Centaurus A (NGC 5128)

NGC 5128
NGC 5128: Centaurus A Galaxy; TEC APO 140 ED Refraktor, f=980 mm; SBIG STT-8300 SG/AO-8T; Losmandy G11 + FS2; L 1x1 35x5 min, R 2x2 10x5 min, G 2x2 12x5 min, B 2x2 14x5 min; Namibia; © 2013 Hansjörg Wälchli [46]
NGC 5128
NGC 5128: Radio galaxy in Centaurus; TEC 140 ED F/7 APO refractor at f/7 with TEC field flattener; SBIG STT-8300M; 44x5 min; Namibia, Kiripotib Astrofarm, 1350 m ASL; © 3.-11. 7. 2013 Manuel Jung [45]
NGC 5128
NGC 5128: Centaurus A Galaxy; Hypergraph 400 mm f/8.3; STL11000M; L 70 min, R 80 min, G 70 min, B 70 min; Astrofarm Tivoli, Namibia, 1345 m ASL; © 2011 Eduard von Bergen, Hansjörg Wälchli [29]

History

The galaxy NGC 5128 was discovered by Scottish astronomer James Dunlop on 29 April 1826 using the self-built 9-inch reflector at Parramatta observatory near Sydney, Australia. Based on six observation he recorded it as D 482 and described the object as follows: «A very singular double nebula, about 2.5' long and 1' broad, a little unequal: there is a pretty bright small star in the south extremity of the southernmost of the two, resembling a bright nucleus: the northern and rather smaller nebula is faint in the middle, and has the appearance of a condensation of the nebulous matter near each extremity. These two nebulae are completely distinct from each other, and no connection of the nebulous matters between them. There is a very minute star in the dark space between the preceding extremities of the nebula; they are extended in the parallel of the equator nearly.» [50]

John Herschel observing from South Africa he recored this object as h 3501 and wrote for sweep 454 (1 June 1834): «A most wonderful object; a nebula very bright; very large; little extended; very gradually much brighter middle; of an elliptic figure, cut away in the middle by a perfectly definite straight cut 40" broad; pos = 120.3; dimensions of the nebula 5' by 4'. The internal edges have a gleaming light like the moonlight touching the outline in a transparency.» On sweep 455 (3 June 1834) he wrote: «[Two nebulae, or two portions of one separated by a division or cut.] The cut is broad and sharp. The two nebulae are very nearly alike. Perhaps the slit is larger towards the north preceding end, where there is a star between them. There is certainly a very feeble trace of nebula, an island as it were, running from this star between the sides of the slit.» [11]

In Halton Arp's 1966 Atlas of Peculiar Galaxies, NGC 5128 is listed as Arp 153 in group #153-150 for an example of a disturbed galaxy with interior absorption. [199]

NGC 5128
NGC 5128: Colour composite image revealing the lobes and jets emanating from the active galaxy’s central black hole. 870-micron submillimetre (orange) from LABOCA on APEX; X-ray (blue) from Chandra X-ray; Visible light from 2.2 m telescope located at La Silla, Chile; © 2009 ESO, NASA [659]

Physical Properties

Centaurus A (NGC 5128) is an elliptical, active radio galaxy, our nearest giant galaxy, at a distance of about 13 million light-years. It is currently merging with a companion spiral galaxy, which results in areas of intense tar formation. It has a very active and highly luminous central region, caused by the presence of a supermassive black hole. It is the source of strong radio and X-ray emission radiating from the jets and lobes emanating from the central black hole. The jets are travelling at approximately half the speed of light. A ring of dust is encircling the galaxy. [659]

Revised+Historic NGC/IC Version 22/9, © 2022 Dr. Wolfgang Steinicke [277]
Designation NGC 5128
Type Gx (S0/P)
Right Ascension (J2000.0) 13h 25m 29.0s
Declination (J2000.0) -43° 00' 58"
Diameter 25.7 × 20 arcmin
Photographic (blue) magnitude 7.8 mag
Visual magnitude 6.8 mag
Surface brightness 13.5 mag·arcmin-2
Position Angle 35°
Redshift (z) 0.001825
Distance derived from z 7.71 Mpc
Metric Distance 3.660 Mpc
Identification, Remarks h 3501; GC 3525; ESO 270-9; MCG -7-28-1; Arp 153; IRAS 13225-4245; AM 1322-424; PRC C-45; Centaurus A

Finder Chart

The galaxy NGC 5128 is located in the constellation Centaurus, roughly 4.5° north of the giant globular cluster Omega Centauri which is visible to the naked eye. At a declination of -43° the is not visible from Europe. On 12 April it in opposition with the Sun and is therefore highest in the sky at around midnight.

Finder Chart Centaurus A (NGC 5128)
Centaurus A (NGC 5128) in constellation Centaurus. Charts created using SkySafari 6 Pro and STScI Digitized Sky Survey. Limiting magnitudes: Constellation chart ~6.5 mag, DSS2 close-ups ~20 mag. [149, 160]

Visual Observation

Binoculars: The galaxy is surprisingly well visible as a round, diffuse spot with a dark stripe across it, when sweeping north from Omega Centauri. — Astrofarm Tivoli, Namibia, September 2023, Bernd Nies

635 mm Aperture: At first glance I checked whether someone had smuggled a slide into the eyepiece of the telescope. The galaxy NGC 5128 looks exactly how one remembers it from the many pictures seen in books! A diffuse, elliptical galaxy inmidst thousands of brilliant stars. The warped band of dust shows many fine details. It is a very phantastic sight, allowing higher and higher magnifications. — 25" f/4 Obession Dobsonian, Astrofarm Tivoli, Namibia, September 2023, Bernd Nies

Objects Within a Radius of 20°

References

  • [11] «Results of astronomical observations made during the years 1834, 5, 6, 7, 8, at the Cape of Good Hope ... : being the completion of a telescopic survey of the whole surface of the visible heavens, commenced in 1825» Herschel, John F. W.; London : published by Smith, Elder and Co., 1847; DOI:10.3931/e-rara-22242
  • [29] Astrobin: AstroEdy's Gallery; astrobin.com/users/AstroEdy/collections
  • [45] Astro-, Landschafts- und Reisefotografie sowie Teleskopbau, Manuel Jung; sternklar.ch
  • [46] Astrofotografie mit Hansjörg Wälchli; upsky.ch
  • [50] «VIII. A catalogue of nebulæ and clusters of stars in the southern hemisphere, observed at Paramatta in New South Wales, by James Dunlop, Esq. In a letter addressed to Sir Thomas Makdougall Brisbane, Bart. K. C. B. late Governor of New South Wales. Presented to the Royal Society by John Frederick William Herschel, Esq. Vice President» James Dunlop;Philosophical Transactions of the Royal Society of London, Volume 118, pages 113-151, published 1 January 1828; DOI:10.1098/rstl.1828.0010
  • [149] SkySafari 6 Pro, Simulation Curriculum; skysafariastronomy.com
  • [160] The STScI Digitized Sky Survey; archive.stsci.edu/cgi-bin/dss_form
  • [199] «Atlas Of Peculiar Galaxies», Halton Arp, 1966; Astrophysical Journal Supplement, vol. 14, p.1 (1966); DOI:10.1086/190147; Bibcode:1966ApJS...14....1A; ned.ipac.caltech.edu/level5/Arp/frames.html
  • [277] «Historische Deep-Sky Kataloge» von Dr. Wolfgang Steinicke; klima-luft.de/steinicke (2021-02-17)
  • [659] Black hole outflows from Centaurus A detected with APEX; eso.org/public/news/eso0903 (2024-04-29)