Large Magellanic Cloud

Coordinates: Sky map 05h 23m 34.5s, −69° 45′ 22″
Source: Wikipedia, the free encyclopedia.
(Redirected from
Greater Magellanic Cloud
)
Large Magellanic Cloud
A map of the Large Magellanic Cloud with the brightest features annotated
Observation data (J2000 epoch)
ConstellationDorado/Mensa
Right ascension05h 23m 34s[1]
Declination−69° 45.4′[1]
Distance163,000 light-years (49.97 kpc)[2]
Apparent magnitude (V)0.13[1]
Characteristics
TypeSB(s)m[1]
Mass1×1010 (excluding dark matter), 1.38×1011[3] (including dark matter). M☉
Number of stars20 billion[5]
Size9.86 kpc (32,200 ly)[1]
(diameter; 25.0 mag/arcsec2 B-band isophote)[4]
Apparent size (V)10.75° × 9.17°[1]
Other designations
LMC, ESO 56- G 115, PGC 17223,[1] Nubecula Major[6]

The Large Magellanic Cloud (LMC) is a

dwarf irregular galaxy called the Canis Major Overdensity. Based on the D25 isophote at the B-band (445 nm wavelength of light), the Large Magellanic Cloud is about 9.86 kiloparsecs (32,200 light-years) across.[1][4] It is roughly one-hundredth the mass of the Milky Way[11] and is the fourth-largest galaxy in the Local Group, after the Andromeda Galaxy (M31), the Milky Way, and the Triangulum Galaxy
(M33).

The LMC is classified as a

spiral arms were disrupted, likely by tidal interactions from the Small Magellanic Cloud (SMC) and the Milky Way's gravity.[13]

With a

southern hemisphere of the Earth and from as far north as 20° N. It straddles the constellations Dorado and Mensa and has an apparent length of about 10° to the naked eye, 20 times the Moon's diameter, from dark sites away from light pollution.[14]

The LMC is predicted to merge with the Milky Way in approximately 2.4 billion years.[15]

History of observation

Small part of the Large Magellanic Cloud[16]

Both the Large and Small Magellanic Clouds have been easily visible for southern nighttime observers well back into prehistory. It has been claimed that the first known written mention of the Large Magellanic Cloud was by the

Book of Fixed Stars around 964 AD.[17][18] However, this seems to be a misunderstanding of a reference to some stars south of Canopus which he admits he has not seen.[19][20]

The first confirmed recorded observation was in 1503–1504 by

Coalsack.[21]

Constellation of Dorado: the LMC is the green circle at the south (bottom) of picture

Ferdinand Magellan sighted the LMC on his voyage in 1519 and his writings brought it into common Western knowledge. The galaxy now bears his name.[18] The galaxy and southern end of Dorado are in the current epoch at opposition on about 5 December when thus visible from sunset to sunrise from equatorial points such as Ecuador, the Congos, Uganda, Kenya and Indonesia and for part of the night in nearby months. Above about 28° south, such as most of Australia and South Africa, the galaxy is always sufficiently above the horizon to be considered properly circumpolar, thus during spring and autumn the cloud is also visible much of the night, and the height of winter in June nearly coincides with closest proximity to the Sun's apparent position.

Measurements with the Hubble Space Telescope, announced in 2006, suggest the Large and Small Magellanic Clouds may be moving too quickly to be orbiting the Milky Way.[22]

Astronomers discovered a new black hole inside the Large Magellanic Cloud in November 2021 using the

better source needed
]

Geometry

ESO's VISTA image of the LMC

The Large Magellanic Cloud has a prominent central bar and

spiral arm.[24] The central bar seems to be warped so that the east and west ends are nearer the Milky Way than the middle.[25] In 2014, measurements from the Hubble Space Telescope made it possible to determine a rotation period of 250 million years.[26]

The LMC was long considered to be a planar galaxy that could be assumed to lie at a single distance from the Solar System. However, in 1986, Caldwell and Coulson

star clusters in the LMC, Schommer et al.[33] measured velocities for ~80 clusters and found that the LMC's cluster system has kinematics consistent with the clusters moving in a disk-like distribution. These results were confirmed by Grocholski et al.,[34]
who calculated distances to a sample of clusters and showed that the cluster system is distributed in the same plane as the field stars.

