NGC 1232

Last updated
NGC 1232
NGC 1232.jpg
NGC 1232 by ESO
Observation data (J2000 epoch)
Constellation Eridanus
Right ascension 03h 09m 45.5s [1]
Declination −20° 34′ 46″ [1]
Redshift 0.005347 [1]
Heliocentric radial velocity 1603 ± 1 km/s [1]
Distance 61 ± 8.5 Mly
(18.7 ± 2.6 Mpc) [2]
Apparent magnitude  (V)10.9 [1]
Characteristics
Type SAB(rs)c [1]
Apparent size  (V)7′.4 × 6′.5 [1]
Notable featuresDiscrepant galaxy pair with NGC 1232 A
Other designations
PGC 11819, [1] Arp 41 [1]

NGC 1232, also known as the Eye of God Galaxy (not to be confused with the Helix Nebula, also known as Eye of God) is an intermediate spiral galaxy about 60 million light-years away [2] in the constellation Eridanus. It was discovered by German-British astronomer William Herschel on 20 October 1784. [3]

Contents

It is dominated by millions of bright stars and dark dust, in spiral arms rotating about the center. Open clusters containing bright blue stars are sprinkled along these spiral arms, with dark lanes of dense interstellar dust between. Less visible are dimmer stars and interstellar gas, comprising such a high mass that they dominate the dynamics of the inner galaxy. Not visible is matter of unknown form called dark matter, needed to explain the motions of the visible material in the outer galaxy. The galaxy is approximately 200,000 light-years across. The galaxy's spiral arms are not smooth and perturbed, leading to some suggesting a collision with a dwarf galaxy. [4] [5] However, some studies doubt this suggestion. [6]

NGC 1232 and its apparent companions are possibly part of the Eridanus cluster of galaxies, along with NGC 1300.

Description and structure

NGC 1232 is a face-on spiral galaxy. It can be technically considered a grand-design galaxy and is considered a prototype for multi-arm spiral galaxies. [7] Its galactic bulge is small. While NGC 1232 is classified as an intermediate spiral galaxy, the bulge shows hints of a galactic bar. [7]

Spiral arms

NGC 1232's spiral arms are bright and flocculent, winding counterclockwise from the galactic center. They contain numerous HII regions. [7] At large distances from the galaxy's center, the spiral arms either branch out and disperse, producing long spiral arms, or connect with arm segments. [8] However, they are not smooth as expected for a spiral galaxy. Instead, they bend abruptly and show significant deviations from a constant pitch. In fact, the same pitch angle cannot be applied to one arm due to the arms deviating. Astronomer Halton Arp suggested that this is the result of a galaxy interaction. That the galaxy contains numerous star-forming regions makes it an excellent laboratory when it comes to studies on star formation. [4]

Most of NGC 1232's arms and arm segments widen as they get farther and farther away from the galaxy's center with only one arm or arm segment, designated as arm segment "E", narrowing as it gets further from the center. This is likely due to less and less star formation occurring at farther distances from the galaxy's center, or it may be because the spiral arm reaches a point where the spiral pattern starts to co-rotate orbiting material. [8]

An image of NGC 1232. The arm segment designated as "E" is at the right-most bright spiral arm of the galaxy. Note the number of arms. Spiral Galaxy NGC 1232 (wallpaper).jpg
An image of NGC 1232. The arm segment designated as "E" is at the right-most bright spiral arm of the galaxy. Note the number of arms.

Association with the Eridanus cluster

NGC 1232 and NGC 1232 A may both be associated with the Eridanus cluster of galaxies, but with a distance of around 2.2 million parsecs from the cluster's center, they may not be bound to the cluster. [7]

Debated collision with another dwarf galaxy and association with NGC 1232A

It was originally thought that one of NGC 1232's companions, NGC 1232A, was interacting with NGC 1232 and causing perturbations within its disk, as NGC 1232A seems to be a satellite galaxy of NGC 1232 at first sight, [9] but this is likely not the case. In 1988, NGC 1232A was estimated to be 68 million light-years away [10] while NGC 1232 was estimated to be 65 million light-years away. [2] The redshifts of the two galaxies do not match, which suggest that they likely never interacted before and are not currently interacting. The discrepant redshifts for the two galaxies is one of the reasons why the pair is known as one of the most striking examples for discrepant redshifts in galaxy pairs. [6] Instead, X-Ray studies suggest that NGC 1232 may have interacted with a dwarf galaxy, but the dwarf galaxy has apparently left no remnant. [4]

