The VLT Survey Telescope (VST), a large telescope at ESO’s Paranal Observatory, has taken a brilliant picture of the Seagull Nebula, which lies along the border between the constellations of Canis Major and Monoceros, at a distance of 3,700 light-years.
Colorful and wispy Sharpless 2-296 forms the ‘wings ‘ of an area of sky known as the Seagull Nebula — named for its resemblance to a gull in flight. This celestial bird contains a fascinating mix of intriguing astronomical objects. Glowing clouds weave amid dark dust lanes and bright stars. The Seagull Nebula — made up of dust, hydrogen, helium and traces of heavier elements — is the hot and energetic birthplace of new stars. Image credit: ESO / VPHAS+ Team / N.J. Wright, Keele University.
Seagull Nebula’s main components are three large clouds of gas, the most distinctive being Sharpless 2-296 (Sh2-296), which forms the ‘wings.’
Spanning about 100 light-years from one wingtip to the other, Sh2-296 displays glowing material and dark dust lanes weaving amid bright stars. It is a beautiful example of an emission nebula, in this case an HII region, indicating active formation of new stars, which can be seen peppering this image.
It is the radiation emanating from these young stars that gives the clouds their fantastical colors and makes them so eye-catching, by ionizing the surrounding gas and causing it to glow. This radiation is also the main factor that determines the clouds’ shapes, by exerting pressure on the surrounding material and sculpting it into the whimsical morphologies we see.
Since each nebula has a unique distribution of stars and may, like this one, be a composite of multiple clouds, they come in a variety of shapes, firing astronomers’ imaginations and evoking comparisons to animals or familiar objects.
This diversity of shapes is exemplified by the contrast between Sh2-296 and Sh2-292.
The latter, seen here just below the ‘wings,’ is a more compact cloud that forms the seagull’s ‘head.’
Its most prominent feature is a huge, extremely luminous star called HD 53367 that is 20 times more massive than the Sun, and which we see as the seagull’s piercing ‘eye.’
Sh2-292 is both an emission nebula and a reflection nebula. Much of its light is emitted by ionized gas surrounding its nascent stars, but a significant amount is also reflected from stars outside it.
The dark swathes that interrupt the clouds’ homogeneity and give them texture are dust lanes — paths of much denser material that hide some of the luminous gas behind them.
Nebulae like this one have densities of a few hundred atoms per cm3, much less than the best artificial vacuums on Earth. Nonetheless, nebulae are still much denser than the gas outside them, which has an average density of about 1 atom per cm3.