Distance

Location of the Large Magellanic Cloud with respect to the Milky Way and other satellite galaxies

Distance to the LMC has been calculated using

standard candles; Cepheid variables are one of the most popular. These have been shown to have a relationship between their absolute luminosity and the period over which their brightness varies. However the variable of metallicity may also need to be taken as a component of this as consensus is this likely affects their period-luminosity relations. Unfortunately, those in the Milky Way typically used to calibrate the relation are more metal-rich than those found in the LMC.[35]

Modern

supernova 1987A are also geometric measurements, without any stellar models or assumptions.[citation needed
]

In 2006, the Cepheid absolute luminosity was re-calibrated using Cepheid variables in the galaxy Messier 106 that cover a range of metallicities.[8] Using this improved calibration, they find an absolute distance modulus of , or 48 kpc (160,000 light-years). This distance has been confirmed by other authors.[9][10]

By cross-correlating different measurement methods, one can bound the distance; the residual errors are now less than the estimated size parameters of the LMC.

The results of a study using late-type eclipsing binaries to determine the distance more accurately was published in the scientific journal Nature in March 2013. A distance of 49.97 kpc (163,000 light-years) with an accuracy of 2.2% was obtained.[2]

Features

Two very different glowing gas clouds in the Large Magellanic Cloud, NGC 2014 (red) and NGC 2020 (blue)[36]

Like many

irregular galaxies, the LMC is rich in gas and dust, and is currently undergoing vigorous star formation activity.[37] It holds the Tarantula Nebula
, the most active star-forming region in the Local Group.

The LMC has a wide range of galactic objects and phenomena that make it known as an "astronomical treasure-house, a great celestial laboratory for the study of the growth and evolution of the stars", per

Australian High Court Justice Lionel Murphy's interest in science and its perceived resemblance to his large nose.[40]

NGC 1783 is one of the biggest globular clusters in the Large Magellanic Cloud[41]

A bridge of gas connects the Small Magellanic Cloud (SMC) with the LMC, which evinces tidal interaction between the galaxies.[42] The Magellanic Clouds have a common envelope of neutral hydrogen, indicating that they have been gravitationally bound for a long time. This bridge of gas is a star-forming site.[43]

X-ray sources

Small and Large Magellanic Clouds over Paranal Observatory

No X-rays above background were detected from either cloud during the September 20, 1966,

Nike-Tomahawk rocket flight nor that of two days later.[44] The second took off from Johnston Atoll at 17:13 UTC and reached an apogee of 160 km (99 mi), with spin-stabilization at 5.6 rps.[45] The LMC was not detected in the X-ray range 8–80 keV.[45]

Another was launched from same atoll at 11:32 UTC on October 29, 1968, to scan the LMC for X-rays.

ergs/s.[46] An X-ray astronomy instrument was carried aboard a Thor missile launched from the same atoll on September 24, 1970, at 12:54 UTC and altitudes above 300 km (190 mi), to search for the Small Magellanic Cloud and to extend observation of the LMC.[49] The source in the LMC appeared extended and contained star ε Dor. The X-ray luminosity (Lx) over the range 1.5–12 keV was 6×1031 W (6×1038 erg/s).[49]

The Large Magellanic Cloud (LMC) appears in the constellations

LMXB) in the LMC.[51]

DEM L316 in the Cloud consists of two supernova remnants.[52] Chandra X-ray spectra show that the hot gas shell on the upper left has an abundance of iron. This implies that the upper-left SNR is the product of a Type Ia supernova; much lower such abundance in the lower remnant belies a Type II supernova.[52]

A 16 ms X-ray pulsar is associated with SNR 0538-69.1.[53] SNR 0540-697 was resolved using ROSAT.[54]

Gallery

  • Part of the SMASH dataset showing a wide-angle view of the Large Magellanic Cloud[55]
    Part of the SMASH dataset showing a wide-angle view of the Large Magellanic Cloud[55]
  • Large Magellanic Cloud as photographed by an amateur astronomer. Unrelated stars have been edited out.
    Large Magellanic Cloud as photographed by an amateur astronomer. Unrelated stars have been edited out.
  • Large Magellanic Cloud rendered from Gaia EDR3
    Large Magellanic Cloud rendered from Gaia EDR3
  • Large Magellanic Cloud rendered from Gaia EDR3 without foreground stars
    Large Magellanic Cloud rendered from Gaia EDR3 without foreground stars
  • Revisiting a Celestial Fireworks Display Shreds, from the Wide Field Planetary Camera 2. The delicate sheets and intricate filaments are debris from the cataclysmic death of a massive star that once lived in the LMC.[56]
    Revisiting a Celestial Fireworks Display Shreds, from the
    Wide Field Planetary Camera 2. The delicate sheets and intricate filaments are debris from the cataclysmic death of a massive star that once lived in the LMC.[56]
  • DEM L316A is located some 160,000 light-years away in the Large Magellanic Cloud[57]
    DEM L316A is located some 160,000 light-years away in the Large Magellanic Cloud[57]

