Sculptor Galaxy

Sculptor Galaxy
The Sculptor Galaxy taken with the ESO VISTA telescope at the Paranal Observatory in Chile.
Observation data (J2000 epoch)
Constellation	Sculptor
Right ascension	00h 47m 33s[1]
Declination	-25° 17′ 18″[1]
Redshift	0.000811[1]
Helio radial velocity	243 ± 2 km/s [1]
Distance	11.4 ± 0.7 Mly    (3.5 ± 0.2 Mpc)[2]
Type	SAB(s)c[1]
Apparent dimensions (V)	27′.5 × 6′.8[1]
Apparent magnitude (V)	8.0[1]
Other designations
Silver Coin Galaxy,[1] Silver Dollar Galaxy,[3] NGC 253,[1] UGCA 13,[1] PGC 2789[1] Caldwell 65[4]
See also: Galaxy, List of galaxies

The Sculptor Galaxy (also known as the Silver Coin or 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.

Observational history

The galaxy was discovered by Caroline Herschel in 1783 during one of her systematic comet searches.^[5][6] About half a century later, John Herschel observed it using his 18 inch metallic mirror reflector at the Cape of Good Hope.^[6] 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..."^[6]

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."^[7] B. Y. Mills, working out of Sydney, discovered that the Sculptor Galaxy is also a fairly strong radio source.^[6]

In 1998 the Hubble Space Telescope took a detailed image of NGC 253.^[8]

Supernovae

Although supernovae are generally associated with starburst galaxies, only one supernova has been detected within the Sculptor Galaxy.^[1] The supernova, named SN 1940E, is located approximately 54″ southwest of the galaxy's nucleus.^[9] It was discovered in November 1940.^[9]

Recent distance estimates

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 Mly (3.34 +0.26
−0.38 Mpc) was achieved in 2006.^[2]

Sculptor 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).^[10][11]

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

Galaxy group information

The Sculptor Galaxy is located at the center of the Sculptor Group, one of the nearest groups of galaxies to the Milky Way.^[12] The Sculptor Galaxy (the brightest galaxy in the group) 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.^[12][13]

Amateur observation

Observations with binoculars

As one of the brightest galaxies in the sky, the Sculptor Galaxy can be seen through binoculars. It is considered one of the most easily viewed galaxies in the sky after the Andromeda Galaxy.^[6][14]

Observations with amateur telescopes

The Sculptor Galaxy is a good target for observation with a telescope with a 300 mm diameter or larger.^[14] In such telescopes, it appears as a galaxy with a long, oval bulge and a mottled disk.^[14] Although the bulge appears only slightly brighter than the rest of the galaxy, it is fairly extended compared to the disk.^[14] 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.^[14]

Gallery

• 

  NGC 253. (Courtesy Hunter Wilson)

• 

  NGC253 from 24 inch telescope on Mt. Lemmon, AZ. (Courtesy Joseph D. Schulman)

• 

  Spiral Galaxy NGC 253. (Credit: ESO)

• 

  Detail of NGC 253 by Hubble Space Telescope. (Credit: HST/NASA/ESA)

In popular culture

In the American television series The Event, the episode "Inostranka" reveals that the earthbound extraterrestrials originate from the Sculptor Galaxy.

See also

• Globular cluster NGC 288 is located 1°.8 south-southeast of the Sculptor Galaxy.
• 2MASX J00482185-2507365 occulting pair discovered while photographing NGC 253

References

1. ^ ^{a b c d e f g h i j k l} "NASA/IPAC Extragalactic Database". Results for NGC 253. http://nedwww.ipac.caltech.edu/cgi-bin/nph-objsearch?objname=NGC+253&img_stamp=yes&extend=no. 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. ^ "NGC 253: Dusty Island Universe". NASA Astro Pic of the Day. 2006-04-21. http://apod.nasa.gov/apod/ap060421.html. Retrieved 2010-12-04. 
4. ^ O'Meara, Stephen James (2002). The Caldwell Objects. Cambridge University Press. ISBN 0-521-82796-5. 
5. ^ 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. 
6. ^ ^{a b c d e} Burnham, Robert (1978). Burnham's Celestial Handbook; An Observers Guide to the Universe Beyond the Solar System; Volume Three, Pavo Through Vulpecula. Dover Publications, Inc.. p. 1736. ISBN 0-486-24065-7. 
7. ^ Sandage, Allan (1961). The Hubble atlas of galaxies. Washington: Carnegie Institution. ISBN 0872796299. http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1961hag..book.....S. 
8. ^ "HubbleSite NewsCenter". Results for NGC 253. http://hubblesite.org/newscenter/archive/releases/1998/42/image/a. Retrieved 2007-04-05. 
9. ^ ^{a b} R. Barbon, E. Cappellaro, F. Ciatti, M. Turatto, C. T. Kowal; Cappellaro; Ciatti; Turatto; Kowal (1984). "A revised supernova catalogue". Astronomy & Astrophysics Supplement Series 58: 735–750. Bibcode 1984A&AS...58..735B. 
10. ^ I. D. Karachentsev, V. E. Karachentseva, W. K. Hutchmeier, D. I. Makarov (2004). "A Catalog of Neighboring Galaxies". Astronomical Journal 127 (4): 2031–2068. Bibcode 2004AJ....127.2031K. doi:10.1086/382905. 
11. ^ 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. 
12. ^ ^{a b} I. D. Karachentsev (2005). "The Local Group and Other Neighboring Galaxy Groups". Astronomical Journal 129 (1): 178–188. arXiv:astro-ph/0410065. Bibcode 2005AJ....129..178K. doi:10.1086/426368. 
13. ^ I. D. Karachentsev, E. K. Grebel, M. E. Sharina, A. E. Dolphin, D. Geisler, P. Guhathakrta, P. W. Hodge, V. E. Karachentseva, A. Sarajedini, P. Seitzer (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. 
14. ^ ^{a b c d e} Kepple, George Robert; Glen W. Sanner (1998). The Night Sky Observer's Guide, Volume 2. Willmann-Bell, Inc.. pp. 365, 371. ISBN 0-943396-60-3. 

External links

• STScI news release: Hubble Probes the Violent Birth of Stars in Galaxy NGC 253
• STScI news release: Behind a Dusty Veil Lies a Cradle of Star Birth
• Sculptor Galaxy on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images

Coordinates: 00^h 47^m 33^s, −25° 17′ 18″