NGC 4945
Galaxy in the constellation Centaurus
title: "NGC 4945" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["barred-spiral-galaxies", "centaurus-a/m83-group", "centaurus", "ngc-objects", "principal-galaxies-catalogue-objects", "caldwell-objects", "astronomical-objects-discovered-in-1826", "seyfert-galaxies", "iras-catalogue-objects", "eso-objects"] description: "Galaxy in the constellation Centaurus" topic_path: "science/astronomy" source: "https://en.wikipedia.org/wiki/NGC_4945" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0
::summary Galaxy in the constellation Centaurus ::
::data[format=table title="Infobox galaxy"]
| Field | Value |
|---|---|
| name | NGC 4945 |
| image | Spiral Galaxy NGC 4945.jpg |
| image_scale | 1.5 |
| caption | NGC 4945 image take by the MPG/ESO 2.2-metre telescope at La Silla Observatory |
| alt | |
| epoch | J2000 |
| constellation name | Centaurus |
| ra | |
| dec | |
| z | 0.001868 |
| h_radial_v | |
| gal_v | |
| dist_ly | 3.36 ± |
| group_cluster | Centaurus A/M83 Group |
| type | SB(s)cd?edge |
| mass | |
| mass_light_ratio | |
| stars | |
| size | 165,185 ly (50.67 kpc) (estimated) |
| appmag_v | 9.3 |
| appmag_b | |
| absmag_v | |
| mag_j | |
| mag_h | |
| mag_k | |
| sbrightness | |
| size_v | |
| half_light_radius_pc | |
| half_light_radius_arcminsec | |
| h1_scale_length_pc | |
| h1_scale_length_arcminsec | |
| xray_radius_pc | |
| xray_radius_arcminsec | |
| notes | Seyfert 2 galaxy |
| names | |
| references | |
| :: |
| name = NGC 4945 | image = Spiral Galaxy NGC 4945.jpg | image_scale = 1.5 | caption = NGC 4945 image take by the MPG/ESO 2.2-metre telescope at La Silla Observatory | alt = | epoch = J2000 | pronounce = | constellation name = Centaurus | ra = | dec = | z = 0.001868 | h_radial_v = | gal_v = | dist_ly = 3.36 ± | group_cluster = Centaurus A/M83 Group | type = SB(s)cd?edge | mass = | mass_light_ratio = | stars = |size = 165,185 ly (50.67 kpc) (estimated) | appmag_v = 9.3 | appmag_b = | absmag_v = | mag_j = | mag_h = | mag_k = | sbrightness = | size_v = | half_light_radius_pc = | half_light_radius_arcminsec = | h1_scale_length_pc = | h1_scale_length_arcminsec = | xray_radius_pc = | xray_radius_arcminsec = | notes = Seyfert 2 galaxy | names = | references =
NGC 4945 is a widely-studied barred spiral galaxy in the constellation Centaurus, visible near the optical double star Xi Centauri. It is also known as Caldwell 83. The galaxy was discovered by Scottish astronomer James Dunlop in 1826. It is located at a distance of approximately 3.36 Mpc from the Milky Way. NGC 4945 hosts one of the closest active galactic nuclei to Earth and is classified as a Seyfert 2 galaxy.
NGC 4945 is one of the brightest galaxies of the Centaurus A/M83 Group, a large, nearby group of galaxies. The galaxy is the second brightest galaxy in the subgroup centered on Centaurus A.
Observations
The morphological classification of NGC 4945 is SB(s)cd?edge, indicating this is a barred spiral galaxy (SB) with no inner ring structure (s) and possibly loosely-wound spiral arms (cd?). It is inclined at an angle of 90° to the plane of the sky, which means the galactic plane is being viewed edge-on. NGC 4945 is thought to be similar to the Milky Way Galaxy, although the maximum rotation rate of is lower. It has a combined estimated mass of . The stellar mass of the galaxy is , or 38 billion times the mass of the Sun.
In 1964, this galaxy was classified as a radio source at the Parkes Observatory. The nucleus was obscured in the optical band but was found to be a quite prominent source of infrared emission. It is the third brightest galaxy in the IRAS point source catalogue, with most of the emission coming from the core. Most of the Galaxy shows a linear rotation curve, although the southwest region showed an infall suggestive of a bar.
