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Sculptor Galaxy

Not to be confused with the Sculptor Dwarf Galaxy or the Sculptor Dwarf Irregular Galaxy.

The Sculptor Galaxy (also known as the Silver Coin Galaxy, Silver Dollar Galaxy, NGC 253, or Caldwell 65) is an intermediate spiral galaxy in the constellation Sculptor. The Sculptor Galaxy is a starburst galaxy, which means that it is currently undergoing a period of intense star formation.

Sculptor Galaxy
Observation data (J2000 epoch)
ConstellationSculptor
Right ascension00h 47m 33.13s[1]
Declination−25° 17′ 17.1″[1]
Redshift0.000807[1]
Heliocentric radial velocity242 ± 1 km/s [1]
Distance11.4 ± 0.7 Mly
   (3.5 ± 0.2 Mpc)[2]
Apparent magnitude (V)8.0[1]
Characteristics
TypeSAB(s)c[1]
Size36.96 kiloparsecs (120,500 light-years)
(diameter; D27 isophote)
Apparent size (V)27′.5 × 6′.8[1]
Other designations
Silver Coin Galaxy,[1] Silver Dollar Galaxy,[3] NGC 253,[1] UGCA 13,[1] PGC 2789[1] Caldwell 65

Observation

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Observational history

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The galaxy was discovered by Caroline Herschel in 1783 during one of her systematic comet searches.[4][5] About half a century later, John Herschel observed it using his 18-inch metallic mirror reflector at the Cape of Good Hope.[5] He wrote: "very bright and large (24′ in length); a superb object.... Its light is somewhat streaky, but I see no stars in it except 4 large and one very small one, and these seem not to belong to it, there being many near..."[5]

In 1961, Allan Sandage wrote in the Hubble Atlas of Galaxies that the Sculptor Galaxy is "the prototype example of a special subgroup of Sc systems....photographic images of galaxies of the group are dominated by the dust pattern. Dust lanes and patches of great complexity are scattered throughout the surface. Spiral arms are often difficult to trace.... The arms are defined as much by the dust as by the spiral pattern."[6] Bernard Y. Mills, working out of Sydney, discovered that the Sculptor Galaxy is also a fairly strong radio source.[5]

In 1998, the Hubble Space Telescope took a detailed image of NGC 253.[7]

Amateur

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As one of the brightest galaxies in the sky, the Sculptor Galaxy can be seen through binoculars and is near the star Beta Ceti. It is considered one of the most easily viewed galaxies in the sky after the Andromeda Galaxy.[5][8]

The Sculptor Galaxy is a good target for observation with a telescope with a 300 mm diameter or larger.[8] In such telescopes, it appears as a galaxy with a long, oval bulge and a mottled galactic disc.[8] Although the bulge appears only slightly brighter than the rest of the galaxy, it is fairly extended compared to the disk.[8] In 400 mm scopes and larger, a dark dust lane northwest of the nucleus is visible, and over a dozen faint stars can be seen superimposed on the bulge.[8] Some people claim to have observed the galaxy with the unaided eye under exceptional viewing conditions.

Features

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Three-dimensional simulation of ALMA observations of the outflows.[9]
 
Detail of NGC 253 by Hubble Space Telescope. (Credit: HST/NASA/ESA).

The Sculptor Galaxy is located at the center of the Sculptor Group, one of the nearest groups of galaxies to the Milky Way.[10] The Sculptor Galaxy (the brightest galaxy in the group and one of the intrinsically brightest galaxies in the vicinity of ours, only surpassed by the Andromeda Galaxy and the Sombrero Galaxy[11]) and the companion galaxies NGC 247, PGC 2881, PGC 2933, Sculptor-dE1, and UGCA 15 form a gravitationally-bound core near the center of the group. Most other galaxies associated with the Sculptor Group are only weakly gravitationally bound to this core.[10][12]

Starburst

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NGC 253's starburst has created several super star clusters on NGC 253's center (discovered with the aid of the Hubble Space Telescope): one with a mass of 1.5×106 solar masses, and absolute magnitude of at least −15, and two others with 5×104 solar masses and absolute magnitudes around −11;[13] later studies have discovered an even more massive cluster heavily obscured by NGC 253's interstellar dust with a mass of 1.4×107 solar masses, an age of around 5.7×106 years, and rich in Wolf-Rayet stars.[14] The super star clusters are arranged in an ellipse around the center of NGC 253, which from the Earth's perspective appears as a flat line.[15]

Star formation is also high in the northeast of NGC 253's disk, where a number of red supergiant stars can be found, and in its halo there are young stars as well as some amounts of neutral hydrogen. This, along with other peculiarities found in NGC 253, suggest that a gas-rich dwarf galaxy collided with it 200 million years ago, disturbing its disk and starting the present starburst.[16]

