Lagoon Nebula

The Lagoon Nebula (catalogued as Messier 8 or M8, NGC 6523, Sharpless 25, RCW 146, and Gum 72) is a giant interstellar cloud in the constellation Sagittarius. It is classified as an emission nebula and as an H II region.

Lagoon Nebula
Emission nebula
H II region
M8, the Lagoon Nebula
Observation data: J2000 epoch
Right ascension18h 03m 37s[1]
Declination−24° 23′ 12″[1]
Distance4,100[2] ly   (1,250 pc)
Apparent magnitude (V)6.0
Apparent dimensions (V)90 × 40 arcmins
ConstellationSagittarius
Physical characteristics
Radius55 × 20 ly
DesignationsSharpless 25, RCW 146, Gum 72
M8 contains:
    NGC 6523, NGC 6530,[1]
    Hourglass nebula[3]

The Lagoon Nebula was discovered by Giovanni Hodierna before 1654[4] and is one of only two star-forming nebulae faintly visible to the eye from mid-northern latitudes. Seen with binoculars, it appears as a distinct oval cloudlike patch with a definite core. Within the nebula is the open cluster NGC 6530.[5]

Characteristics

The Lagoon Nebula is estimated to be between 4,000-6,000 light-years away from the Earth. In the sky of Earth, it spans 90' by 40', which translates to an actual dimension of 110 by 50 light years. Like many nebulas, it appears pink in time-exposure color photos but is gray to the eye peering through binoculars or a telescope, human vision having poor color sensitivity at low light levels. The nebula contains a number of Bok globules (dark, collapsing clouds of protostellar material), the most prominent of which have been catalogued by E. E. Barnard as B88, B89 and B296. It also includes a funnel-like or tornado-like structure caused by a hot O-type star that emanates ultraviolet light, heating and ionizing gases on the surface of the nebula. The Lagoon Nebula also contains at its centre a structure known as the Hourglass Nebula (so named by John Herschel), which should not be confused with the better known Engraved Hourglass Nebula in the constellation of Musca. In 2006 the first four Herbig–Haro objects were detected within the Hourglass, also including HH 870. This provides the first direct evidence of active star formation by accretion within it.[2]

In fiction

In the Battlestar Galactica (2004) season two episode "Home", M8 was identified as a guide to Earth.

Further information: Nebulae in fiction § Lagoon Nebula

See also
Lagoon Nebula (M8) and Trifid Nebula (M20) - by Gary JONES
  • Amateur photo of the Lagoon Nebula by Astrodymium.
  • Lagoon and Trifid nebula from Los Angeles by Amateur Astronomer Alex Weinstein.
  • Lagoon in narrowband by Dylan O'Donnell.

References
  1. "M 8". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2006-11-15.
  2. Arias, J. I.; Barbá, R. H.; Maíz Apellániz, J.; Morrell, N. I.; Rubio, M. (2006). "The infrared Hourglass cluster in M8". Monthly Notices of the Royal Astronomical Society. 366 (3): 739–757. arXiv:astro-ph/0506552. Bibcode:2006MNRAS.366..739A. doi:10.1111/j.1365-2966.2005.09829.x.
  3. "SIMBAD Astronomical Database". Results for Hourglass Nebula. Retrieved 2006-12-22.
  4. Kronberg, Guy McArthur, Hartmut Frommert, Christine. "Messier Object 8". messier.seds.org. Retrieved 11 April 2018.
  5. N. F. H. Tothill; Marc Gagné; B. Stecklum; M. A. Kenworthy (2008). "The Lagoon Nebula and its Vicinity". In Bo Reipurth (ed.). Handbook of Star-Forming Regions: Volume 2 The Southern Sky. Astronomical Society of the Pacific. p. 53. ISBN 978-1-58381-671-4.

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