X-Ray observations over a three-year period made by the Chandra X-ray observatory also suggest that there was an interaction between NGC 1232 and another dwarf galaxy, commenting on a massive cloud of gas only visible in the X-ray superimposed on NGC 1232's images. The paper concludes that this may be the first case of the dwarf galaxy-large galaxy collision whose evidence is only visible in the X-Ray. However, it is noted that this may be due to other causes, such as numerous supernovae, but the study also suggests that there is no other evidence for this. [5] As a result, an interaction with another galaxy, other than NGC 1232A, is sometimes thought to be the cause of unusual bending in the spiral arms. In 2018, a study of the star formation rates in NGC 1232 took images of the galaxy in Hydrogen Alpha, finding over 970 HII regions. It is remarked that there is a concentration of HII regions in one part of the galaxy, but when the star-formation rates are taken into account, the concentration is more diluted. The study found that X-Ray emissions may be quenching star formation in some areas of the galaxy, because there seems to be lower concentration of HII regions there. The amount of HII regions seems to be higher in areas without much X-ray emission. Both of these were suggested to have been caused by a collision with another galaxy. [4]

In contrast with previous studies, a recent X-Ray study remarks that the hot gas luminosity in NGC 1232 is not very high. According to the study, the cloud claimed to be superimposed on NGC 1232 does not exist, and that peculiarities in NGC 1232's HII regions are just coincidental. The study notes that NGC 1232's disk is not very warped. Thus, the study concludes that there was no interaction between either NGC 1232A or another dwarf galaxy and NGC 1232 at all. [6]

See also

Related Research Articles

<span class="mw-page-title-main">Galaxy</span> Large gravitationally bound system of stars and interstellar matter

A galaxy is a system of stars, stellar remnants, interstellar gas, dust, and dark matter bound together by gravity. The word is derived from the Greek galaxias (γαλαξίας), literally 'milky', a reference to the Milky Way galaxy that contains the Solar System. Galaxies, averaging an estimated 100 million stars, range in size from dwarfs with less than a thousand stars, to the largest galaxies known – supergiants with one hundred trillion stars, each orbiting its galaxy's center of mass. Most of the mass in a typical galaxy is in the form of dark matter, with only a few percent of that mass visible in the form of stars and nebulae. Supermassive black holes are a common feature at the centres of galaxies.

<span class="mw-page-title-main">NGC 7742</span> Galaxy in the constellation Pegasus

NGC 7742 also known as Fried Egg Galaxy is a face-on unbarred spiral galaxy in the constellation Pegasus. Its velocity with respect to the cosmic microwave background is 1292 ± 26 km/s, which corresponds to a Hubble distance of 62.2 ± 4.5 Mly (19.06 ± 1.39 Mpc). In addition, six non-redshift measurements give a farther distance of 84.09 ± 26.51 Mly (25.783 ± 8.129 Mpc). It was discovered by German-British astronomer William Herschel on 18 Oct 1784.

<span class="mw-page-title-main">NGC 2683</span> Galaxy in the constellation Lynx

NGC 2683 is a field spiral galaxy in the northern constellation of Lynx. It was nicknamed the "UFO Galaxy" by the Astronaut Memorial Planetarium and Observatory. It was discovered by the astronomer William Herschel on February 5, 1788.

<span class="mw-page-title-main">NGC 3521</span> Galaxy in the constellation Leo

NGC 3521 is a flocculent intermediate spiral galaxy located in the constellation Leo. Its velocity with respect to the cosmic microwave background is 1167 ± 26 km/s, which corresponds to a Hubble distance of 56.1 ± 4.1 Mly (17.21 ± 1.26 Mpc). However, 26 non-redshift measurements give a much closer distance of 37.17 ± 1.83 Mly (11.395 ± 0.56 Mpc). It was discovered by German-British astronomer William Herschel on 22 February 1784.

<span class="mw-page-title-main">NGC 520</span> Pair of colliding spiral galaxies in the constellation Pisces

NGC 520, also known as the Flying Ghost, is a pair of colliding spiral galaxies about 105 million light-years away in the constellation Pisces. They were discovered by astronomer William Herschel on 13 December 1784.

<span class="mw-page-title-main">NGC 6872</span> Galaxy in the constellation Pavo

NGC 6872, also known as the Condor Galaxy, is a large barred spiral galaxy of type SB(s)b pec in the constellation Pavo. It is 212 million light-years (65 Mpc) from Earth. NGC 6872 is interacting with the lenticular galaxy IC 4970, which is less than one twelfth as large. The galaxy has two elongated arms with a diameter based on ultraviolet light of over 522,000 light-years (160,000 pc), and a D25.5 isophotal diameter of over 717,000 light-years (220,000 pc), making it the largest known spiral galaxy. It was discovered on 27 June 1835 by English astronomer John Herschel.

