VST captures three-in-one

Two of the sky’s more famous residents share the stage
with a lesser-known neighbour in this enormous three gigapixel
image from ESO’s VLT Survey Telescope (VST). On the right lies
the faint, glowing cloud of gas called Sharpless 2-54, the
iconic Eagle Nebula (Messier 16) is in the centre, and the
Omega Nebula (Messier 17) to the left. This cosmic trio makes
up just a portion of a vast complex of gas and dust within
which new stars are springing to life and illuminating their
surroundings. Credit: ESO

Two of the sky’s more famous residents share the stage with a
lesser-known neighbour in this enormous new three gigapixel
image from ESO’s VLT Survey Telescope (VST). On the right
lies Sharpless 2-54, the iconic Eagle Nebula is in the
centre, and the Omega Nebula to the left. This cosmic trio
makes up just a portion of a vast complex of gas and dust
within which new stars are springing to life and illuminating
their surroundings.

Sharpless 2-54 and the Eagle and Omega Nebula e are located
roughly 7000 light-years away—the first two fall within the
constellation of Serpens , while the latter lies within
Sagittarius. This region of the Milky Way houses a huge cloud
of star-making material. The three [nebulae] – indicate where
regions of this cloud have clumped together and collapsed to
form ; the energetic light from these
stellar newborns has caused ambient gas to emit light of its
own, which takes on the pinkish hue characteristic of areas
rich in hydrogen.

Two of the objects in this image were discovered in a similar
way. Astronomers first spotted bright star clusters in both
Sharpless 2-54 and the Eagle Nebula, later identifying the
vast, comparatively faint gas clouds swaddling the clusters. In
the case of Sharpless 2-54, British astronomer William Herschel
initially noticed its beaming star cluster in 1784. That
cluster, catalogued as NGC 6604, appears in this image on the
object’s left side. The associated very dim gas cloud remained
unknown until the 1950s, when American astronomer Stewart
Sharpless spotted it on photographs from the National
Geographic-Palomar Sky Atlas.

The Eagle Nebula did not have to wait so long for its full
glory to be appreciated. Swiss astronomer Philippe Loys de
Chéseaux first discovered its bright , NGC 6611, in 1745 or 1746. A couple
of decades later, French astronomer Charles Messier observed
this patch of sky and also documented the nebulosity present
there, recording the object as Messier 16 in his influential
catalogue.

As for the Omega Nebula, de Chéseaux did manage to observe its
more prominent glow and duly noted it as a in 1745. However, because the Swiss
astronomer’s catalogue never achieved wider renown, Messier’s
re-discovery of the Omega Nebula in 1764 led to its becoming
Messier 17, the seventeenth object in the Frenchman’s popular
compendium.

The observations from which this image was created were taken
with ESO’s VLT Survey Telescope (VST), located at ESO’s Paranal
Observatory in Chile. The huge final colour image was created
by mosaicing dozens of pictures—each of 256 megapixels—from the
telescope’s large-format OmegaCAM camera. The final result,
which needed lengthy processing, totals 3.3 gigapixels, one of
the largest images ever released by ESO.

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