he Lagoon Nebula Messier 8 (M8, NGC 6523) is one of the finest and brightest star-forming regions in the sky. It is a giant cloud of interstellar matter which is currently undergoing vivid star formation, and has already formed a considerable cluster of young stars.

One of the remarkable features of the Lagoon Nebula is the presence of dark nebulae known as 'globules' (Burnham) which are collapsing protostellar clouds with diameters of about 10,000 AU (Astronomical Units). Some of the more conspicuous globules have been cataloged in E.E. Barnard's catalog of dark nebulae: Barnard 88 (B 88), the comet-shaped globule extended North-to-South (up-down) in the right half and near top of the image, small B 89 in the region of cluster NGC 6530, and long, narrow black B 296 at the south edge of the nebula (lower edge of the image). According to David Eichler, the nebula has probably a depth comparable to its linear extension indicated above.

Within the brightest part of the Lagoon Nebula, a remarkable feature can be seen, which according to its shape is called the "Hourglass Nebula". This feature was discovered by John Herschel and occurs in a region where a vivid star formation process appears to take place currently; the bright emission is caused by heavy excitation of very hot, young stars, the illuminator of the hourglass is the hot star Herschel 36 (mag 9.5, spectral class O7). Closely by this feature is the apparently brightest of the stars associated with the Lagoon Nebula, 9 Sagittarii (mag 5.97, spectral class O5), which surely contributes a lot of the high energy radiation which excites the nebula to shine.

As published in January 1997, the Hubble Space Telescope has been used to study the Hourglass Nebula region in the Lagoon Nebula M8.

The young open cluster NGC 6530 associated with the Lagoon Nebula M8 was classified as of Trumpler type "II 2 m n" (see e.g. the Sky Catalog 2000), meaning that it is detached but only weakly concentrated toward its center, its stars scatter in a moderate range of brightness, it is moderately rich (50--100 stars), and associated with nebulosity (certainly, with the Lagoon nebula). As the light of its member stars show little reddening by interstellar matter, this cluster is probably situated just in front of the Lagoon Nebula. Its brightest star is a 6.9 mag hot O5 star, and Eichler gives its age as 2 million years. Woldemar G÷tz mentions this cluster as containing one peculiar Of star, an extremely hot bright star of spectral type O with peculiar spectral lines of ionized Helium and Nitrogen.

M8 is situated in a very conspicuous field of the Sagittarius Milky Way.


Technical Description:
Imaging telescope or lens: Skywatcher Esprit 120mm f/7
Imaging camera: Starlight Xpress Trius SX-694 mono
Mount: Sky-Watcher NEQ-6 Goto
Guiding camera: Starlight-XPress Loadstar guider
Software: PixInsight
Filters: Astronomik LRGB 36mm, Baader Planetarium Ha - OIII - SII
Accessories: SBIG OAG-8300, SBIG Filter Wheel FW8-8300
Resolution: 3204x2448
Dates: July 1, 2016
Frames: 48x1200"
Integration: 16.0 hours
Avg. Moon age: 25.69 days
Avg. Moon phase: 15.77%
Locations: Lily's Flower Observatory, Santa Rita do Sapucai, Minas Gerais, Brazil