Picture of the Week

22 March 2021: This week’s Hubble/ESA Picture of the Week features NGC 7678 — a galaxy located approximately 164 million light-years away in the constellation of Pegasus (The Winged Horse). With a diameter of around 115 000 light-years, this bright spiral galaxy is a similar size to our own galaxy (the Milky Way), and was discovered in 1784 by the German-British astronomer William Herschel. The Atlas of Peculiar Galaxies is a catalogue which was produced in 1966 by the American astronomer Halton Arp. NGC 7678 is among the 338 galaxies presented in this catalogue, which organises peculiar galaxies according to their unusual features. Catalogued here as Arp 28, this galaxy is listed together with six others in the group “spiral galaxies with one heavy arm”.

15 March 2021: Located around 5000 light-years away in the constellation of Cygnus (The Swan), Abell 78 is an unusual type of planetary nebula. After exhausting the nuclear fuel in their cores, stars with a mass of around 0.8 to 8 times the mass of our Sun collapse to form dense and hot white dwarf stars. As this process occurs, the dying star will throw off its outer layers of material, forming an elaborate cloud of gas and dust known as a planetary nebula. This phenomenon is not uncommon, and planetary nebulae are a popular focus for astrophotographers because of their often beautiful and complex shapes. However, a few like Abell 78 are the result of a so-called “born again” star. Although the core of the star has stopped burning hydrogen and helium, a thermonuclear runaway at its surface ejects material at high speeds. This ejecta shocks and sweeps up the material of …

8 March 2021: Nestled amongst the vast clouds of star-forming regions like this one lie potential clues about the formation of our own Solar System. This week’s NASA/ESA Hubble Space Telescope Picture of the Week features AFGL 5180, a beautiful stellar nursery located in the constellation of Gemini (The Twins). At the centre of the image, a massive star is forming and blasting cavities through the clouds with a pair of powerful jets, extending to the top right and bottom left of the image. Light from this star is mostly escaping and reaching us by illuminating these cavities, like a lighthouse piercing through the storm clouds. Stars are born in dusty environments and although this dust makes for spectacular images, it can prevent astronomers from seeing stars embedded in it. Hubble’s Wide Field Camera 3 (WFC3) instrument is designed to capture detailed images in both visible and infrared light, meaning that the young …

1 March 2021: NGC 2336 is the quintessential galaxy — big, beautiful and blue — and it is captured here by the NASA/ESA Hubble Space Telescope. The barred spiral galaxy stretches an immense 200 000 light-years across and is located approximately 100 million light years away in the northern constellation of Camelopardalis (The Giraffe). Its spiral arms are glittered with young stars, visible in their bright blue light. In contrast, the redder central part of the galaxy is dominated by older stars. NGC 2336 was discovered in 1876 by German astronomer Wilhelm Tempel, using a 28-centimetre telescope. This Hubble image is so much better than the view Tempel would have had — Hubble’s main mirror is 2.4 metres across, nearly ten times the size of the telescope Tempel used. In 1987, NGC 2336 experienced a Type-Ia supernova, the only observed supernova in the galaxy since its discovery 111 years earlier.

22 February 2021: This NASA/ESA Hubble Space Telescope Picture of the Week features NGC4826 — a spiral galaxy located 17 million light-years away in the constellation of Coma Berenices (Berenice’s Hair). This galaxy is often referred to as the “Black Eye”, or “Evil Eye”, galaxy because of the dark band of dust that sweeps across one side of its bright nucleus. NGC4826 is known by astronomers for its strange internal motion. The gas in the outer regions of this galaxy and the gas in its inner regions are rotating in opposite directions, which might be related to a recent merger. New stars are forming in the region where the counter rotating gases collide. This galaxy was first discovered in 1779 by the English astronomer Edward Pigott.

