Interacting Galaxies Arp 107 as seen by Webb

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An interaction between an elliptical galaxy and a larger spiral galaxy, collectively known as Arp 107, seems to have given the spiral a happier outlook thanks to the two bright "eyes" and the wide semicircular "smile" that have resulted. This image is a composite, combining observations from Webb's MIRI (Mid-InfraRed Instrument) and NIRCam (Near-InfraRed Camera).

NIRCam highlights the stars within both galaxies and reveals the connection between them: a transparent, white bridge of stars pulled from both galaxies during their passage. MIRI data, represented in orange-red, show star-forming regions and dust that is composed of soot-like organic molecules known as polycyclic aromatic hydrocarbons. MIRI also provides a snapshot of the bright nucleus of the large spiral, home to a supermassive black hole.

The spiral galaxy is classified as a Seyfert galaxy, one of the two largest groups of active galaxies, along with galaxies that host quasars. Seyfert galaxies aren't as luminous or as distant as quasars, so they are better places to study similar phenomena in lower-energy light, like infrared.

This region is much like the Cartwheel Galaxy, one of the first interacting galaxies that Webb observed. Arp 107 may have turned out very similar in appearance to the Cartwheel, but since the smaller elliptical galaxy had an off-centre collision instead of a direct hit, the spiral galaxy got away with only its spiral arms being disturbed.

The collision isn't as bad as it sounds. Although there was much star formation occurring before, collisions between galaxies can compress gas, improving the conditions needed for more stars to form. On the other hand, as Webb reveals, collisions also disperse a lot of gas, potentially depriving new stars of the material they need to form.

Webb has captured these galaxies in the process of merging, which will take hundreds of millions of years. As the two galaxies rebuild after the chaos of their collision, Arp 107 may lose its smile, but it will inevitably turn into something just as interesting for future astronomers to study.

Arp 107 is located 465 million light-years from Earth in the constellation Leo Minor.

Image Credit: NASA, ESA, CSA, STScI

Image enhancement: Jean-Baptiste Faure

Seyfert Spiral Galaxy UGC 3478

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Looking past its long spiral arms filled with stars and the dark threads of dust crossing it, your eye might be caught by the shining point at the center of UGC 3478, the spiral galaxy starring in this Hubble picture. This point is the galaxy's nucleus, and indeed there is something special about it: it is a growing giant black hole which astronomers call an active galactic nucleus, or AGN.

UGC 3478, located in the constellation Camelopardalis, is what is known as a Seyfert galaxy. This is a type of galaxy with an AGN at its core. Like all such "active galaxies", the brightness that you see here hides a supermassive black hole at the center of the galaxy. A disc of gas spirals into this black hole, and as the material crashes together and heats up it emits very strong radiation. The spectrum of this radiation includes hard X-ray emission, which clearly mark it out from the stars in the galaxy. Despite the strong brightness of the compact central region, we can still clearly see the disc of the galaxy around it, which makes the galaxy a Seyfert galaxy.

Many active galaxies are known to astronomers at vast distances from Earth, thanks to the great brightness of their nuclei highlighting them next to other, dimmer galaxies. At 128 million light-years from Earth, UGC 3478 is positively neighbourly to us. The data used to make this image comes from a Hubble survey of nearby powerful AGNs found in relatively high-energy X-rays, like this one, which it is hoped can help astronomers to understand how the galaxies interact with the supermassive black holes at their hearts.

Image Credit: ESA/Hubble and NASA, M. Koss, A. Barth

Image enhancement: Jean-Baptiste Faure

Barred Spiral Galaxy NGC 3783

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This image features NGC 3783, a bright barred spiral galaxy about 130 million light-years from Earth, that also lends its name to the eponymous NGC 3783 galaxy group. Like galaxy clusters, galaxy groups are aggregates of gravitationally bound galaxies. Galaxy groups, however, are less massive and contain fewer members than galaxy clusters do: where galaxy clusters can contain hundreds or even thousands of constituent galaxies, galaxy groups do not typically include more than 50. The Milky Way is actually part of a galaxy group, known as the Local Group, which contains two other large galaxies (Andromeda and the Triangulum galaxy), as well as several dozen satellite and dwarf galaxies. The NGC 3783 galaxy group, meanwhile, contains 47 galaxies. It also seems to be at a fairly early stage of its evolution, making it an interesting object of study.

