Picture of the Week 2016

26 December 2016: This galaxy has a far more exciting and futuristic classification than most — it is a megamaser. Megamasers are intensely bright, around 100 million times brighter than the masers found in galaxies like the Milky Way. The entire galaxy essentially acts as an astronomical laser that beams out microwave emission rather than visible light (hence the ‘m’ replacing the ‘l’). This megamaser is named IRAS 16399-0937, and is located over 370 million light-years from Earth. This NASA/ESA Hubble Space Telescope image belies the galaxy’s energetic nature, instead painting it as a beautiful and serene cosmic rosebud. The image comprises observations captured across various wavelengths by two of Hubble’s instruments: the Advanced Camera for Surveys (ACS), and the Near Infrared Camera and Multi-Object Spectrometer (NICMOS). NICMOS’s superb sensitivity, resolution, and field of view gave astronomers the unique opportunity to observe the structure of IRAS 16399-0937 in detail. They found that IRAS …

19 December 2016: On a clear evening in April of 1789, the renowned astronomer William Herschel continued his unrelenting survey of the night sky, hunting for new cosmic objects — and found cause to celebrate! Lengthening his impressive list of cosmic discoveries yet again, the astronomer spotted this bright spiral galaxy, named NGC 4707, lurking in the constellation of Canes Venatici (The Hunting Dog). NGC 4707 lies roughly 22 million light-years from Earth. Over two centuries later, the NASA/ESA Hubble Space Telescope is able to view the same galaxy in far greater detail than Herschel could, allowing us to appreciate the intricacies and characteristics of NGC 4707 as never before. This striking image comprises observations from Hubble’s Advanced Camera for Surveys (ACS), one of a handful of high-resolution instruments currently aboard the space telescope. Herschel himself reportedly described NGC 4707 as a “small, stellar” galaxy; while it is classified as a spiral (type …

12 December 2016: In 1900, astronomer Joseph Lunt made a discovery: Peering through a telescope at Cape Town Observatory, the British–South African scientist spotted this beautiful sight in the southern constellation of Grus (The Crane): a barred spiral galaxy now named IC 5201. Over a century later, the galaxy is still of interest to astronomers. For this image, the NASA/ESA Hubble Space Telescope used its Advanced Camera for Surveys (ACS) to produce a beautiful and intricate image of the galaxy. Hubble’s ACS can resolve individual stars within other galaxies, making it an invaluable tool to explore how various populations of stars have sprung to life, evolved, and died throughout the cosmos. IC 5201 sits over 40 million light-years away from us. As with two thirds of all the spirals we see in the Universe — including the Milky Way, the galaxy has a bar of stars slicing through its centre.

5 December 2016: The constellation of Virgo (The Virgin) is especially rich in galaxies, due in part to the presence of a massive and gravitationally-bound collection of over 1300 galaxies called the Virgo Cluster. One particular member of this cosmic community, NGC 4388, is captured in this image, as seen by the NASA/ESA Hubble Space Telescope’s Wide Field Camera 3 (WFC3). Located some 60 million light-years away, NGC 4388 is experiencing some of the less desirable effects that come with belonging to such a massive galaxy cluster. It is undergoing a transformation, and has taken on a somewhat confused identity. While the galaxy’s outskirts appear smooth and featureless, a classic feature of an elliptical galaxy, its centre displays remarkable dust lanes constrained within two symmetric spiral arms, which emerge from the galaxy’s glowing core — one of the obvious features of a spiral galaxy. Within the arms, speckles of bright blue mark the …

28 November 2016: This delicate blue group of stars — actually an irregular galaxy named IC 3583 — sits some 30 million light-years away in the constellation of Virgo (The Virgin). It may seem to have no discernable structure, but IC 3583 has been found to have a bar of stars running through its centre. These structures are common throughout the Universe, and are found within the majority of spiral, many irregular, and some lenticular galaxies. Two of our closest cosmic neighbours, the Large and Small Magellanic Clouds, are barred, indicating that they may have once been barred spiral galaxies that were disrupted or torn apart by the gravitational pull of the Milky Way. Something similar might be happening with IC 3583. This small galaxy is thought to be gravitationally interacting with one of its neighbours, the spiral Messier 90. Together, the duo form a pairing known as Arp 76. It’s still unclear …