15 February 2021: Herbig-Haro objects are some of the rarer sights in the night sky, taking the form of thin spindly jets of matter floating amongst the surrounding gas and stars. The two Herbig-Haro objects catalogued as HH46 and HH47, seen in this image taken with the NASA/ESA Hubble Space Telescope, were spotted in the constellation of Vela (The Sails), at a distance of over 1400 light-years from Earth. Prior to its discovery in 1977 by the American astronomer R. D. Schwartz, the exact mechanism by which these multi-coloured objects formed was unknown. Before 1997 it was theorised by Schwartz and others that the objects could be a type of reflection nebula, or a type of shock wave formed from the gas emitted from a star interacting with the surrounding matter. The mystery was finally solved when a protostar, unseen in this image, was discovered at the centre of the long jets of …

8 February 2021: This week’s NASA/ESA Hubble Space Telescope Picture of the Week features an impressive portrait of M1-63, a beautifully captured example of a bipolar planetary nebula located in the constellation of Scutum (the Shield). A nebula like this one is formed when the star at its centre sheds huge quantities of material from its outer layers, leaving behind a spectacular cloud of gas and dust. It is believed that a binary system of stars at the centre of the bipolar nebula is capable of creating hourglass or butterfly-like shapes like the one in this image. This is because the material from the shedding star is funnelled towards its poles, with the help of the companion, creating the distinctive double-lobed structure seen in nebulae such as M1-63.

1 February 2021: A bright foreground star isn’t enough to distract from the grandeur of the galaxy UGC 3855, captured here by the NASA/ESA Hubble Space Telescope. While this foreground star is incredibly bright to Hubble’s eye, it does not outshine the details of the background galaxy. Many young blue stars are sprinkled throughout the circular patterns of UGC 3855’s arms, contrasted and complemented by dark lanes of dust also following the spiral structure. A glancing look at UGC 3855 may only leave you with an impression of the galaxy, but spare a moment longer and the intricacies of the galaxy begin to emerge. Located in the constellation of Lynx , UGC 3855 is a cosmic beauty to behold.

25 January 2021: The lives of planetary nebulae are often chaotic, from the death of their parent star to the scattering of its contents far out into space. Captured here by the NASA/ESA Hubble Space Telescope, ESO 455-10 is one such planetary nebula, located in the constellation of Scorpius (The Scorpion). The oblate shells of ESO 455-10, previously held tightly together as layers of its central star, not only give this planetary nebula its unique appearance, but also offer information about the nebula. Seen in a field of stars, the distinct asymmetrical arc of material over the north side of the nebula is a clear sign of interactions between ESO 455-10 and the interstellar medium. The interstellar medium is the material — consisting of matter and radiation — between star systems and galaxies. The star at the centre of ESO 455-10 allows Hubble to see the interaction with the gas and dust of …

18 January 2021: Located in the constellation of Virgo (The Virgin), around 50 million light-years from Earth, NGC 4535 is truly a stunning sight to behold. Despite the incredible quality of this image, taken from the NASA/ESA Hubble Space Telescope, NGC 4535 has a hazy, somewhat ghostly, appearance when viewed from a smaller telescope. This led amateur astronomer Leland S. Copeland to nickname NGC 4535 the “Lost Galaxy” in the 1950s. The bright colours in this image aren’t just beautiful to look at, as they actually tell us about the population of stars within this barred spiral galaxy. The bright blue-ish colours, seen nestled amongst NGC 4535’s long, spiral arms, indicate the presence of a greater number of younger and hotter stars. In contrast, the yellower tones of this galaxy’s bulge suggest that this central area is home to stars which are older and cooler. This galaxy was studied as part of the …

11 January 2021: First discovered in 1798 by German-English astronomer William Hershel, NGC 613 is a galaxy which lies in the southern constellation of Sculptor 67 million light-years away. Featured here in a new image from the NASA/ESA Hubble Space Telescope, NGC 613 is a lovely example of a barred spiral galaxy. It is easily distinguishable as such because of its well defined central bar and long arms, which spiral loosely around its nucleus. As revealed by surveys, about two thirds of spiral galaxies, including our own Milky Way galaxy, contain a bar. Recent studies have shown that bars are more common in galaxies now than they were in the past, which gives us important clues about galaxy formation and evolution.