Whilst the focus of this image is the spiral galaxy NGC 3783, the eye is equally drawn to the very bright object in the lower right part of this image. This is the star HD 101274. The perspective in this image makes the star and the galaxy look like close companions, but this is an illusion. HD 101274 lies only about 1530 light-years from Earth, meaning it is about 85 thousand times closer than NGC 3783. This explains how a single star can appear to outshine an entire galaxy!

NGC 3783 is a type-1 Seyfert galaxy, which is a galaxy with a bright central region – so it's particularly bright itself, as far as galaxies go. In this image it is recorded by Hubble in incredible detail, from its glowing central bar to its narrow, winding arms and the dust threaded through them, thanks to five separate images taken in different wavelengths of light. In fact, the galactic centre is bright enough to Hubble that it exhibits diffraction spikes, normally only seen on stars such as HD 101274.

Image Credit: ESA/Hubble and NASA, M. C. Bentz, D. J. V. Rosario

Image enhancement: Jean-Baptiste Faure

Spiral Galaxy IC 4633

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The subject of this picture from Hubble is the spiral galaxy IC 4633, located 100 million light-years away from us in the constellation Apus. IC 4633 is a galaxy rich in star-forming activity, as well as hosting an active galactic nucleus at its core. From our point of view, the galaxy is tilted mostly towards us, giving astronomers a fairly good view of its billions of stars.

However, we can't fully appreciate the features of this galaxy – at least in visible light – because it's partially concealed by a stretch of dark dust. This dark nebula is part of the Chamaeleon star-forming region, itself located only around 500 light-years from us, in a nearby part of the Milky Way galaxy. The dark clouds in the Chamaeleon region occupy a large area of the southern sky, covering their namesake constellation but also encroaching on nearby constellations, like Apus. The cloud is well-studied for its treasury of young stars, particularly the cloud Cha I, which has been imaged by Hubble and also by the James Webb Space Telescope.

The cloud overlapping IC 4633 lies east of the well-known Cha I, II and III, and has been called MW9 or the South Celestial Serpent. A vast, narrow trail of faint gas that snakes over the southern celestial pole, it’s much more subdued-looking than its neighbours. It's classified as an integrated flux nebula (IFN) – a cloud of gas and dust in the Milky Way galaxy that's not near to any single star, and is only faintly lit by the total light of all the galaxy's stars. Hubble has no problem making out the South Celestial Serpent, though this image captures only a tiny part of it. For a showy astronomical object like IC 4633, among the South Celestial Serpent's coils clearly isn’t a bad place to hide.

Image Credit: ESA/Hubble and NASA, J. Dalcanton, Dark Energy Survey/DOE/FNAL/DECam/CTIO/NOIRLab/NSF/AURA

Acknowledgement: L. Shatz

Image enhancement: Jean-Baptiste Faure

Seyfert Spiral Galaxy NGC 289

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In the constellation Sculptor lies this large extended spiral galaxy called NGC 289. Despite being around 75 million light-years away, the light of NGC 289 is stunningly captured here by the Dark Energy Camera (DECam) on the Víctor M. Blanco 4-meter Telescope at Cerro Tololo Inter-American Observatory (CTIO), a Program of NSF's NOIRLab. The galaxy's bluish arms reach through the expanse of space over 100,000 light-years, larger than the size of our own Milky Way. It's classified as a Type II Seyfert galaxy with its ripe collections of star formation and bright core, but it's also relatively faint. Studies have found that the galaxy contains large amounts of dark matter, which is a common feature of all galaxies with a low surface brightness. Dark matter is yet to be directly observed, which led the US Department of Energy to build the DECam in order to study the nature of dark matter. Since the conclusion of its survey, DECam has been available to other scientists for use, such as for this image of NGC 289.

Image Credit: CTIO/NOIRLab/DOE/NSF/AURA

Image processing: T.A. Rector (University of Alaska Anchorage/NSF's NOIRLab), J. Miller (Gemini Observatory/NSF's NOIRLab), and M. Zamani (NSF's NOIRLab)

Image enhancement: Jean-Baptiste Faure

Seyfert Spiral Galaxy MCG-01-24-014

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This whirling image features a bright spiral galaxy known as MCG-01-24-014, which is located about 275 million light-years from Earth. In addition to being a well-defined spiral galaxy, MCG-01-24-014 has an extremely energetic core, known as an active galactic nucleus (AGN), so it is referred to as an active galaxy. Even more specifically, it is categorised as a Type-2 Seyfert galaxy. Seyfert galaxies host one of the most common subclasses of AGN, alongside quasars. Whilst the precise categorisation of AGNs is nuanced, Seyfert galaxies tend to be relatively nearby ones where the host galaxy remains plainly detectable alongside its central AGN, while quasars are invariably very distant AGNs whose incredible luminosities outshine their host galaxies.