21 November 2016: This image of the spiral galaxy NGC 3274 comes courtesy of the NASA/ESA Hubble Space Telescope’s Wide Field Camera 3 (WFC3). Hubble’s WFC3 vision spreads from the ultraviolet light through to the near infrared , allowing astronomers to study a wide range of targets, from nearby star formation through to galaxies in the most remote regions of the cosmos. This particular image combines observations gathered in five different filters, bringing together ultraviolet, visible, and infrared light to show off NGC 3274 in all its glory. As with all of the data Hubble sends back to Earth, it takes advantage of the telescope’s location in space above our planet’s distorting atmosphere. WFC3 returns clear, crisp, and detailed images time after time. NGC 3274 is a relatively faint galaxy located over 20 million light-years away in the constellation of Leo (The Lion). The galaxy was discovered by Wilhelm Herschel in 1783. The …

14 November 2016: This Hubble image shows NGC 4789A, a dwarf irregular galaxy in the constellation of Coma Berenices. It certainly lives up to its name — the stars that call this galaxy home are smeared out across the sky in an apparently disorderly and irregular jumble, giving NGC 4789A a far more subtle and abstract appearance than its glitzy spiral and elliptical cousins. These stars may look as if they have been randomly sprinkled on the sky, but they are all held together by gravity. The colours in this image have been deliberately exaggerated to emphasise the mix of blue and red stars. The blue stars are bright, hot and massive stars that have formed relatively recently, whereas the red stars are much older. The presence of both tells us that stars have been forming in this galaxy throughout its history. At a distance of just over 14 million light-years away NGC …

7 November 2016: NGC 1222, seen in this image taken with the Wide Field Camera 3 on board the NASA/ESA Hubble Space Telescope (HST), is a galaxy with a rather eventful story to tell. NGC 1222 has been described as a peculiar example of a type of galaxy known as a lenticular galaxy. Typically, this kind of galaxy would present a rather smooth appearance on the sky and would consist mostly of old, reddish stars. A bit dull, perhaps. But NGC 1222 is certainly not a typical member of its class — and it’s anything but dull. Observations show the characteristic features of very recent star formation on a huge scale — an event known as a starburst. The reason for all this violent activity is caused by the fact that NGC 1222 is not alone. It actually contains three compact regions, each of which appears to be the central nucleus of a …

31 October 2016: In 1054 AD, during the Song dynasty, Chinese astronomers spotted a bright new star in the night sky. This newcomer turned out to be a violent explosion within the Milky Way, caused by the spectacular death of a star some 1600 light-years away. This explosion created one of the most well-studied and beautiful objects in the night sky — the Crab Nebula. The beautiful result of this cataclysmic Type II supernova is shown here, imaged by the NASA/ESA Hubble Space Telescope’s Advanced Camera for Surveys. Unlike more commonly seen views of this remnant (heic0515), which show incredibly intricate branches and spires laced throughout the region, this image uses just a single filter, giving rise to a smoother and far simpler view of the famous nebula. The unstoppable collapse of the Crab’s progenitor star led to the formation of a rapidly rotating neutron star named the Crab Pulsar, which lurks at …

24 October 2016: Globular clusters offer some of the most spectacular sights in the night sky. These ornate spheres contain hundreds of thousands of stars, and reside in the outskirts of galaxies. The Milky Way contains over 150 such clusters — and the one shown in this NASA/ESA Hubble Space Telescope image, named NGC 362, is one of the more unusual ones. As stars make their way through life they fuse elements together in their cores, creating heavier and heavier elements — known in astronomy as metals — in the process. When these stars die, they flood their surroundings with the material they have formed during their lifetimes, enriching the interstellar medium with metals. Stars that form later therefore contain higher proportions of metals than their older relatives. By studying the different elements present within individual stars in NGC 362, astronomers discovered that the cluster boasts a surprisingly high metal content, indicating that …

