One galaxy, three supernovae: In astronomy, the devil is in the details — as this image, taken by the NASA/ESA Hubble Space Telescope’s Advanced Camera for Surveys and Wide-Field Camera 3, demonstrates. The numerous fuzzy blobs and glowing shapes scattered across this image make up a galaxy cluster named RXC J0949.8+1707. Located to the upper right of the frame sits an especially beautiful and interesting barred spiral galaxy, seen face-on. In the past decade, astronomers peering at this galaxy have possibly discovered not one but three examples of a cosmic phenomenon known as a supernova, the magnificently bright explosion of a star nearing the end of its life. The newest supernova candidate is nicknamed SN Antikythera, and can be seen to the lower right  of the host galaxy. This shone brightly in visible and infrared light over a number of years before fading slightly. The two other supernovae, nicknamed SN Eleanor and SN Alexander, were present in data collected in 2011 but are not visible in this image, which was taken a few years later — their temporary nature unambiguously confirmed their status as supernovae. If future observations of RXC J0949.8+1707 show SN Antikythera to have disappeared then we can most likely label it a supernova, as with its two older (and now absent from the images) siblings. This image was taken as part of an observing programme called RELICS (Reionization Lensing Cluster Survey). RELICS imaged 41 massive galaxy clusters with the aim of finding the brightest distant galaxies for the forthcoming NASA/ESA/CSA James Webb Space Telescope (JWST) to study.

Name: RXC J0949.8+1707
Type: Early Universe : Star : Evolutionary Stage : SupernovaEarly Universe : Galaxy : Grouping : Cluster
Category: Galaxies
Constellation: Leo
Release date: 18 June 2018, 06:00
Credit: ESA/Hubble & NASA, RELICS

An aging beauty: This rich and dense smattering of stars is a massive globular cluster, a gravitationally-bound collection of stars that orbits the Milky Way. Globular clusters are denser and more spherical than open star clusters like the famous Pleiades. They typically contain hundreds of thousands of stars that are thought to have formed at roughly the same time. Studies have shown that this globular cluster, named NGC 6139, is home to an aging population of stars. Most globular clusters orbiting the Milky Way are estimated to be over 10 billion years old; as a result they contain some of the oldest stars in our galaxy, formed very early in the galaxy’s history. However, their role in galactic evolution is still a matter of study. This cluster is seen roughly in the direction of the centre of the Milky Way, in the constellation of Scorpius (The Scorpion). This constellation is a goldmine of fascinating astronomical objects. Hubble has set its sights on Scorpius many times to observe objects such as the butterfly-like Bug Nebula, surprising binary star systems, and other dazzling globular clusters.

Name: NGC 6139
Type: Milky Way : Star : Grouping : Cluster : Globular
Category: Star Clusters
Constellation: Scorpius
Distance: 35000 light years
Release date: 25 June 2018, 06:00
Credit: ESA/Hubble & NASA

Zooming in on the early Universe: This busy image is a treasure trove of wonders. Bright stars from the Milky Way sparkle in the foreground, the magnificent swirls of several spiral galaxies are visible across the frame, and a glowing assortment of objects at the centre make up a massive galaxy cluster. Such clusters are the biggest objects in the Universe that are held together by gravity, and can contain thousands of galaxies of all shapes and sizes. Typically, they have a mass of about  one million billion times the mass of the Sun — unimaginably huge! Their incredible mass makes clusters very useful natural tools to test theories in astronomy, such as Einstein’s theory of general relativity. This tells us that objects with mass warp the fabric of spacetime around them; the more massive the object, the greater the distortion. An enormous galaxy cluster like this one therefore has a huge influence on the spacetime around it, even distorting the light from more distant galaxies to change a galaxy’s apparent shape, creating multiple images, and amplifying the galaxy’s light — a phenomenon called gravitational lensing. This image was taken by Hubble’s Advanced Camera for Surveys and Wide-Field Camera 3 as part of an observing programme called RELICS (Reionization Lensing Cluster Survey). RELICS imaged 41 massive galaxy clusters with the aim of finding the brightest distant galaxies for the forthcoming NASA/ESA/CSA James Webb Space Telescope (JWST) to study.

Name: RXC J2211.7-0350
Type: Early Universe : Galaxy : Grouping : ClusterEarly Universe : Cosmology : Phenomenon : Lensing
Category: Galaxies
Constellation: Aquarius
Distance: z=0.27 (redshift)
Release date: 2 July 2018, 06:00
Credit: ESA/Hubble & NASA, RELICS

A failed supernova?: Glowing warmly against the dark backdrop of the Universe, this image from the NASA/ESA Hubble Space Telescope shows an irregular galaxy called UGC 12682. Located approximately 70 million light-years away in the constellation of Pegasus (The Winged Horse), UGC 12682 is distorted and oddly-structured, with bright pockets of star formation. In November 2008, 14-year-old Caroline Moore from New York discovered a supernova in UGC 12682. This made her the youngest person at the time to have discovered a supernova. Follow-up observations by professional astronomers of the so-called SN 2008ha showed that it was peculiarly interesting in many  different ways: its host galaxy UGC 12682 rarely produces supernovae. It is one of the faintest supernovae ever observed and after the explosion it expanded very slowly, suggesting that the explosion did not release copious amounts of energy as usually expected. Astronomers have now classified SN 2008ha as a subclass of a Type Ia supernova, which is the explosion of a white dwarf that hungrily accretes matter from a companion star. SN 2008ha may have been the result of a partially failed supernova, explaining why the explosion failed to decimate the whole star.

Name: UGC 12682
Type: Local Universe : Star : Type : Variable : Irregular
Category: Galaxies
Constellation: Pegasus
Distance: 70 million light years
Release date: 9 July 2018, 06:00
Credit: ESA/Hubble & NASA