There are further subclasses of both Seyfert galaxies and quasars. In the case of Seyfert galaxies, the predominant subcategories are Type-1 and Type-2. These are differentiated from one another by their spectra – the pattern that results when light is split into its constituent wavelengths – where the spectral lines that Type-2 Seyfert galaxies emit are particularly associated with specific so-called "forbidden" emission. To understand why emitted light from a galaxy could be considered forbidden, it helps to understand why spectra exist in the first place. Spectra look the way they do because certain atoms and molecules will absorb and emit light very reliably at very specific wavelengths. The reason for this is quantum physics: electrons (the tiny particles that orbit the nuclei of atoms and molecules) can only exist at very specific energies, and therefore electrons can only lose or gain very specific amounts of energy. These very specific amounts of energy correspond to certain light wavelengths being absorbed or emitted.

Forbidden emission lines, therefore, are spectral emission lines that should not exist according to certain rules of quantum physics. But quantum physics is complex, and some of the rules used to predict it use assumptions that suit laboratory conditions here on Earth. Under those rules, this emission is "forbidden" – so improbable that it's disregarded. But in space, in the midst of an incredibly energetic galactic core, those assumptions don't hold anymore, and the "forbidden" light gets a chance to shine out towards us.

Image Credit: ESA/Hubble and NASA, C. Kilpatrick

Image enhancement: Jean-Baptiste Faure

Inner Ring of Galaxy NGC 1097

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ERIS, the Very Large Telescope's newest infrared eye on the sky, captured this stunning image of the inner ring of the galaxy NGC 1097. This galaxy is located 45 million light-years away from Earth, in the constellation Fornax. ERIS has captured the gaseous and dusty ring that lies at the very centre of the galaxy. The bright spots in the ring are stellar nurseries, shown in unprecedented detail. The center of this galaxy is active, with a supermassive black hole that feeds off its surroundings.

This image has been taken through four different filters by ERIS's state-of-the-art infrared imager, the Near Infrared Camera System – or NIX. The filters have been represented here by blue, green, red and magenta, where the last one highlights the compact regions in the ring. To put NIX's resolution in perspective, this image shows, in detail, a portion of the sky less than 0.03% the size of the full Moon.

Image Credit: ESO/ERIS team

Image enhancement: Jean-Baptiste Faure

Spiral Seyfert Galaxy NGC 5495

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The stately sweeping spiral arms of the spiral galaxy NGC 5495 are revealed by the Hubble Space Telescope's Wide Field Camera 3 in this image. NGC 5495, which lies around 300 million light-years from Earth in the constellation Hydra, is a Seyfert galaxy, a type of galaxy with a particularly bright central region. These luminous cores – known to astronomers as active galactic nuclei – are dominated by the light emitted by dust and gas falling into a supermassive black hole.

This image is drawn from a series of observations captured by astronomers studying supermassive black holes lurking in the hearts of other galaxies. Studying the central regions of galaxies can be challenging: as well as the light created by matter falling into supermassive black holes, areas of star formation and the light from existing stars all contribute to the brightness of galactic cores. Hubble's crystal-clear vision helped astronomers disentangle the various sources of light at the core of NGC 5495, allowing them to precisely weigh its supermassive black hole.

As well as NGC 5495, two stellar interlopers are visible in this image. One is just outside the center of NGC 5495, and the other is very prominent alongside the galaxy. While they share the same location on the sky, these objects are much closer to home than NGC 5495: they are stars from our own Milky Way. The bright stars are surrounded by criss-cross diffraction spikes, optical artefacts created by the internal structure of Hubble interacting with starlight.

Image Credit: ESA/Hubble and NASA, J. Greene

Acknowledgement: R. Colombari

Image enhancement: Jean-Baptiste Faure

Barred Spiral Seyfert Galaxy NGC 5728

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Meet NGC 5728, a barred spiral galaxy around 130 million light-years from Earth. This image was captured using Hubble's Wide Field Camera 3 (WFC3), which is extremely sensitive to visible and infrared light. Therefore, this image beautifully captures the regions of NGC 5728 that are emitting visible and infrared light. However, there are many other types of light that galaxies such as NGC 5728 can emit, which WFC3 cannot see.