::figure[src="https://upload.wikimedia.org/wikipedia/commons/6/6f/Supermassive_black_hole_caught_playing_with_its_food_(potw2513a).jpg" caption="X-ray]] emission from the nuclear region indicates a Type 2 Seyfert galaxy. It is a strong emitter of hard X-rays, second only to [[NGC 4151]], and likely harbors a [[supermassive black hole]]."] ::
The starburst region is thought to be at least years old and contributes at least half of the luminosity coming from the core. It is concentrated in the central 100 pc and includes a conical cavity likely produced by supernovae-driven winds. This is taking place in a region of dense molecular clouds, forming a disk of dust and gas, along with many rich star clusters. A hot wind of gas from the nuclear region is carrying away per year.
NGC 4945 was the first galaxy outside the Local Group to have stars resolved within its galactic halo. The halo mass is relatively large at and it is metal-rich, both of which are typical for a Milky Way-like galaxy. It appears to be counter-rotating compared to the main disk, suggesting the halo has been accreted. The mass of the dominant satellite accreted into the halo is , which is roughly the same as the Large Magellanic Cloud.
In October 2023, researchers using ALMA discovered an unknown object around 200 light years from the center of the galaxy. This object, named Punctum (Latin for "point" or "dot"), is a highly-polarized millimeter continuum source of synchrotron radiation. Punctum has a high non-visible luminosity, with archive data from Chandra reporting a X-ray luminosity in the 3–6 keV range and ATCA data reporting a radio luminosity of at 23 GHz. In a paper published in July 2025 about the object, the researchers said it most resembles a magnetar due to its polarization of , however the millimeter luminosity of said objects is usually much lower.
Supernovae
Two supernovae have been observed in NGC 4945:
- SN 2005af (TypeII-P, mag. 12.8) was discovered by CEAMIG/REA Supernovae Search on 8 February 2005, reaching a peak magnitude of 12.5 on 12 February.
- SN 2011ja (Type II-P, mag. 14) was discovered by Libert "Berto" Monard on 18 December 2011, and achieved a maximum magnitude of 11.7 on 9 January 2012. The progenitor star for 2011ja may have been massive at and located within a massive stellar cluster.
In popular culture
"NGC 4945" is the title of a song by Brett Domino on the album Funk.
Image gallery
File:NGC4945Location.png|The location of NGC 4945 (labelled in red)
References
| url = https://www.rochesterastronomy.org/sn2011/sn2011ja.html | title = Supernova 2011ja in NGC 4945 | last = Bishop | first = David | website = Rochester Astronomy | access-date = 14 July 2025}}
| title=NGC 4945 | access-date=2025-03-08 | postscript=. | mode = cs2 }}
| title=NASA/IPAC Extragalactic Database | work=Results for NGC 4945 | url=http://nedwww.ipac.caltech.edu/ | access-date=2006-11-25 }}
| title=NGC 4945 | work=DOCdb :Deep Sky Observer's Companion – the online database | url=http://www.docdb.net/show_object.php?id=ngc_4945 | access-date=2025-03-08 }}
| title=Milky Way's Not-So-Distant Cousin Likely Harbors Supermassive Black Hole | publisher=Science Daily | url=https://www.sciencedaily.com/releases/2009/09/090902112111.htm | access-date=2025-03-08 }}
| title=Populating the Galaxy Velocity Dispersion – Supermassive Black Hole Mass Diagram: A Catalogue of (Mbh, σ) Values | last=Graham | first=Alister W. | journal=Publications of the Astronomical Society of Australia | volume=25 | issue=4 | pages=167–175 | date=November 2008 | doi=10.1071/AS08013 | arxiv=0807.2549 | bibcode=2008PASA...25..167G | s2cid=89905 }}
