made with the Very Large Array (VLA)4 of the National Radio Astronomy Observatory. We find that Her A possesses an unusual jet-dominated morphology instead of the Cygnus-A-like morphology expected for such a powerful radio source. Its two jets are quite different in appearance; one appears to be a continuous twisting jet, while the other suggests repeated ejection of individual plasmons by the central object. The presence of such different morphologies in the same source raises interesting questions concerning the generation and evol ution of extended extragalactic radio sources. Variations in the central engine provide the simplest interpretation for some of the features of this object; the role of environmental effects is less clear.

AB - Hercules A (3C348) is the fourth brightest extragalactic radio source in the sky at low frequencies. It is optically identified with a 18.5 mag galaxy with redshift z Combining double low line 0.154 located in a faint cluster 1,2. Although discovered as early as 19483, and extensively studied during the 1960s, it was not mapped with high-resolution aperture-synthesis radio telescopes because of its low declination. We report here the first results from extensive observations of Her A made with the Very Large Array (VLA)4 of the National Radio Astronomy Observatory. We find that Her A possesses an unusual jet-dominated morphology instead of the Cygnus-A-like morphology expected for such a powerful radio source. Its two jets are quite different in appearance; one appears to be a continuous twisting jet, while the other suggests repeated ejection of individual plasmons by the central object. The presence of such different morphologies in the same source raises interesting questions concerning the generation and evol ution of extended extragalactic radio sources. Variations in the central engine provide the simplest interpretation for some of the features of this object; the role of environmental effects is less clear.

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