Notes

  1. ^ a b c d e f g h "NASA/IPAC Extragalactic Database". Results for Large Magellanic Cloud. Retrieved 29 July 2022.
  2. ^
    S2CID 4417699
    .
  3. doi:10.1093/mnras/stz1371
    .
  4. ^
    Bibcode:1991rc3..book.....D
    .
  5. ISBN 978-3-03-010380-4
    .
  6. Bibcode:1954ASPL....7....9B
    .
  7. S2CID 854729
    .
  8. ^
    S2CID 15728812
    .
  9. ^
    S2CID 119263173
    .
  10. ^
    Bibcode:2011JAVSO..39..122M
    .
  11. ^ "Magellanic Cloud". Encyclopædia Britannica. 2009. Retrieved 2009-08-30.
  12. ISBN 9780321595584
    .
  13. S2CID 118462693
    .
  14. ^ Sessions, Larry (December 8, 2021). "The Magellanic Clouds, our galactic neighbors". EarthSky. Retrieved 2013-07-17.
  15. ISSN 0035-8711
    .
  16. ^ "Cloaked in red". ESA / HUBBLE. 24 February 2014. Retrieved 12 March 2014.
  17. ^ "Observatoire de Paris (Abd-al-Rahman Al Sufi)". Retrieved 2007-04-19.
  18. ^ a b "Observatoire de Paris (LMC)". Retrieved 2007-04-19.
  19. ISBN 9781441981615
    , retrieved November 13, 2019
  20. ^ Ridpath, Ian. Star Tales – al-Sufi's nebulae. Online edition. Retrieved 2021-09-15.
  21. ^ "Observatoire de Paris (Amerigo Vespucci)". Retrieved 2007-04-19.
  22. ^ "Press release: Magellanic Clouds May Be Just Passing Through". Harvard University. January 9, 2007.
  23. ^ Ashley Strickland (11 November 2021). "Hidden black hole discovered in our neighboring galaxy". CNN. Retrieved 2021-11-18.
  24. ISBN 0-521-59270-4
    .
  25. S2CID 4368706
    .
  26. ^ "Precisely determined rotation rate of this galaxy will blow your mind". Science Recorder. Archived from the original on 2014-02-21.
  27. doi:10.1093/mnras/218.2.223
    .
  28. S2CID 15818077
    .
  29. S2CID 121615519
    .
  30. ^
    S2CID 15850335
    .
  31. S2CID 7266377
    .
  32. ^
    doi:10.1093/mnras/stac595
    .
  33. doi:10.1086/116074
    .
  34. S2CID 14921511
    .
  35. Bibcode:2006MmSAI..77..156M
    .
  36. ^ "The Odd Couple". ESO Press Release. Retrieved 8 August 2013.
  37. ISBN 0-07-228249-5
    .
  38. ISBN 0-486-23567-X
    .
  39. ^ Burnham (1978), 840–848.
  40. ISSN 0004-637X
    .
  41. ^ "A youthful cluster". ESA/Hubble Picture of the Week. Retrieved 24 August 2015.
  42. ^ Mathewson D. S., Ford V. L. (1984). S. van den Bergh; K. S. de Boer (eds.). "Structure and Evolution of the Magellanic Clouds". IAU Symposium. 108. Reidel, Dordrecht: 125.
  43. S2CID 8240730
    .
  44. doi:10.1086/149312
    .
  45. ^
    doi:10.1086/149343
    .
  46. ^
    doi:10.1086/180322
    .
  47. S2CID 4187949
    .
  48. doi:10.1086/110966
    .
  49. ^
    doi:10.1086/180773
    .
  50. doi:10.1086/181564
    .
  51. Bibcode:1989A&A...213...97B
    .
  52. ^
    S2CID 17863461
    .
  53. S2CID 15812971
    .
  54. ISSN 0004-6280
    .
  55. ^ "Dark Energy Camera Snaps Deepest Photo yet of Galactic Siblings". noirlab.edu. Retrieved 19 December 2020.
  56. ^ "Revisiting a Celestial Fireworks Display". Retrieved 2023-08-24.
  57. ^ "A long-dead star". www.spacetelescope.org. Retrieved 25 July 2016.

External links

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