The Eridanus Group, sometimes called the Eridanus Cloud, is a nearby loose grouping of galaxies at a mean distance of approximately 75 Mly in the constellation Eridanus. Redshift values show that there are approximately 200 galaxies associated with the group, approximately 70% of which are spiral and irregular type galaxies while the remaining 30% are elliptical and lenticular types.

<span class="mw-page-title-main">NGC 922</span> Peculiar galaxy in the constellation Fornax

NGC 922 is a peculiar galaxy in the southern constellation of Fornax. Its velocity with respect to the cosmic microwave background is 2879 ± 15 km/s, which corresponds to a Hubble distance of 138.5 ± 9.7 Mly (42.46 ± 2.98 Mpc). Additionally, 17 non-redshift measurements give a distance of 138.88 ± 7.47 Mly (42.582 ± 2.291 Mpc). It was discovered by German-British astronomer William Herschel on 17 November 1784.

<span class="mw-page-title-main">NGC 4522</span> Spiral galaxy in the constellation of Virgo

NGC 4522 is an edge-on spiral galaxy located about 60 million light-years away within the Virgo Cluster in the constellation Virgo. NGC 4522 is losing its molecular gas though ram-pressure stripping as it plows though the cluster at a speed of more than 10 million kilometres per hour. The galaxy was discovered by astronomer John Herschel on January 18, 1828.

<span class="mw-page-title-main">NGC 3256</span> Peculiar galaxy in the constellation Vela

NGC 3256 is a peculiar galaxy formed from the collision of two separate galaxies in the constellation of Vela. NGC 3256 is located about 100 million light-years away and belongs to the Hydra–Centaurus Supercluster complex. NGC 3256 provides a nearby template for studying the properties of young star clusters in tidal tails. The system hides a double nucleus and a tangle of dust lanes in the central region. The telltale signs of the collision are two extended luminous tails swirling out from the galaxy. The tails are studded with a particularly high density of star clusters. NGC 3256 is the most luminous galaxy in the infrared spectrum located within z 0.01 from Earth.

<span class="mw-page-title-main">NGC 615</span> Galaxy in the constellation Cetus

NGC 615 is an unbarred spiral galaxy seen edge-on located in the constellation Cetus. It is located at a distance of circa 70 million light years from Earth, which, given its apparent dimensions, means that NGC 615 is about 75,000 light years across. It was discovered by William Herschel on January 10, 1785. NGC 615 belongs to the NGC 584 galaxy group, which also includes the galaxies NGC 584, NGC 596, NGC 600, and NGC 636.

<span class="mw-page-title-main">NGC 2336</span> Galaxy in the constellation Camelopardalis

NGC 2336 is a barred spiral galaxy located in the constellation Camelopardalis. It is located at a distance of circa 100 million light years from Earth, which, given its apparent dimensions, means that NGC 2336 is about 200,000 light years across. It was discovered by Wilhelm Tempel in 1876.

<span class="mw-page-title-main">NGC 2835</span> Spiral galaxy in the constellation Hydra

NGC 2835 is an intermediate spiral galaxy located in the constellation Hydra. It is located at a distance of circa 35 million light years from Earth, which, given its apparent dimensions, means that NGC 2835 is about 65,000 light years across. It was discovered by Wilhelm Tempel on April 13, 1884. NGC 2835 is located only 18.5 degrees from the galactic plane.

<span class="mw-page-title-main">NGC 541</span> Galaxy in the constellation Cetus

NGC 541 is a lenticular galaxy located in the constellation Cetus. It is located at a distance of about 230 million light years from Earth, which, given its apparent dimensions, means that NGC 541 is about 130,000 light years across. It was discovered by Heinrich d'Arrest on October 30, 1864. It is a member of the Abell 194 galaxy cluster and is included in the Atlas of Peculiar Galaxies in the category galaxies with nearby fragments. NGC 541 is a radio galaxy of Fanaroff–Riley class I, also known as 3C 40A.

<span class="mw-page-title-main">NGC 1386</span> Galaxy in the constellation Eridanus

NGC 1386 is a spiral galaxy located in the constellation Eridanus. It is located at a distance of circa 53 million light years from Earth, which, given its apparent dimensions, means that NGC 1386 is about 50,000 light years across. It is a Seyfert galaxy, the only one in Fornax Cluster.

<span class="mw-page-title-main">NGC 4848</span> Galaxy in the constellation Coma Berenices

NGC 4848 is a barred spiral galaxy in the constellation Coma Berenices. It is circa 340 million light-years from Earth, which, given its apparent dimensions, means that NGC 4848 is about 170,000 light years across. It was discovered by Heinrich d'Arrest on April 21, 1865. It is considered part of the Coma Cluster, which is in its northwest part. The galaxy has been stripped of its gas as it passed through the cluster.