17 October 2016: It may be famous for hosting spectacular sights such as the Tucana Dwarf Galaxy and 47 Tucanae (heic1510), the second brightest globular cluster in the night sky, but the southern constellation of Tucana (The Toucan) also possesses a variety of unsung cosmic beauties. One such beauty is NGC 299, an open star cluster located within the Small Magellanic Cloud just under 200 000 light-years away. Open clusters such as this are collections of stars weakly bound by the shackles of gravity, all of which formed from the same massive molecular cloud of gas and dust. Because of this, all the stars have the same age and composition, but vary in their mass because they formed at different positions within the cloud. This unique property not only ensures a spectacular sight when viewed through a sophisticated instrument attached to a telescope such as Hubble’s Advanced Camera for Surveys, but gives astronomers …

10 October 2016: This image, taken by the NASA/ESA Hubble Space Telescope’s Wide Field Planetary Camera 2, shows a spiral galaxy named NGC 278. This cosmic beauty lies some 38 million light-years away in the northern constellation of Cassiopeia (The Seated Queen). While NGC 278 may look serene, it is anything but. The galaxy is currently undergoing an immense burst of star formation. This flurry of activity is shown by the unmistakable blue-hued knots speckling the galaxy’s spiral arms, each of which marks a clump of hot newborn stars. However, NGC 278’s star formation is somewhat unusual; it does not extend to the galaxy’s outer edges, but is only taking place within an inner ring some 6500 light-years across. This two-tiered structure is visible in this image — while the galaxy’s centre is bright, its extremities are much darker. This odd configuration is thought to have been caused by a merger with a …

3 October 2016: This Hubble image shows the central region of a spiral galaxy known as NGC 247. NGC 247 is a relatively small spiral galaxy in the southern constellation of Cetus (The Whale). Lying at a distance of around 11 million light-years from us, it forms part of the Sculptor Group, a loose collection of galaxies that also contains the more famous NGC 253 (otherwise known as the Sculptor Galaxy). NGC 247’s nucleus is visible here as a bright, whitish patch, surrounded by a mixture of stars, gas and dust. The dust forms dark patches and filaments that are silhouetted against the background of stars, while the gas has formed into bright knots known as H II regions, mostly scattered throughout the galaxy’s arms and outer areas. This galaxy displays one particularly unusual and mysterious feature — it is not visible in this image, but can be seen clearly in wider views …

26 September 2016: This shining disc of a spiral galaxy sits approximately 25 million light-years away from Earth in the constellation of Sculptor. Named NGC 24, the galaxy was discovered by British astronomer William Herschel in 1785, and measures some 40 000 light-years across. This picture was taken using the NASA/ESA Hubble Space Telescope’s Advanced Camera for Surveys, known as ACS for short. It shows NGC 24 in detail, highlighting the blue bursts (young stars), dark lanes (cosmic dust), and red bubbles (hydrogen gas) of material peppered throughout the galaxy’s spiral arms. Numerous distant galaxies can also been seen hovering around NGC 24’s perimeter. However, there may be more to this picture than first meets the eye. Astronomers suspect that spiral galaxies like NGC 24 and the Milky Way are surrounded by, and contained within, extended haloes of dark matter. Dark matter is a mysterious substance that cannot be seen; instead, it reveals …

19 September 2016: This intriguing new image captured with the NASA/ESA Hubble Space Telescope shows a dust-bathed cluster of fragments from a disintegrated comet. The comet in question, named 332P/Ikeya-Murakami, split into this shower of fragments in the closing months of 2015. Fragmenting comets such as 332P/Ikeya-Murakami have long been objects of fascination for astronomers worldwide. Famously, Comet Shoemaker-Levy 9 disintegrated in 1992, crashing into the atmosphere of Jupiter at nearly 200 000 kilometres per hour, creating scars on it almost half the size of Earth. Though well-studied, objects such as this remain a puzzle to astronomers; no theory fully explains why comets split apart on their long journeys around the Sun. Hubble will continue to observe 332P/Ikeya-Murakami and comets like it, unravelling the nature of these mysterious objects.

