NGC 2976
Galaxy in the constellation Ursa Major
title: "NGC 2976" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["dwarf-galaxies", "peculiar-galaxies", "unbarred-spiral-galaxies", "m81-group", "ursa-major", "ngc-objects", "ugc-objects", "principal-galaxies-catalogue-objects", "astronomical-objects-discovered-in-1801"] description: "Galaxy in the constellation Ursa Major" topic_path: "science/astronomy" source: "https://en.wikipedia.org/wiki/NGC_2976" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0
::summary Galaxy in the constellation Ursa Major ::
::data[format=table title="Infobox Galaxy"]
| Field | Value |
|---|---|
| name | NGC 2976 |
| image | File:NGC2976-hst-R814G606B475.jpg |
| image_size | 250px |
| epoch | J2000 |
| constellation name | Ursa Major |
| ra | |
| dec | |
| appmag_v | 10.8 |
| absmag_b | 16.90 |
| size_v | 5.89 × 3.02 |
| dist_ly | 3.56 ± |
| group_cluster | M81 Group |
| type | SAa |
| size | |
| notes | Peculiar |
| names | IRAS 09431+6809, UGC 5221, H I.285, PGC 28120 |
| :: |
| name = NGC 2976 | image = File:NGC2976-hst-R814G606B475.jpg | image_size = 250px | caption = | epoch = J2000 | constellation name = Ursa Major | ra = | dec = | appmag_v = 10.8 | appmag_b = | absmag_v = | absmag_b = 16.90 | size_v = 5.89 × 3.02 | dist_ly = 3.56 ± | z = | h_radial_v = | group_cluster = M81 Group | type = SAa | size = | mass = | notes = Peculiar | names = IRAS 09431+6809, UGC 5221, H I.285, PGC 28120
NGC 2976 is a peculiar dwarf galaxy in the northern constellation of Ursa Major. It was discovered by German-born astronomer William Herschel on November 8, 1801, and catalogued as H I.285. J. L. E. Dreyer described it as, "bright, very large, much extended 152°, star involved". It is a member of the M81 Group and lies 1° 20 to the southwest of Messier 81. The projected separation of this galaxy from the M81 Group is .
The morphological classification of this galaxy is SAa, which matches an unbarred spiral galaxy (SA) with very tightly-wound spiral arms (a). The actual visual form of the galaxy is a pure disk with no spiral arms or bulge. The luminosity and size of this galaxy is mid-way between the Large and Small Magellanic Clouds. De Vaucouleurs and associates classed it as type SAc, suggesting more loosely wound arms. It is inclined at an angle of 65° to the line of sight from the Earth.
Although appearing as a disk, there is evidence for a non-axisymmetric form of gas distribution, with a suggestion of central bar plus large-scale spiral arms. The inner structure contains many dark lanes and stellar condensations in its disk. There are two strong H II regions, one to each side. The overall star formation rate is y−1. The outer disk shows a history of steady star formation, although the formation rate has declined significantly over the last billion years and the population is now dominated by older stars. Within a radius of the center, star formation has been steady, having not undergone a recent decline.
There is a cloud of neutral hydrogen with a mass of located to the northeast of this galaxy, which may be interacting gravitationally with NGC 2976. The galaxy also shows evidence of tidal stripping, with an extended tidal tail of neutral hydrogen. The last significant interaction took place around one billion years ago.
