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IC5146 - Cocoon
M5 - NGC5904
M8 - Lagoon Nebula
M16 - Eagle Nebula
M20 - Trifid
M27 - Dumbbell
M31 - Andromeda
M33 - Pinwheel
M42 - Orion
M45 - The Pleiades
M51 - Whirlpool
M57 - Ring
M63 - Sunflower
M64 - Black-Eye
M65 - NGC3623
M67 - NGC2682
M98 - NGC4192
M99 - Pinwheel
M100 - NGC4321
M101 - NGC5457
M104 - Sombrero
M105 - NGC3379
M106 - NGC4258
C/2004 Q2 - Machholz
NGC 891
NGC2024 - Flame
NGC2244 - Rosette
NGC6960 - Veil
The Mice - NGC4676


Starforming Nebula M20 (NGC 6514), an emission and reflection nebula, with Open Star Cluster, in Sagittarius

Trifid Nebula



Discovered by Charles Messier in 1764.

The Trifid Nebula Messier 20 (M20, NGC 6514) in Sagittarius is a remarkable and beautiful object as it consists of both a conspicuous emission nebula and a remarkable reflection nebula component.

Charles Messier discovered this object on June 5, 1764, and described it as a cluster of stars of 8th to 9th magnitude, enveloped in nebulosity, where the remark on nebulosity follows only after the description of nearby M21, and includes that object.

The Trifid Nebula M20 is famous for its three-lobed appearance. This may have caused William Herschel, who normally carefully avoided to number Messier's objects in his catalog, to assign four different numbers to parts of this nebula: H IV.41 (cataloged May 26, 1786) and H V.10, H V.11, H V.12 (dated July 12, 1784). That he numbered this object at all may have its reason in the fact that Messier merely described it as 'Cluster of Stars.' The name 'Trifid' was first used by John Herschel to describe this nebula; this astronomer assigned only one catalog entry to the whole object (h 1991, h 3718, GC 4355) which became J.L.E. Dreyer's NGC 6514.

The dark nebula, which is the reason for the Trifid's appearance, was cataloged by Barnard as Barnard 85 (B 85).

The red emission nebula with its young star cluster near its center is surrounded by a blue reflection nebula which is particularly conspicuous to the northern end. The nebula's distance is rather uncertain, with values between 2,200 light years (Mallas/Kreimer; Glyn Jones has 2,300) and about 7,600 light years (C.R. O'Dell 1963). The Sky Catalog 2000 gives 5,200 light years, a value which is also used by Archinal and Hynes (2003), and which we adopt here. The WEBDA database has 3140, the Hubble Press Release of Jeff Hester (STScI-PRC99-42) gives "about 9000" light years.

As often for nebulae, magnitude estimates spread widely: Kenneth Glyn Jones gives 9.0, while Machholz has estimated 6.8 mag. This may partly come from the fact that the exciting star, HD 196692 or HN 40 or ADS 10991, is a triple system of 7th integrated magnitude (with components A: 7.6, B: 10.7, C: 8.7 mag). All are extremely hot; component A is of spectral type O5 to O7. The Sky Catalogue 2000.0 even lists 4 more, faint components of this "multiple star:" D: 10.7, E: 12.6, F: 14.0, and G: 13.4 mag. This star is located on the west side of the Trifid Nebula cluster. Situated on the northern edge is HD 164514 of visual magnitude 7.42, a supergiant of spectral type A5 Ia. The presence of these considerably bright stars makes brightness estimates for the nebula difficult.

In the sky, the Trifid nebula M20 is situated roughly 2 degrees northwest of the larger Lagoon Nebula M8, so that both nebulae form a nice target for wide field photographs, as these images of the M8 and M20 region, or the big DSSM image of this region. It is even closer to the open cluster M21 and shows up in the upper left edge of our M21 image.

(Credits to SEDS - Students for the Exploration and Development of Space)


Observer´s Log

Object name: M 20
Magnitude: 30,0
Size: 20,0 x 20,0
Object type: Open Cluster
Source catalog: Messier Catalog
Number: 20
Other ID: NGC6514
Type: C
Catalog number: 6514
Celestial type: 11
NGC/IC: 6514



M20 - Trifid Nebula


Number of Frames: 11

Exposure:  300s ISO 1600

Equipment: Takahashi FS-102NS, f/8, Canon EOS300D camera in prime focus

Date: 05-10-02

Reduced, aligned and stacked with ImagesPlus; final processing with Photoshop CS



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This site was last updated 2019-02-10                                                                                                                 Site created and maintained by Jorge Lázaro