In this image, NCG 5728 appears to be an elegant, luminous, barred spiral galaxy. What this image does not show, however, is that NGC 5728 is also a monumentally energetic type of galaxy, known as a Seyfert galaxy. This extremely energetic class of galaxies are powered by their active cores, which are known as active galactic nuclei (AGNs). There are many different types of AGNs, and only some of them power Seyfert galaxies. NGC 5728, like all Seyfert galaxies, is distinguished from other galaxies with AGNs because the galaxy itself can be seen clearly. Other types of AGNs, such as quasars, emit so much radiation that it is almost impossible to observe the galaxy that houses them. As this image shows, NGC 5728 is clearly observable, and at optical and infrared wavelengths it looks quite normal. It is fascinating to know that the galaxy's center is emitting vast amounts of light in parts of the electromagnetic spectrum that WFC3 just isn't sensitive to! Just to complicate things, the AGN at NGC 5728's core might actually be emitting some visible and infrared light – but it may be blocked by the dust surrounding the galaxy's core.

Image Credit: ESA/Hubble, A. Riess et al., J. Greene

Image enhancement: Jean-Baptiste Faure

Starburst Spiral Galaxy M61

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The luminous heart of the galaxy M61 (NGC 4303) dominates this image, framed by its winding spiral arms threaded with dark tendrils of dust. As well as the usual bright bands of stars, the spiral arms of M61 are studded with ruby-red patches of light. Tell-tale signs of recent star formation, these glowing regions lead to M61's classification as a starburst galaxy.

Though the gleaming spiral of this galaxy makes for a spectacular sight, one of the most interesting features of M61 lurks unseen at the center of this image. As well as widespread pockets of star formation, M61 hosts a supermassive black hole more than 5 million times as massive as the Sun.

M61 appears almost face-on, making it a popular subject for astronomical images, even though the galaxy lies more than 52 million light-years from Earth. This particular astronomical image incorporates data from not only Hubble, but also the FORS camera at the European Southern Observatory’s Very Large Telescope, together revealing M61 in unprecedented detail. This striking image is one of many examples of telescope teamwork — astronomers frequently combine data from ground-based and space-based telescopes to learn more about the Universe.

Image Credit: ESA/Hubble and NASA, ESO, J. Lee and the PHANGS-HST Team

Image enhancement: Jean-Baptiste Faure

Seyfert Spiral Galaxy M106

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This spectacular image highlights the majestic spiral galaxy M106 (Messier 106) and its diminutive neighbors, as well as a dense field of background galaxies and foreground stars. This may be the best view yet of M106 in its entirety, showing both the warped central disk and the tenuous outer reaches of the galaxy. This celestial snapshot captures the majesty of the spiral galaxy M106, also known as NGC 4258. The image is arguably the best yet captured of the entire galaxy. Obtained using the Nicholas U. Mayall 4-meter Telescope at Kitt Peak National Observatory, a Program of NSF's NOIRLab, this image shows not only the glowing spiral arms, wisps of gas, and dust lanes at the core of the galaxy but also the leisurely twisting bands of stars at its outer edges.

A popular target for amateur astronomers, M106 can be spotted with a small telescope in the constellation Canes Venatici. M106 is similar in size and luminosity to our galactic neighbor the Andromeda Galaxy, but it lies 10 times farther away – more than 20 million light-years from Earth. Though the galaxy measures more than 130 000 light-years from edge to edge, the vast distance between it and the Milky Way renders M106 minuscule when seen from here. Its size in the night sky – if it were visible to the naked eye – is less than that of a penny held at arm's length!

Despite its tranquil appearance, M106 has an unusually energetic inhabitant. The supermassive black hole at the heart of the galaxy – which is about 40 million times as massive as our Sun – is particularly active. As well as consuming vast amounts of gas and dust, the spinning black hole has warped the surrounding disk of gas, churning up vast amounts of material. This process has created the bright, red streamers of gas emanating from the heart of M106, visible in the center of this image.

