Hercules A

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Coordinates: Sky map 16h 51m 08.15s, +04° 59′ 33.32″

Hercules A
A Multi-Wavelength View of Radio Galaxy Hercules A.jpg
Visible light image obtained by Hubble superposed with a radio image taken by the VLA.
Observation data (J2000 epoch)
Right ascension16h 51m 08.15s
Declination+04° 59′ 33.32″
Distance2100 Mly
(643.9 Mpc)
TypecD; E3
Other designations
Herc A , 3C 348
See also: Galaxy, List of galaxies

Hercules A is a bright astronomical radio source within the vicinity of the constellation Hercules[1] corresponding to the galaxy 3C 348.


During a survey of bright radio sources in the mid-20th century, astronomers found a very bright radio source in the constellation Hercules. The radio source is strongest in the middle range frequency and emits synchrotron radiation, suggesting the source of radio emission may be gravitational interaction. In 1959, astronomers from the Radio Astronomy Group (later the Cavendish Astrophysics Group) detected the radio source using the Cambridge Interferometer of the Cavendish Observatory in Cambridge University in United Kingdom, including it in the Third Cambridge Catalogue of Radio Sources (3C) as 3C 348, the 348th object detected by the survey.



The galaxy, 3C 348, is a supergiant elliptical galaxy. It is classified as type E3 to E4 of the updated Hubble-de Vaucouleurs extended galaxy morphological classification scheme. Little else is known about the galaxy.

3C 348, the galaxy at the image center, appears to be a relatively normal elliptical galaxy in visible light. When imaged in radio waves, however, plasma jets over one million light years long appear. Detailed analyses indicate that the galaxy is actually over 1,000 times more massive (approx. 1015 solar masses) than our Milky Way Galaxy, and the central black hole is nearly 1,000 times more massive (approx. 4 billion solar masses) than the black hole at our Milky Way's center, one of the largest known. The physics that creates the jets is poorly understood, with a likely energy source being matter ejected perpendicular to the accretion disc of the central black hole.[2]

See also[edit]


  1. ^ "A Multi-Wavelength View of Radio Galaxy Hercules A". NASA.
  2. ^ Nemiroff, R.; Bonnell, J., eds. (5 December 2012). "Plasma Jets from Radio Galaxy Hercules A". Astronomy Picture of the Day. NASA.Portions of this public domain text are used here.