Multi-megapixel image brings open star cluster into sharp focus

2 pictures

ESO image containing a number of the bright young stars that make up the Messier 18 open star cluster(Credit: ESO)

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The European Southern Observatory (ESO) has released a colossal 615 megapixel visible light image of a stunning collection of bright young stars that make up the Messier 18 open cluster. By observing the cluster, which is located around 4,600 light-years from Earth in the constellation of Sagittarius, astronomers can test their understanding of how stars evolve, and eventually die, often giving rise to the next generation of stellar bodies.

Messier 18 forms part of the over 100 strong Messier catalog of astronomical objects that were discovered by 18th century astronomer Charles Messier as he scoured the night sky in search of undiscovered comets.

Also referred to as NGC 663, the hive of brightly colored stars contained in the image form part of a stellar group known as an open cluster. Over a thousand of these relatively loose star formations have already been discovered, which, having formed from the same cloud of interstellar gas, share exactly the same make up, and vary significantly only in terms of their masses.

The ability to observe large numbers of stars that sit at the same distance from Earth, and share so many characteristics, presents astronomers with a fantastic opportunity to observe the evolution and and death of stellar bodies such as our own Sun.

Wide-field view of the region surrounding Messier 18, with the cluster itself detectable as a collection of bright stars in the center of the image(Credit: ESO/Digitized Sky Survey 2. Acknowledgement: Davide De Martin)

It is believed that our Sun was created in an open cluster. Over time, the powerful stellar winds created by our young Sun and its siblings blasted away the surrounding clouds of leftover gas and dust, which in turn weakened the gravitational binding that held the stellar bodies together. The tumultuous gravitational influence of the surrounding stars could then have worked to eject our Sun, and others like it, dispersing the stars across our region of the Milky Way.

The newly-released image of Messier 18 was captured by the 2.6 m (8.5 ft) VLT Survey Telescope (VST) located at the ESO's Paranal Observatory in Chile. The VST is currently the largest operational telescope in the world designed to survey large areas of the sky in the visible light spectrum, boasting a field of view as broad as two full Moons. The cutting edge telescope is equipped with a 268 megapixel camera, and capable of imaging the cosmos in a wide range of wavelengths from ultraviolet through to near-infrared.

The 30,577 x 20,108 pixel beast of an image is characterized by clouds of glowing red gas peppered with bright, white and blue stars, along with the occasional dark filaments of cosmic dust that work to absorb the light emitted by cosmic wonders lurking behind.

The blue and white colors of the stars indicate that the cluster is a mere 30 million years old, which makes it an infant in the context of the other open clusters discovered scattered around the Milky Way. These young, powerful stars are responsible for the red glow of the surrounding gas, as the deluge of ultraviolet light thrown out by the super hot stars strips the clouds of the electrons, causing them to emit their own reddish light in the process.

The video below shows the cluster.

Source: ESO

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