As happens in other galaxies suffering strong star formation such as Messier 82, NGC 4631, or NGC 4666, the stellar winds of the massive stars produced in the starburst as well as their deaths as supernovae have blown out material to NGC 253's halo in the form of a superwind that seems to be inhibiting star formation in the galaxy.[17]

Novae and Supernovae

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Although supernovae are generally associated with starburst galaxies, only one has been detected within the Sculptor Galaxy. SN 1940E (type unknown, mag. 14)[18] was discovered by Fritz Zwicky on 22 November 1940, located approximately 54″ southwest of the galaxy's nucleus.[19]

NGC 253 is close enough that classical novae can also be detected. The first confirmed nova in this galaxy was discovered by BlackGEM at magnitude 19.6 on 12 July 2024, and designated AT 2024pid.[20]

Central black hole

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Research suggests the presence of a supermassive black hole in the center of this galaxy with a mass estimated to be 5 million times that of the Sun, which is slightly heavier than Sagittarius A*.[21]

Distance estimates

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At least two techniques have been used to measure distances to Sculptor in the past ten years.

Using the planetary nebula luminosity function method, an estimate of 10.89 +0.85
−1.24 million light years (or Mly; 3.34 +0.26
−0.38 Megaparsecs, or Mpc) was achieved in 2005.[2]

The Sculptor Galaxy is close enough that the tip of the red-giant branch (TRGB) method may also be used to estimate its distance. The estimated distance to Sculptor using this technique in 2004 yielded 12.8±1.2 Mly (3.94±0.37 Mpc).[22][23]

A weighted average of the most reliable distance estimates gives a distance of 11.4±0.7 Mly (3.5±0.2 Mpc).[2]

Satellite

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An international team of researchers has used the Subaru Telescope to identify a faint dwarf galaxy disrupted by NGC 253. The satellite galaxy is called NGC 253-dw2 and may not survive its next passage by its much larger host. The host galaxy may suffer some damage too if the dwarf is massive enough.[24] The interplay between the two galaxies is responsible for the disturbance in NGC 253's structure.[25]

