Sculptor Galaxy

Coordinates: Sky map 00h 47m 33s, −25° 17′ 18″
Source: Wikipedia, the free encyclopedia.
Not to be confused with the Sculptor Dwarf Galaxy or the Sculptor Dwarf Irregular Galaxy.
Sculptor Galaxy
Mly
   (3.5 ± 0.2 Mpc)[2]
Apparent magnitude (V)8.0[1]
Characteristics
TypeSAB(s)c[1]
Size~90,000 ly (diameter)
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

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.

Observation

Observational history

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,

radio source.[5]

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

Amateur

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]

Features

Three-dimensional simulation of ALMA observations of the outflows.[9]
ESA
).

The Sculptor Galaxy is located at the center of the

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

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]

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]

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. It was discovered in November 1940.[18]

Central black hole

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*.[19]

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 million light years (or Mly; 3.34 +0.26
−0.38 Megaparsecs, or Mpc) was achieved in 2006.[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).[20][21]

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

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 heavy enough.[22] The interplay between the two galaxies is responsible for the disturbance in NGC 253's structure.[23]

See also

  • Globular cluster NGC 288, 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. 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".
    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. Bibcode:1888MmRAS..49....1D
    .
  5. ^
    ISBN 978-0-486-24065-7
    .
  6. ISBN 978-0-87279-629-4
    .
  7. ^ "HubbleSite NewsCenter". Results for NGC 253. Retrieved 2007-04-05.
  8. ^
    ISBN 978-0-943396-60-6
    .
  9. ^ "Starburst to Star Bust". European Southern Observatory. 24 July 2013. Retrieved 15 August 2013.
  10. ^
    S2CID 119385141
    .
  11. doi:10.1086/382905
    .
  12. S2CID 54977869
    .
  13. doi:10.1086/118032
    .
  14. S2CID 18960325
    .
  15. S2CID 249605852
    .
  16. S2CID 118649411
    .
  17. S2CID 4366091
    .
  18. Bibcode:1984A&AS...58..735B
    .
  19. ^ "Black Hole Naps Amidst Stellar Chaos". Jet Propulsion Laboratory. NASA. June 11, 2013.
  20. doi:10.1086/382905
    .
  21. S2CID 120973010
    .
  22. ^ "Galactic Space Oddity Discovered". Subaru Telescope. National Astronomical Observatory of Japan. February 8, 2016. Retrieved February 9, 2016.
  23. doi:10.1093/mnrasl/slv207
    .

External links

Wikimedia Commons has media related to NGC 253.


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