Sculptor Galaxy
The Sculptor Galaxy (NGC 253) 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 while doing one of her systematic comet searches.[1][2] About a half century later, John Herschel while at the Cape of Good Hope observed it using his 18 inch metallic mirror reflector.[2] He then 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..."[2]
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."[3] B. Y. Mills, working out of Sydney, discovered that the Sculptor Galaxy is also a fairly strong radio source.[2]
In 1998 the hubble space telescope took a close up of NGC 253.[4]
Supernovae
Although supernovae are generally associated with starburst galaxies, only one supernova has been detected within the Sculptor Galaxy[5]. The supernova, named SN 1940E, is located approximately 50′ southwest of the galaxy's nucleus[6]. It was discovered on November 1940[6].
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.[7]
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).[8][9]
Combining the most reliable distance estimates to get a weighted average gives a distance of 11.4 ± 0.7 Mly (3.5 ± 0.2 Mpc).[7]
Galaxy group information
The Sculptor Galaxy is located at the center of the Sculptor Group, which is one of the nearest groups of galaxies to the Milky Way[10] The Sculptor Galaxy, which is the brightest galaxy in this 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.[11][10]
Amateur observation
Observations with binoculars
As one of the brightest galaxies in the sky, the Sculptor Galaxy is viewable through binoculars. It is considered to be one of the most easily viewed galaxies in the sky after the Andromeda Galaxy[12][2]
Observations with amateur telescopes
The Sculptor Galaxy is a good target for observation with a telescope with a 300 mm diameter or larger.[12] As seen through such telescopes, it appears as a galaxy with a long, oval bulge and a mottled disk.[12] Although the bulge appears only slightly brighter than the rest of the galaxy, it is fairly extended compared to the disk.[12] In 400 mm scopes and larger, a dark dust lane northwest of the nucleus is visible, and over a dozen faint stars may be seen superimposed on the bulge.[12]
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
See also
- Globular cluster NGC 288 is located 1°.8 south-southeast of the Sculptor Galaxy.
References
- ^ 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.
- ^ 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.
- ^ Sandage, Allan (1961). The Hubble atlas of galaxies. Washington: Carnegie Institution.
- ^ "HubbleSite NewsCenter". Results for NGC 253. Retrieved 2007-04-05.
- ^ Cite error: The named reference
nedwas invoked but never defined (see the help page). - ^ a b R. Barbon, E. Cappellaro, F. Ciatti, M. Turatto, C. T. Kowal (1984). "A revised supernova catalogue". Astronomy & Astrophysics Supplement Series. 58: 735–750.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ a b Cite error: The named reference
Rekolaetal2005was invoked but never defined (see the help page). - ^ I. D. Karachentsev, V. E. Karachentseva, W. K. Hutchmeier, D. I. Makarov (2004). "A Catalog of Neighboring Galaxies". Astronomical Journal. 127: 2031–2068.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ 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.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ a b I. D. Karachentsev (2005). "The Local Group and Other Neighboring Galaxy Groups". Astronomical Journal. 129: 178–188.
- ^ 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: 93–111.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ a b c d e Kepple, George Robert (1998). The Night Sky Observer's Guide, Volume 2. Willmann-Bell, Inc. pp. 365, 371. ISBN 0-943396-60-3.
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