Starship Asterisk*

ESA/Hubble wrote:

The magnificent central bar of NGC 2217 (also known as AM 0619-271) shines bright in the constellation of Canis Major (The Greater Dog), in this new image taken by the NASA/ESA Hubble Space Telescope. Roughly 65 million light-years from Earth, this barred spiral galaxy is a similar size to our Milky Way at 100 thousand light-years across. Many stars are concentrated in its central region forming the luminous bar, surrounded by a set of tightly wound spiral arms.

The central bar in these types of galaxies plays an important role in their evolution, helping to funnel gas from the disc into the middle of the galaxy. The transported gas and dust are then either formed into new stars or fed to the supermassive black hole at the galaxy's centre.

Image Credit: ESA/Hubble & NASA, D. Rosario

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This unusual lenticular galaxy, known as NGC 1947, has lost almost all the gas and dust from its signature spiral arms, which used to orbit around its centre. Discovered almost 200 years ago by James Dunlop, a Scottish-born astronomer who later studied the sky from Australia, NGC 1947 can only be seen from the southern hemisphere, in the constellation Dorado (The Dolphinfish).

Residing around 40 million light-years away from Earth, this galaxy shows off its structure by backlighting its remaining faint gas and dust disc with millions of stars. In this picture, taken with the NASA/ESA Hubble Space Telescope, the faint remnants of the galaxy’s spiral arms can still be made out in the stretched thin threads of dark gas encircling it. Without most of its star-forming material, it is unlikely that many new stars will be born within NGC 1947, leaving this galaxy to continue fading with time.

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.

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.