12 September 2016: A lone source shines out brightly from the dark expanse of deep space, glowing softly against a picturesque backdrop of distant stars and colourful galaxies. Captured by the NASA/ESA Hubble Space Telescope’s Advanced Camera for Surveys (ACS), this scene shows PGC 83677, a lenticular galaxy — a galaxy type that sits between the more familiar elliptical and spiral varieties in the Hubble sequence. This image was obtained as part of the Coma Cluster Survey. It reveals both the relatively calm outskirts and intriguing core of PGC 83677. Here, studies have uncovered signs of a monstrous black hole that is spewing out high-energy X-rays and ultraviolet light.

5 September 2016: This shot from the NASA/ESA Hubble Space Telescope shows a maelstrom of glowing gas and dark dust within one of the Milky Way’s satellite galaxies, the Large Magellanic Cloud (LMC). This stormy scene shows a stellar nursery known as N159, an HII region over 150 light-years across. N159 contains many hot young stars. These stars are emitting intense ultraviolet light, which causes nearby hydrogen gas to glow, and torrential stellar winds, which are carving out ridges, arcs, and filaments from the surrounding material. At the heart of this cosmic cloud lies the Papillon Nebula, a butterfly-shaped region of nebulosity. This small, dense object is classified as a High-Excitation Blob, and is thought to be tightly linked to the early stages of massive star formation. N159 is located over 160 000 light-years away. It resides just south of the Tarantula Nebula (heic1402), another massive star-forming complex within the LMC. It was …

29 August 2016: The closest star system to the Earth is the famous Alpha Centauri group. Located in the constellation of Centaurus (The Centaur), at a distance of 4.3 light-years, this system is made up of the binary formed by the stars Alpha Centauri A and Alpha Centauri B, plus the faint red dwarf Alpha Centauri C, also known as Proxima Centauri. The NASA/ESA Hubble Space Telescope has given us this stunning view of the bright Alpha Centauri A (on the left) and Alpha Centauri B (on the right), flashing like huge cosmic headlamps in the dark. The image was captured by the Wide Field and Planetary Camera 2 (WFPC2). WFPC2 was Hubble’s most used instrument for the first 13 years of the space telescope’s life, being replaced in 2009 by WFC3 during Servicing Mission 4. This portrait of Alpha Centauri was produced by observations carried out at optical and near-infrared wavelengths. Compared …

22 August 2016: This image, courtesy of the NASA/ESA Hubble Space Telescope’s Advanced Camera for Surveys (ACS), captures the glow of distant stars within NGC 5264, a dwarf galaxy located just over 15 million light-years away in the constellation of Hydra (The Sea Serpent). Dwarf galaxies like NGC 5264 typically possess around a billion stars — just one per cent of the number of stars found within the Milky Way. They are usually found orbiting other, larger, galaxies such as our own, and are thought to form from the material left over from the messy formation of their larger cosmic relatives. NGC 5264 clearly possesses an irregular shape — unlike the more common spiral or elliptical galaxies — with knots of blue star formation. Astronomers believe that this is due to the gravitational interactions between NGC 5264 and other galaxies nearby. These past flirtations sparked the formation of new generations of stars, which …

15 August 2016: Several thousand years ago, a star some 160 000 light-years away from us exploded, scattering stellar shrapnel across the sky. The aftermath of this energetic detonation is shown here in this striking image from the NASA/ESA Hubble Space Telescope’s Wide Field Camera 3. The exploding star was a white dwarf located in the Large Magellanic Cloud, one of our nearest neighbouring galaxies. Around 97% of stars within the Milky Way that are between a tenth and eight times the mass of the Sun are expected to end up as white dwarfs. These stars can face a number of different fates, one of which is to explode as supernovae, some of the brightest events ever observed in the Universe. If a white dwarf is part of a binary star system, it can siphon material from a close companion. After gobbling up more than it can handle — and swelling to approximately …