Accompanying M106 is a pair of dwarf galaxies belonging to the same galaxy group. The loose collection of stars and dust visible in the bottom-right of this image is the small irregular galaxy NGC 4248. Another small galaxy – UGC 7356 – lies to the lower-left of M106 and is dwarfed by its larger neighbor. M106 and its companions are framed by a variety of objects, from foreground stars to background galaxies. Stars from our own galaxy stud the image, easily identified by the criss-cross diffraction patterns surrounding them. In the background, distant galaxies litter the image, some of them visible through the tenuous disk of M106.

As well as being a striking subject for astronomical images, M106 has been instrumental in measuring the scale of the Universe. Astronomers measure distances in the Universe using an interconnected chain of measurements called the cosmic distance ladder, with each rung of the ladder allowing measurements of more and more distant objects. Calibrating these measurements requires objects with a known brightness – such as pulsating stars known as Cepheid variables. Measurements of the Cepheids in M106 have allowed astronomers to calibrate Cepheids elsewhere in the Universe – helping them to measure the distances to other galaxies.

This image was one of the last to be taken with the Mosaic camera before the installation of the Dark Energy Spectroscopic Instrument (DESI), a project of the Department of Energy's Office of Science and Lawrence Berkeley National Laboratory.

Image Credit: KPNO/NOIRLab/NSF/AURA

Acknowledgment: PI: M.T. Patterson (New Mexico State University)

Image processing: T.A. Rector (University of Alaska Anchorage), M. Zamani & D. de Martin

Image enhancement: Jean-Baptiste Faure

Seyfert Galaxy IC 5063

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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 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 being cast into space by an inner tube-shaped ring, or torus, of dusty material surrounding the black hole. IC 5063 resides 156 million light-years from Earth.

Image Credit: NASA, ESA, and W.P. Maksym (CfA)

Image enhancement: Jean-Baptiste Faure

Barred Spiral Galaxy M77

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ESO's Very Large Telescope (VLT) has captured a magnificent face-on view of the barred spiral galaxy M77 (Messier 77). The image does justice to the galaxy's beauty, showcasing its glittering arms criss-crossed with dust lanes – but it fails to betray M77's turbulent nature.

Image Credit: ESO

Image enhancement: Jean-Baptiste Faure

Spiral Galaxy M106 Composite Image

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NGC 4258, also known as M106, is a galaxy about 23 million light-years away and is home of a giant black hole. This galactic fireworks display is taking place in M106, a spiral galaxy like our own Milky Way. This galaxy is famous, however, for something that our galaxy doesn't have – two extra spiral arms that glow in X-ray, optical and radio light. These features, or anomalous arms, are not aligned with the plane of the galaxy, but instead intersect with it.

The anomalous arms are seen in this new composite image, where X-rays from NASA's Chandra X-ray Observatory are blue, radio data from the NSF's Karl Jansky Very Large Array are purple, optical data from NASA's Hubble Space Telescope are yellow and infrared data from NASA's Spitzer Space Telescope are red.

A new study made with Spitzer shows that shock waves, similar to the sonic booms from supersonic planes, are heating large amounts of gas – equivalent to about 10 million suns. What is generating these shock waves? Researchers think that the supermassive black hole at the center of NGC 4258 is producing powerful jets of high-energy particles. These jets strike the disk of the galaxy and generate shock waves. These shock waves, in turn, heat the gas – composed mainly of hydrogen molecules – to thousands of degrees. The Chandra X-ray image reveals huge bubbles of hot gas above and below the plane of the galaxy. These bubbles indicate that much of the gas that was originally in the disk of the galaxy has been heated and ejected into the outer regions by the jets from the black hole.

The ejection of gas from the disk by the jets has important implications for the fate of this galaxy. Researchers estimate that all of the remaining gas will be ejected within the next 300 million years – very soon on cosmic time scales – unless it is somehow replenished. Because most of the gas in the disk has already been ejected, less gas is available for new stars to form. Indeed, the researchers used Spitzer data to estimate that stars are forming in the central regions of NGC 4258, at a rate which is about ten times less than in the Milky Way galaxy.

The European Space Agency's Herschel Space Observatory was used to confirm the estimate from Spitzer data of the low star formation rate in the central regions of NGC 4258. Herschel was also used to make an independent estimate of how much gas remains in the center of the galaxy. After allowing for the large boost in infrared emission caused by the shocks, the researchers found that the gas mass is ten times smaller than had been previously estimated. Because NGC 4258 is relatively close to Earth, astronomers can study how this black hole is affecting its galaxy in great detail.