| title=An Infrared View of the Obscured AGN Environment in NGC 4945 | display-authors=1 | last1=Gaspar | first1=G. | last2=Díaz | first2=R. J. | last3=Mast | first3=D. | last4=Agüero | first4=M. P. | last5=Schirmer | first5=M. | last6=Günthardt | first6=G. | last7=Schmidt | first7=E. O. | journal=The Astronomical Journal | volume=163 | issue=5 | page=230 | year=2022 | arxiv=2203.03678 | bibcode=2022AJ....163..230G | s2cid=247315251 | doi=10.3847/1538-3881/ac5ea4 | doi-access=free }}
| title=New distances to galaxies in the Centaurus A group | first1=I. D. | last1=Karachentsev | first2=M. E. | last2=Sharina | first3=A. E. | last3=Dolphin | first4=E. K. | last4=Grebel | first5=D. | last5=Geisler | first6=P. | last6=Guhathakurta | first7=P. W. | last7=Hodge | first8=V. E. | last8=Karachentseva | first9=A. | last9=Sarajedini | first10=P. | last10=Seitzer | display-authors=4 | journal=Astronomy and Astrophysics | date=2002 | volume=385 | issue=1 | pages=21–31 | bibcode=2002A&A...385...21K | doi=10.1051/0004-6361:20020042| doi-access=free }}
| title=The Local Group and Other Neighboring Galaxy Groups | first=I. D. | last=Karachentsev | journal=Astronomical Journal | date=2005 | volume=129 | issue=1 | pages=178–188 | bibcode=2005AJ....129..178K | s2cid=119385141 | doi=10.1086/426368 | arxiv=astro-ph/0410065 }}
| title=Possible Supernova in NGC 4945 | last1=Jacques | first1=C. | last2=Pimentel | first2=E. | journal=International Astronomical Union Circular | date=2005 | issue=8482 | page=1 | bibcode=2005IAUC.8482....1J }}
| title=SN 2005af | publisher = IAU | website=Transient Name Server | url=https://www.wis-tns.org/object/2005af | access-date=8 December 2024 }}
| title=Supernova 2011ja in NGC 4945 = PSN J13051112-4931270 | last1=Monard | first1=L. A. G. | last2=Milisavljevic | first2=D. | last3=Fesen | first3=R. | last4=Pickering | first4=T. | last5=Romero-Colmenero | first5=E. | last6=Turatto | first6=M. | last7=Benetti | first7=S. | last8=Pastorello | first8=A. | last9=Valenti | first9=S. | last10=Bufano | first10=F. | last11=Tomasella | first11=L. | last12=Ryder | first12=S. | last13=Soderberg | first13=A. | last14=Stockdale | first14=C. | last15=Van Dyk | first15=S. | last16=Immler | first16=S. | last17=Weiler | first17=K. | last18=Panagia | first18=N. | display-authors=1 | journal=Central Bureau Electronic Telegrams | date=2011| issue=2946| page=1 | bibcode=2011CBET.2946....1M }}
| website=Transient Name Server | title=SN2011ja | publisher = IAU | url=https://www.wis-tns.org/object/2011ja | access-date=8 December 2024 }}
| title=The Two Micron All Sky Survey (2MASS) | last1=Skrutskie | first1=Michael F. | last2=Cutri | first2=Roc M. | last3=Stiening | first3=Rae | last4=Weinberg | first4=Martin D. | last5=Schneider | first5=Stephen E. | last6=Carpenter | first6=John M. | last7=Beichman | first7=Charles A. | last8=Capps | first8=Richard W. | last9=Chester | first9=Thomas | last10=Elias | first10=Jonathan H. | last11=Huchra | first11=John P. | last12=Liebert | first12=James W. | last13=Lonsdale | first13=Carol J. | last14=Monet | first14=David G. | last15=Price | first15=Stephan | last16=Seitzer | first16=Patrick | last17=Jarrett | first17=Thomas H. | last18=Kirkpatrick | first18=J. Davy | last19=Gizis | first19=John E. | last20=Howard | first20=Elizabeth V. | last21=Evans | first21=Tracey E. | last22=Fowler | first22=John W. | last23=Fullmer | first23=Linda | last24=Hurt | first24=Robert L. | last25=Light | first25=Robert M. | last26=Kopan | first26=Eugene L. | last27=Marsh | first27=Kenneth A. | last28=McCallon | first28=Howard L. | last29=Tam | first29=Robert | last30=Van Dyk | first30=Schuyler D. | last31=Wheelock | first31=Sherry L. | display-authors=1 | journal=The Astronomical Journal | date=February 1, 2006 | volume=131 | issue=2 | pages=1163–1183 | bibcode=2006AJ....131.1163S | s2cid=18913331 | doi=10.1086/498708 | doi-access=free | issn=0004-6256 }}