4 January 2021: The galaxy NGC 6946 is nothing short of spectacular. In the last century alone, NGC 6946 has experienced 10 observed supernovae, earning its nickname as the Fireworks Galaxy. In comparison, our Milky Way averages just 1-2 supernova events per century. This NASA/ESA Hubble Space Telescope image shows the stars, spiral arms, and various stellar environments of NGC 6946 in phenomenal detail. We are able to marvel at NGC 6946 as it is a face-on galaxy, which means that we see the galaxy “facing” us, rather than seeing it from the side (known as edge-on). The Fireworks Galaxy is further classified as an intermediate spiral galaxy and as a starburst galaxy. The former means the structure of NGC 6946 sits between a full spiral and a barred spiral galaxy, with only a slight bar in its centre, and the latter means it has an exceptionally high rate of star formation. The …

23 December 2020: 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. Weighing from a few hundred to over a billion times the mass of our Sun, supermassive black holes are present in …

21 December 2020: 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.

14 December 2020: 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 …

7 December 2020: 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 …

30 November 2020: This large expanse of space captured with the Hubble Space Telescope features the galaxy SDSSJ225506.80+005839.9. Unlike many other extravagant galaxies and stunning nebulae imaged by Hubble, this galaxy does not have a short popular name, and is only known by its long SDSS name, which refers to its coordinates in the sky. This galaxy - visible in the center right portion of the image - and its many wondrous neighbouring galaxies lie in the constellation of Pisces (The Fish). This is a post-starburst galaxy, which is a product of galaxies that have merged within the past billion years. This merger event drove gas to the galaxy's center and created an abundance of new stars, of which the brightest are visible in the remnant galaxy's core. The visible shells and tails surrounding the galaxy are also a result of this merger event. Residing far beyond our own Milky Way, it is …

23 November 2020: Some of the most stunning views of our sky occur at sunset, when sunlight pierces the clouds, creating a mixture of bright and dark rays formed by the clouds’ shadows and the beams of light scattered by the atmosphere. Astronomers studying the nearby galaxy IC 5063 are tantalized by a similar effect in this new image from the NASA/ESA Hubble Space Telescope. In this case, a collection of narrow bright rays and dark shadows is seen beaming out of the blazingly bright center of the active galaxy, shooting across at least 36,000 light-years. Astronomers have traced the rays back to the galaxy’s core, the location of an active supermassive black hole. The black hole is feeding on infalling material, producing a powerful gusher of light from superheated gas near it. Although the researchers have developed several plausible theories for the lightshow, the most intriguing idea suggests that the shadows are …

16 November 2020: Observed with the NASA/ESA Hubble Space Telescope, the faint galaxy featured in this image is known as UGC 12588. Unlike many spiral galaxies, UGC 12588 displays neither a bar of stars across its centre nor the classic prominent spiral arm pattern. Instead, to a viewer, its circular, white and mostly unstructured centre makes this galaxy more reminiscent of a cinnamon bun than a mega-structure of stars and gas in space. Lying in the constellation of Andromeda in the Northern hemisphere, this galaxy is classified as a spiral galaxy. Unlike the classic image of a spiral galaxy, however, the huge arms of stars and gas in UGC 12588 are very faint, undistinguished, and tightly wound around its centre. The clearest view of the spiral arms comes from the bluer stars sprinkled around the edges of the galaxy that highlight the regions where new star formation is most likely taking place.

9 November 2020: This NASA/ESA Hubble Space Telescope image features the galaxy LRG-3-817, also known as SDSS J090122.37+181432.3. The galaxy, its image distorted by the effects of gravitational lensing, appears as a long arc to the left of the central galaxy cluster. Gravitational lensing occurs when a large distribution of matter, such as a galaxy cluster, sits between Earth and a distant light source. As space is warped by massive objects, the light from the distant object bends as it travels to us and we see a distorted image of it. This effect was first predicted by Einstein’s general theory of relativity. Strong gravitational lenses provide an opportunity for studying properties of distant galaxies, since Hubble can resolve details within the multiple arcs that are one of the main results of gravitational lensing. An important consequence of lensing distortion is magnification, allowing us to observe objects that would otherwise be too far away …