Starship Asterisk*

Image Credit: Petr Horálek/ESO

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This photograph, taken by ESO Photo Ambassador Petr Horálek, looks west from ESO’s Paranal Observatory in Chile.

The bright object at the centre of the frame is the Moon — slightly to its upper left is the ringed planet Saturn, while rocky Mercury sits to the lower left. Saturn and Mercury in conjunction can be difficult to see with the naked eye from some latitudes, but this breathtaking image captures them beautifully, despite the relatively bright light from the nearby Moon. The dusty Milky Way appears to split the sky horizontally, with a star-studded night view above and the last signs of the Sun lingering below. Many famous nebulae are visible across this cosmic curtain, such as the Lagoon Nebula, Cat’s Paw Nebula, and Trifid Nebula.

The individual telescopes in this image together make up ESO’s Very Large Telescope (VLT), the world’s most advanced optical and infrared observatory. The VLT consists of four large Unit Telescopes, each with a mirror 8.2 metres across, and four smaller Auxiliary Telescopes, with mirrors 1.8 metres in diameter.

Credit: ESA/Hubble & NASA, J. Lee; Acknowledgement: Leo Shatz

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An orange glow radiates from the centre of NGC 1792, the heart of this stellar forge. Captured by the NASA/ESA Hubble Space Telescope, this intimate view of NGC 1792 gives us some insight into this galactic powerhouse. The vast swathes of tell-tale blue seen throughout the galaxy indicate areas that are full of young, hot stars, and it is in the shades of orange, seen nearer the centre, that the older, cooler stars reside.

Nestled in the constellation of Columba (The Dove), NGC 1792 is both a spiral galaxy, and a starburst galaxy. Within starburst galaxies, stars are forming at comparatively exorbitant rates. The rate of star formation can be more than 10 times faster in a starburst galaxy than in the Milky Way. When galaxies have a large resevoir of gas, like NGC 1792, these short lived starburst phases can be sparked by galactic events such as mergers and tidal interactions. One might think that these starburst galaxies would easily consume all of their gas in a large forming event. However, supernova explosions and intense stellar winds produced in these powerful starbursts can inject energy into the gas and disperse it. This halts the star formation before it can completely deplete the galaxy of all its fuel. Scientists are actively working to understand this complex interplay between the dynamics that drive and quench these fierce bursts of star formation.

Image Credit: Yuri Beletsky (LCO)/ESO

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The antennas comprising the Atacama Large Millimeter/submillimeter Array (ALMA), in which ESO is a partner, appear to emit an eerie, vivid shade of green light in this Picture of the Week. Situated high up on the isolated Chajnantor plateau in Chile’s Atacama Desert, ALMA seems like the perfect place for friendly extraterrestrials to discreetly land and make contact…but something far more mundane is responsible for this otherworldly green glow. The light emanates from indicator lights, which show whether or not it is safe for staff to approach the antennas. A green light as pictured indicates that it’s safe to approach.

An alien world is, however, visible above the antennas. In the top left of the image, in the clear Chilean sky, two bright stars can be seen next to each other within the band of the Milky Way. These stars are often called The Pointers, as they “point” towards the bright diamond of the Southern Cross (Crux) just to their right. The one nearest to the Southern Cross is Beta Centauri, located some 400 light-years away, and the more distant star is Alpha Centauri, the closest star system to the Sun at a distance of only 4.37 light-years. This system contains the red dwarf star Proxima Centauri; in 2016, astronomers used ESO telescopes to find evidence of an Earth-sized planet orbiting Proxima Centauri in the habitable zone.

Image Credit: ESA/Hubble & NASA, S. Jha

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The narrow galaxy elegantly curving around its spherical companion in this image is a fantastic example of a truly strange and very rare phenomenon. This image, taken with the NASA/ESA Hubble Space Telescope, depicts GAL-CLUS-022058s, located in the southern hemisphere constellation of Fornax (The Furnace). GAL-CLUS-022058s is the largest and one of the most complete Einstein rings ever discovered in our Universe. The object has been nicknamed by the Principal Investigator and his team who are studying this Einstein ring as the "Molten Ring", which alludes to its appearance and host constellation.

First theorised to exist by Einstein in his general theory of relativity, this object’s unusual shape can be explained by a process called gravitational lensing, which causes light shining from far away to be bent and pulled by the gravity of an object between its source and the observer. In this case, the light from the background galaxy has been distorted into the curve we see by the gravity of the galaxy cluster sitting in front of it. The near exact alignment of the background galaxy with the central elliptical galaxy of the cluster, seen in the middle of this image, has warped and magnified the image of the background galaxy around itself into an almost perfect ring. The gravity from other galaxies in the cluster is soon to cause additional distortions.

Objects like these are the ideal laboratory in which to research galaxies too faint and distant to otherwise see.