| title=On the association between core-collapse supernovae and H II regions | last=Crowther | first=Paul A. | journal=Monthly Notices of the Royal Astronomical Society | volume=428 | issue=3 | pages=1927–1943 | date=January 2013 | doi=10.1093/mnras/sts145 | doi-access=free | arxiv=1210.1126 | bibcode=2013MNRAS.428.1927C }}
| title=Third Reference Catalogue of Bright Galaxies | last1=de Vaucouleurs | first1=G. | last2=de Vaucouleurs | first2=A. | last3=Corwin | first3=H. G. Jr. | last4=Buta | first4=R. J. | last5=Paturel | first5=G. | last6=Fouqué | first6=P. | display-authors=1 | year=2016 | version=9 | location=New York | publisher=Springer-Verlag | url=https://heasarc.gsfc.nasa.gov/W3Browse/all/rc3.html | access-date=2025-03-08 }}
| title=Caldwell 83 | website=science.nasa.gov | date=10 September 2020 | publisher=NASA | url=https://science.nasa.gov/mission/hubble/science/explore-the-night-sky/hubble-caldwell-catalog/caldwell-83/ | access-date=2025-03-12 }}
| title=First resolved stellar halo kinematics of a Milky Way-mass galaxy outside the Local Group: The flat counter-rotating halo in NGC 4945 | last1=Beltrand | first1=Camila | last2=Monachesi | first2=Antonela | last3=D'Souza | first3=Richard | last4=Bell | first4=Eric F. | last5=de Jong | first5=Roelof S. | last6=Gomez | first6=Facundo A. | last7=Bailin | first7=Jeremy | last8=Jang | first8=In Sung | last9=Smercina | first9=Adam | display-authors=1 | journal=Astronomy & Astrophysics | volume=690 | at=id. A115 | date=October 2024 | doi=10.1051/0004-6361/202450626 | arxiv=2406.17533 | bibcode=2024A&A...690A.115B }}
| title=Optical polarimetric monitoring of the type II-plateau SN 2005af | display-authors=1 | last1=Pereyra | first1=A. | last2=Magalhães | first2=A. M. | last3=Rodrigues | first3=C. V. | last4=Silva | first4=C. R. | last5=Campos | first5=R. | last6=Hickel | first6=G. | last7=Cieslinski | first7=D. | journal=Astronomy and Astrophysics | volume=454 | issue=3 | date=August 2006 | pages=827–831 | doi=10.1051/0004-6361:20065207 | arxiv=astro-ph/0604511 | bibcode=2006A&A...454..827P }}
| title=Early dust formation and a massive progenitor for SN 2011ja? | display-authors=1 | last1=Andrews | first1=J. E. | last2=Krafton | first2=Kelsie M. | last3=Clayton | first3=Geoffrey C. | last4=Montiel | first4=E. | last5=Wesson | first5=R. | last6=Sugerman | first6=Ben E. K. | last7=Barlow | first7=M. J. | last8=Matsuura | first8=M. | last9=Drass | first9=H. | journal=Monthly Notices of the Royal Astronomical Society | volume=457 | issue=3 | pages=3241–3253 | date=April 2016 | doi=10.1093/mnras/stw164 | doi-access=free | arxiv=1509.06379 | bibcode=2016MNRAS.457.3241A }}
| title=An Infrared View of the Obscured AGN Environment in NGC 4945 | display-authors=1 | last1=Gaspar | first1=G. | last2=Díaz | first2=R. J. | last3=Mast | first3=D. | last4=Agüero | first4=M. P. | last5=Schirmer | first5=M. | last6=Günthardt | first6=G. | last7=Schmidt | first7=E. O. | journal=The Astronomical Journal | volume=163 | issue=5 | at=id. 230 | date=May 2022 | doi=10.3847/1538-3881/ac5ea4 | doi-access=free | arxiv=2203.03678 | bibcode=2022AJ....163..230G }}
| title=The nucleus of the southern spiral NGC 4945 | last1=Shobbrook | first1=R. R. | last2=Shaver | first2=P. A. | journal=The Observatory | volume=87 | pages=169–170 | date=August 1967 | bibcode=1967Obs....87..169S }}
| title=The Parkes catalogue of radio sources, declination zone −20° to −60° | display-authors=1 | last1=Bolton | first1=J. G. | last2=Gardner | first2=F. F. | last3=Mackey | first3=M. B. | journal=Australian Journal of Physics | volume=17 | page=340 | date=September 1964 | issue=3 | doi=10.1071/PH640340 | bibcode=1964AuJPh..17..340B }}