<span class="mw-page-title-main">NGC 4393</span> Galaxy in the constellation of Coma Berenices

NGC 4393 is a spiral galaxy about 46 million light-years away in the constellation Coma Berenices. It was discovered by astronomer William Herschel on April 11, 1785. It is a member of the NGC 4274 Group, which is part of the Coma I Group or Cloud.

<span class="mw-page-title-main">NGC 2445</span> Galaxy in the constellation Lynx

NGC 2445 is a peculiar ring galaxy in the constellation Lynx. The galaxy lies about 200 million light years away from Earth, which means, given its apparent dimensions, that NGC 2445 is approximately 100,000 light years across. It was discovered by Édouard Stephan on January 18, 1877. The galaxy interacts with another galaxy, NGC 2444, and as a result its shape is distorted and new stars are formed.

<span class="mw-page-title-main">NGC 3445</span> Galaxy in the constellation Ursa Major

NGC 3445 is a Magellanic spiral galaxy in the constellation Ursa Major. The galaxy lies about 75 million light years away from Earth, which means, given its apparent dimensions, that NGC 3445 is approximately 35,000 light years across. It was discovered by William Herschel on April 8, 1793.

<span class="mw-page-title-main">NGC 1385</span> Galaxy in the constellation Fornax

NGC 1385 is a barred spiral galaxy in the constellation of Fornax. Its velocity with respect to the cosmic microwave background is 1381 ± 9 km/s, which corresponds to a Hubble distance of 20.37 ± 1.43 Mpc. In addition, 30 non redshift measurements give a distance of 15.999 ± 12.131 Mpc. The galaxy was discovered by German-British astronomer William Herschel on 17 November 1784.

References

  1. 1 2 3 4 5 6 7 8 9 "NED results for object NGC 1232". NASA/IPAC Extragalactic Database. Retrieved 2006-11-25.
  2. 1 2 3 "Distance Results for NGC 1232". NASA/IPAC Extragalactic Database. Retrieved 2010-06-22.
  3. ↑ Seligman, Courtney. "NGC Objects: NGC 1200 - 1249". cseligman.com. Retrieved 14 February 2019.
  4. 1 2 3 4 Lima-Costa, F.; Martins, L.P.; Rodríguez-Ardila, A.; Fraga, L. (October 2020). "Spectroscopic study of the HII regions in the NGC 1232 galaxy". Astronomy & Astrophysics. 642: 29. arXiv: 2009.05688 . Bibcode:2020A&A...642A.203L. doi: 10.1051/0004-6361/202038088 .
  5. 1 2 Gamire, Gordon P. (June 2013). "X-Ray Discovery of a Dwarf-galaxy-Galaxy Collision". The Astrophysical Journal. 770 (1): 5. arXiv: 1308.0728 . Bibcode:2013ApJ...770...17G. doi:10.1088/0004-637X/770/1/17. S2CID   85464779 . Retrieved November 12, 2022.
  6. 1 2 3 Soria, Roberto; Pakull, Manfred W. (May 2021). "X-raying the galaxy pair Arp 41: no collision in NGC 1232 and three ultraluminous sources in NGC 1232A". Monthly Notices of the Royal Astronomical Society. 503 (1): 997-1004. arXiv: 2102.08961 . Bibcode:2021MNRAS.503..997S. doi: 10.1093/mnras/stab546 .
  7. 1 2 3 4 Araújo de Souza, Alexandre; Martins, Lucimara, P.; Rodríguez-Ardila, Alberto; Fraga, Luciano (June 2018). "Star Formation Rate Distribution in the Galaxy NGC 1232". The Astronomical Journal. 155 (6): 227–232. arXiv: 1805.09911 . Bibcode:2018AJ....155..234A. doi: 10.3847/1538-3881/aab6b2 . PMID   234. S2CID   119233446.
  8. 1 2 Honig, Z.N.; Reid, M.J. (February 2015). "Characteristics of Spiral Arms in Late-type Galaxies". The Astrophysical Journal. 800 (1): 5387–5394. arXiv: 1412.1012 . Bibcode:2015ApJ...800...53H. doi:10.1088/0004-637X/800/1/53. PMID   53. S2CID   118666575 . Retrieved November 10, 2022.
  9. ↑ "NED results for object NGC 1232A". NASA/IPAC Extragalactic Database. Retrieved 2010-06-22.
  10. ↑ "Distance Results for NGC 1232A". NASA/IPAC Extragalactic Database. Retrieved 2010-06-22.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.