Anatomy of a Cosmic Seagull

Image: The Rosy Glow of a Cosmic Seagull. Colourful 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.

Credit: ESO/VPHAS+ team/N.J. Wright (Keele University)

ESO’s VST captures a celestial gull in flight

Colourful and wispy, this intriguing collection of objects is known as the Seagull Nebula, named for its resemblance to a gull in flight. Made up of dust, hydrogen, helium and traces of heavier elements, this region is the hot and energetic birthplace of new stars. The remarkable detail captured here by ESO’s VLT Survey Telescope (VST) reveals the individual astronomical objects that make up the celestial bird, as well as the finer features within them. The VST is one of the largest survey telescopes in the world observing the sky in visible light.


SulutPos.com, Garching bei München, Germany – The main components of the Seagull are three large clouds of gas, the most distinctive being Sharpless 2-296, 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.

The Seagull Nebula on the borders of the constellations of Monoceros and Canis Major. This chart shows the location of the head of the Seagull Nebula (red circle) in the constellation of Monoceros (The Unicorn) and not far from the brightest star in the sky, Sirius. This star-forming region is part of the larger Seagull Nebula (IC 2177), which sprawls across the border into the neighbouring Canis Major (The Great Dog). By coincidence this object lies very close in the sky to the location of the Thor’s Helmet Nebula (NGC 2359, marked with an orange circle and the ESO 50 logo). This unusual object was the winner of the Choose what the VLT Observes contest (ann12060). Credit: ESO, IAU and Sky & Telescope
The Seagull Nebula on the borders of the constellations of Monoceros and Canis Major. This chart shows the location of the head of the Seagull Nebula (red circle) in the constellation of Monoceros (The Unicorn) and not far from the brightest star in the sky, Sirius. This star-forming region is part of the larger Seagull Nebula (IC 2177), which sprawls across the border into the neighbouring Canis Major (The Great Dog).
By coincidence this object lies very close in the sky to the location of the Thor’s Helmet Nebula (NGC 2359, marked with an orange circle and the ESO 50 logo). This unusual object was the winner of the Choose what the VLT Observes contest (ann12060).
Credit: ESO, IAU and Sky & Telescope

It is the radiation emanating from these young stars that gives the clouds their fantastical colours and makes them so eye-catching, by ionising 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 ionised 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 cubic centimetre, 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 cubic centimetre.

Wide-field view of the entire Seagull Nebula (IC 2177). This wide-field view captures the evocative and colourful star formation region of the Seagull Nebula, IC 2177, on the borders of the constellations of Monoceros (The Unicorn) and Canis Major (The Great Dog). This view was created from images forming part of the Digitized Sky Survey 2. Credit: ESO/Digitized Sky Survey 2. Acknowledgement: Davide De Martin
Wide-field view of the entire Seagull Nebula (IC 2177). This wide-field view captures the evocative and colourful star formation region of the Seagull Nebula, IC 2177, on the borders of the constellations of Monoceros (The Unicorn) and Canis Major (The Great Dog). This view was created from images forming part of the Digitized Sky Survey 2.
Credit: ESO/Digitized Sky Survey 2. Acknowledgement: Davide De Martin

The Seagull lies along the border between the constellations of Canis Major (The Great Dog) and Monoceros (The Unicorn), at a distance of about 3700 light-years in one arm of the Milky WaySpiral galaxies can contain thousands of these clouds, almost all of which are concentrated along their whirling arms.

Several smaller clouds are also counted as part of the Seagull Nebula, including Sh2-297, which is a small, knotty addition to the tip of the gull’s upper “wing”, Sh2-292 and Sh2-295. These objects are all included in the Sharpless Catalogue, a list of over 300 clouds of glowing gas compiled by American astronomer Stewart Sharpless.

This image was taken using the VLT Survey Telescope (VST), one of the largest survey telescopes in the world observing the sky in visible light. The VST is designed to photograph large areas of the sky quickly and deeply.

Can you spot the seagull in this photo? We challenge our readers to let their imagination run free and outline the bird in our photo as they see it. Share your photos with the outline of the bird using the hashtag #SpotTheSeagull.

ESOcast 205 Light: The Rosy Glow of a Cosmic Seagull

 

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ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It has 16 Member States: Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Ireland, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile and with Australia as a Strategic Partner. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research.

ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope and its world-leading Very Large Telescope Interferometer as well as two survey telescopes, VISTA working in the infrared and the visible-light VLT Survey Telescope. Also at Paranal ESO will host and operate the Cherenkov Telescope Array South, the world’s largest and most sensitive gamma-ray observatory. ESO is also a major partner in two facilities on Chajnantor, APEX and ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre Extremely Large Telescope, the ELT, which will become “the world’s biggest eye on the sky”.

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