::figure[src="https://upload.wikimedia.org/wikipedia/commons/5/5a/NGC_2976_Hubble_WikiSky.jpg" caption="Closeup of NGC 2976 by the [[Hubble Space Telescope"] ::
References
| title=NGC 2976 | access-date=2020-09-15 }}
| first=Courtney | last=Seligman | title=NGC Objects: NGC 2950 - 2999 | work=Celestial Atlas | url=https://cseligman.com/text/atlas/ngc29a.htm#2976 | accessdate=2016-03-01 }}
| title=The Advanced Camera for Surveys Nearby Galaxy Survey Treasury. IV. The Star Formation History of NGC 2976 | display-authors=1 | last1=Williams | first1=Benjamin F. | last2=Dalcanton | first2=Julianne J. | last3=Stilp | first3=Adrienne | last4=Gilbert | first4=Karoline M. | last5=Roškar | first5=Rok | last6=Seth | first6=Anil C. | last7=Weisz | first7=Daniel | last8=Dolphin | first8=Andrew | last9=Gogarten | first9=Stephanie M. | last10=Skillman | first10=Evan | last11=Holtzman | first11=Jon | journal=The Astrophysical Journal | volume=709 | issue=1 | pages=135–148 | date=January 2010 | arxiv=0911.4121 | bibcode=2010ApJ...709..135W | doi=10.1088/0004-637X/709/1/135 | s2cid=56054888 }}
| title=Non-axisymmetric Structure in the Satellite Dwarf Galaxy NGC 2976: Implications for its Dark/Bright Mass Distribution and Evolution | display-authors=1 | last1=Valenzuela | first1=Octavio | last2=Hernandez-Toledo | first2=Hector | last3=Cano | first3=Mariana | last4=Puerari | first4=Ivanio | last5=Buta | first5=Ronald | last6=Pichardo | first6=Bárbara | last7=Groess | first7=Robert | journal=The Astronomical Journal | volume=147 | issue=2 | id=27 | pages=8 | date=February 2014 | arxiv=1310.7021 | bibcode=2014AJ....147...27V | doi=10.1088/0004-6256/147/2/27 | s2cid=119246641 }}
| title=Seeking large-scale magnetic fields in a pure-disk dwarf galaxy NGC 2976 | display-authors=1 | last1=Drzazga | first1=R. T. | last2=Chyży | first2=K. T. | last3=Heald | first3=G. H. | last4=Elstner | first4=D. | last5=Gallagher | first5=J. S. | journal=Astronomy & Astrophysics | volume=589 | id=A12 | pages=16 | date=May 2016 | arxiv=1603.00482 | bibcode=2016A&A...589A..12D | doi=10.1051/0004-6361/201527236 | s2cid=119193441 }}
| title=Comparison LEDA/SIMBAD octobre 2002. Catalogue to be published in 2003 | last1=Paturel | first1=G. | last2=Dubois | first2=P. | last3=Petit | first3=C. | last4=Woelfel | first4=F. | display-authors=1 | journal=LEDA | date=2002 | bibcode=2002LEDA.........0P }}
| last1=Paturel | first1=G. | last2=Petit | first2=C. | last3=Prugniel | first3=Ph. | last4=Theureau | first4=G. | last5=Rousseau | first5=J. | last6=Brouty | first6=M. | last7=Dubois | first7=P. | last8=Cambrésy | first8=L. | title=HYPERLEDA. I. Identification and designation of galaxies | display-authors=1 | journal=Astronomy and Astrophysics | volume=412 | pages=45–55 | date=December 2003 | doi=10.1051/0004-6361:20031411 | doi-access=free | bibcode=2003A&A...412...45P }}
| title=NGC 2976 | date=March 29, 1998 | first1=Hartmut | last1=Frommert | first2=Christine | last2=Kronberg | website=Students for the Exploration and Development of Space | url=http://messier.seds.org/xtra/ngc/n2976.html | accessdate=2020-09-14 }}
| title=NASA/IPAC Extragalactic Database | work=Results for NGC 2976 | url=http://nedwww.ipac.caltech.edu/ | accessdate=2006-11-25 }}
| title=A Catalog of Neighboring Galaxies | first1=I. D. | last1=Karachentsev | first2=V. E. | last2=Karachentseva | first3=W. K. | last3=Hutchmeier | first4=D. I. | last4=Makarov | display-authors=1 | journal=Astronomical Journal | date=2004 | volume=127 | issue=4 | pages=2031–2068 | bibcode=2004AJ....127.2031K | doi=10.1086/382905 | doi-access=free }}
| last1=Karachentsev | first1=I. D. | last2=Kashibadze | first2=O. G. | title=Masses of the local group and of the M81 group estimated from distortions in the local velocity field | journal=Astrophysics | date=2006 | volume=49 | issue=1 | pages=3–18 | bibcode=2006Ap.....49....3K | doi=10.1007/s10511-006-0002-6 | s2cid=120973010 }}
References
- (1 February 2006). "The Two Micron All Sky Survey (2MASS)". The Astronomical Journal.
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