| title=Observations of the kinematics of the excited gas in the late-type spiral galaxy NGC 4945 | last=Peterson | first=C. J. | journal=Publications of the Astronomical Society of the Pacific | volume=92 | pages=397–408 | date=August 1980 | doi=10.1086/130685 | bibcode=1980PASP...92..397P }}
| title=Infrared activity in Circinus and NGC 4945 : two galaxies containing luminous H2 O masers. | last1=Moorwood | first1=A. F. M. | last2=Glass | first2=I. S. | journal=Astronomy and Astrophysics | volume=135 | pages=281–288 | date=June 1984 | bibcode=1984A&A...135..281M }}
| title=NGC 4945 – a galaxy with a nucleus full of surprises | last=Whiteoak | first=J. B. | journal=Astronomical Society of Australia, Proceedings | volume=6 | issue=4 | year=1986 | pages=467–471 | doi=10.1017/S1323358000018403 | bibcode=1986PASA....6..467W }}
| title=NGC 4945: The brightest Seyfert 2 galaxy at 100 keV | display-authors=1 | last1=Done | first1=C. | last2=Madejski | first2=G. M. | last3=Smith | first3=D. A. | journal=Astrophysical Journal Letters | volume=463 | page=L63 | date=June 1996 | issue=2 | doi=10.1086/310056 | bibcode=1996ApJ...463L..63D }}
| title=Mid-infrared ISO spectroscopy of NGC 4945 | display-authors=1 | last1=Spoon | first1=H. W. W. | last2=Koornneef | first2=J. | last3=Moorwood | first3=A. F. M. | last4=Lutz | first4=D. | last5=Tielens | first5=A. G. G. M. | journal=Astronomy and Astrophysics | volume=357 | pages=898–908 | date=May 2000 | arxiv=astro-ph/0003457 | bibcode=2000A&A...357..898S }}
| title=Dense gas in nearby galaxies. XVI. The nuclear starburst environment in NGC 4945 | display-authors=1 | last1=Wang | first1=M. | last2=Henkel | first2=C. | last3=Chin | first3=Y. -N. | last4=Whiteoak | first4=J. B. | last5=Hunt Cunningham | first5=M. | last6=Mauersberger | first6=R. | last7=Muders | first7=D. | journal=Astronomy and Astrophysics | volume=422 | pages=883–905 | date=August 2004 | issue=3 | doi=10.1051/0004-6361:20035722 | arxiv=astro-ph/0405346 | bibcode=2004A&A...422..883W }}
| title=The nuclear molecular clouds of NGC4945 | last1=Cunningham | first1=M. R. | last2=Whiteoak | first2=J. B. | journal=Monthly Notices of the Royal Astronomical Society | volume=364 | issue=1 | pages=37–46 | date=November 2005 | doi=10.1111/j.1365-2966.2005.09502.x | doi-access=free | bibcode=2005MNRAS.364...37C }}
| title=Super star clusters in the central starburst of NGC 4945 | last1=Emig | first1=Kimberly L. | last2=Bolatto | first2=Alberto D. | last3=Leroy | first3=Adam K. | last4=Mills | first4=Elisabeth A. C. | last5=Jiménez Donaire | first5=María J. | last6=Tielens | first6=Alexander G. G. M. | last7=Ginsburg | first7=Adam | last8=Gorski | first8=Mark | last9=Krieger | first9=Nico | last10=Levy | first10=Rebecca C. | last11=Meier | first11=David S. | last12=Ott | first12=Jürgen | last13=Rosolowsky | first13=Erik | last14=Thompson | first14=Todd A. | last15=Veilleux | first15=Sylvain | display-authors=1 | journal=The Astrophysical Journal | volume=903 | issue=1 | at=id. 50 | date=November 2020 | doi=10.3847/1538-4357/abb67d | doi-access=free | arxiv=2009.05154 | bibcode=2020ApJ...903...50E }}
| title=Hot Gas Outflow Properties of the Starburst Galaxy NGC 4945 | last1=Porraz Barrera | first1=Natalia | last2=Lopez | first2=Sebastian | last3=Lopez | first3=Laura A. | last4=Foord | first4=Adi | last5=Nguyen | first5=Dustin D. | last6=Thompson | first6=Todd A. | last7=Mathur | first7=Smita | last8=Bolatto | first8=Alberto D. | display-authors=1 | journal=The Astrophysical Journal | volume=968 | issue=2 | at=id. 54 | date=June 2024 | doi=10.3847/1538-4357/ad4606 | doi-access=free | arxiv=2312.08444 | bibcode=2024ApJ...968...54P }}
References
- (2025). "ALMA discovery of Punctum – a highly polarized mm source in nuclear starburst galaxy NGC 4945".
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