See also

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References

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  1. ^ a b c d e f g h i j k "NASA/IPAC Extragalactic Database". Results for NGC 253. Retrieved 2006-11-25.
  2. ^ a b c Rekola, R.; Richer, M. G.; McCall, Marshall L.; Valtonen, M. J.; Kotilainen, J. K.; Flynn, Chris (2005). "Distance to NGC 253 based on the planetary nebula luminosity function". Monthly Notices of the Royal Astronomical Society. 361 (1): 330–336. Bibcode:2005MNRAS.361..330R. doi:10.1111/j.1365-2966.2005.09166.x.
  3. ^ Nemiroff, R.; Bonnell, J., eds. (2006-04-21). "NGC 253: Dusty Island Universe". Astronomy Picture of the Day. NASA. Retrieved 2010-12-04.
  4. ^ Dreyer, J. L. E. (1888). "A New General Catalogue of Nebulae and Clusters of Stars, being the Catalogue of the late Sir John F.W. Herschel, Bart., revised, corrected, and enlarged". Memoirs of the Royal Astronomical Society. 49: 1–237. Bibcode:1888MmRAS..49....1D.
  5. ^ a b c d e Burnham, Robert (1978). Burnham's Celestial Handbook: An Observer's Guide to the Universe Beyond the Solar System. Vol. Three, Pavo Through Vulpecula. Dover Publications, Inc. p. 1736. ISBN 978-0-486-24065-7.
  6. ^ Sandage, Allan (1961). The Hubble Atlas of Galaxies. Washington: Carnegie Institution. Bibcode:1961hag..book.....S. ISBN 978-0-87279-629-4.
  7. ^ "HubbleSite NewsCenter". Results for NGC 253. Retrieved 2007-04-05.
  8. ^ a b c d e Kepple, George Robert; Sanner, Glen W. (1998). The Night Sky Observer's Guide. Vol. 2. Willmann-Bell, Inc. pp. 365, 371. ISBN 978-0-943396-60-6.
  9. ^ "Starburst to Star Bust". European Southern Observatory. 24 July 2013. Retrieved 15 August 2013.
  10. ^ a b Karachentsev, I. D. (2005). "The Local Group and Other Neighboring Galaxy Groups". The Astronomical Journal. 129 (1): 178–188. arXiv:astro-ph/0410065. Bibcode:2005AJ....129..178K. doi:10.1086/426368. S2CID 119385141.
  11. ^ Karachentsev, Igor D.; Karachentseva, Valentina E.; Huchtmeier, Walter K.; Makarov, Dmitry I. (2003). "A Catalog of Neighboring Galaxies". The Astronomical Journal. 127 (4): 2031–2068. Bibcode:2004AJ....127.2031K. doi:10.1086/382905.
  12. ^ Karachentsev, I. D.; Grebel, E. K.; Sharina, M. E.; Dolphin, A. E.; et al. (2003). "Distances to nearby galaxies in Sculptor". Astronomy and Astrophysics. 404 (1): 93–111. arXiv:astro-ph/0302045. Bibcode:2003A&A...404...93K. doi:10.1051/0004-6361:20030170. S2CID 54977869.
  13. ^ Watson, A. M.; Gallagher, J. S. III; Holtzman, J. A.; Hester, J. J.; et al. (1996). "The Discovery of Young, Luminous, Compact Stellar Clusters in the Starburst Galaxy NGC 253" (PDF). The Astronomical Journal. 112 (2): 534. Bibcode:1996AJ....112..534W. doi:10.1086/118032.
  14. ^ Kornei, Katherine A.; McCrady, Nate (2009). "A Young Super Star Cluster in the Nuclear Region of NGC 253". The Astrophysical Journal. 697 (2): 1180–1186. arXiv:0902.4027. Bibcode:2009ApJ...697.1180K. doi:10.1088/0004-637X/697/2/1180. S2CID 18960325.
  15. ^ Levy, Rebecca C.; Bolatto, Alberto D.; Leroy, Adam K.; Sormani, Mattia C.; Emig, Kimberly L.; Gorski, Mark; Lenkić, Laura; Mills, Elisabeth A. C.; Tarantino, Elizabeth; Teuben, Peter; Veilleux, Sylvain; Walter, Fabian (2022). "The Morpho-kinematic Architecture of Super Star Clusters in the Center of NGC 253". The Astrophysical Journal. 935 (1): 19. arXiv:2206.04700. Bibcode:2022ApJ...935...19L. doi:10.3847/1538-4357/ac7b7a. S2CID 249605852.
  16. ^ Davidge, T. J. (2010). "Shaken, Not Stirred: The Disrupted Disk of the Starburst Galaxy NGC 253". The Astrophysical Journal. 725 (1): 1342–1365. arXiv:1011.3006. Bibcode:2010ApJ...725.1342D. doi:10.1088/0004-637X/725/1/1342. S2CID 118649411.
  17. ^ Bolatto, Alberto D.; Warren, Steven R.; Leroy, Adam K.; Walter, Fabian; et al. (2013). "Suppression of star formation in the galaxy NGC 253 by a starburst-driven molecular wind". Nature. 499 (7459): 450–453. arXiv:1307.6259. Bibcode:2013Natur.499..450B. doi:10.1038/nature12351. PMID 23887428. S2CID 4366091.
  18. ^ "SN 1940E". Transient Name Server. IAU. Retrieved 27 November 2024.
  19. ^ Barbon, R.; Cappellaro, E.; Ciatti, F.; Turatto, M.; Kowal, C. T. (1984). "A revised supernova catalogue". Astronomy & Astrophysics Supplement Series. 58: 735–750. Bibcode:1984A&AS...58..735B.
  20. ^ "AT 2024pid". Transient Name Server. IAU. Retrieved 27 November 2024.
  21. ^ "Black Hole Naps Amidst Stellar Chaos". Jet Propulsion Laboratory. NASA. June 11, 2013.
  22. ^ Karachentsev, Igor D.; Karachentseva, Valentina E.; Hutchmeier, Walter K.; Makarov, Dmitry I. (2004). "A Catalog of Neighboring Galaxies". The Astronomical Journal. 127 (4): 2031–2068. Bibcode:2004AJ....127.2031K. doi:10.1086/382905.
  23. ^ Karachentsev, I. D.; Kashibadze, O. G. (2006). "Masses of the local group and of the M81 group estimated from distortions in the local velocity field". Astrophysics. 49 (1): 3–18. Bibcode:2006Ap.....49....3K. doi:10.1007/s10511-006-0002-6. S2CID 120973010.
  24. ^ "Galactic Space Oddity Discovered". Subaru Telescope. National Astronomical Observatory of Japan. February 8, 2016. Retrieved February 9, 2016.
  25. ^ Romanowsky, Aaron J.; Martínez-Delgado, David; Martin, Nicolas F.; Morales, Gustavo; et al. (2016). "Satellite accretion in action: a tidally disrupting dwarf spheroidal around the nearby spiral galaxy NGC 253". Monthly Notices of the Royal Astronomical Society. 456 (1): 103–107. arXiv:1512.03815. Bibcode:2016MNRAS.457L.103R. doi:10.1093/mnrasl/slv207.
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