Image Credit: X-ray: NASA/CXC/Caltech/P.Ogle et al; Optical: NASA/STScI; IR: NASA/JPL-Caltech; Radio: NSF/NRAO/VLA

Image enhancement: Jean-Baptiste Faure

Active Spiral Galaxy ESO 021-G004

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This swirling mass of celestial gas, dust, and stars is a moderately luminous spiral galaxy named ESO 021-G004, located just under 130 million light-years away. This galaxy has something known as an active galactic nucleus.

While this phrase sounds complex, this simply means that astronomers measure a lot of radiation at all wavelengths coming from the centre of the galaxy. This radiation is generated by material falling inwards into the very central region of ESO 021-G004, and meeting the behemoth lurking there – a supermassive black hole.

As material falls towards this black hole it is dragged into orbit as part of an accretion disc; it becomes superheated as it swirls around and around, emitting characteristic high-energy radiation until it is eventually devoured. The data comprising this image were gathered by the Wide Field Camera 3 aboard the Hubble Space Telescope.

Image Credit: ESA/Hubble and NASA, D. Rosario et al.

Image enhancement: Jean-Baptiste Faure

Interacting Spiral Galaxy NGC 7674

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NGC 7674, seen just below the center in this image, is the brightest and largest member of the so-called Hickson 96 compact group of galaxies. This stunning Hubble image shows a spiral galaxy nearly face-on. The central bar-shaped structure is made up of stars. The shape of NGC 7674, including the long narrow streamers seen to the left of and below the galaxy can be accounted for by tidal interactions with its companions. NGC 7674 forms a pair with its smaller companion NGC 7674A, which lies 34 arcseconds to the north.

NGC 7674, also known as Markarian 533, has a powerful active nucleus of the kind known as a type 2 Seyfert that is perhaps fed by gas drawn into the centre through the interactions with the companions. NGC 7674 falls into the family of luminous infrared galaxies and is featured in Arp's Atlas of Peculiar Galaxies as number 182. It is located in the constellation of Pegasus, the Winged Horse, about 400 million light-years away from Earth.

This image is part of a large collection of 59 images of merging galaxies taken by the Hubble Space Telescope.

Image Credit: NASA, ESA, the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration and A. Evans (University of Virginia, Charlottesville/NRAO/Stony Brook University)

Image enhancement: Jean-Baptiste Faure

Active Galaxy Markarian 817

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Rings of brilliant blue stars encircle the bright, active core of this spiral galaxy, whose monster black hole is blasting material into space at over 14 million kilometers per hour. Viewed nearly face-on, the galaxy, called Markarian 817, shows intense star-forming regions and dark bands of interstellar dust along its spiral arms.

Observations by the new Cosmic Origins Spectrograph (COS) aboard the Hubble Space Telescope captured the powerful outflow of material from this galaxy. The COS spectrum of Markarian 817 highlights the outflow's dynamic nature. A gas cloud containing hydrogen that was detected in Hubble data taken in 1997 does not appear in the COS observation because the cloud has apparently been driven out by an outflow of material from the galaxy. This discharge is being powered by a huge disc of matter encircling the supermassive black hole, which is 40 million times more massive than our Sun. The disc is driving the material out of the galaxy through powerful winds, produced by streams of charged particles. Some of the outflow rains back onto the galaxy. The rest settles into the intergalactic gas.

Astronomers want to know how much of the outflow lands in the galaxy and how much escapes into intergalactic space. To achieve this, they need high-quality spectroscopic observations to detect the signatures of the outflowing material, which includes carbon, nitrogen and oxygen. This will allow them to determine the composition, location and dynamics of the winds that distribute the material.

Markarian 817 is 430 million light-years away in the northern constellation of Draco. COS observed the galaxy using its far-ultraviolet detector to distinguish the outflow from the galaxy's core. NASA astronauts installed COS during Servicing Mission 4.

The Hubble image was taken with the Wide Field Camera 3. The composite image was made by using filters that isolate light from the blue, green and infrared portions of the spectrum, as well as emission from glowing hydrogen. The Hubble observations are part of the Hubble Servicing Mission 4 Early Release Observations.

Image Credit: NASA, ESA and the Hubble SM4 ERO Team

Image enhancement: Jean-Baptiste Faure

Barred Spiral Galaxy UGC 6093

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This image, captured by the Hubble Space Telescope's Wide Field Camera 3 (WFC3), shows a galaxy named UGC 6093. As can be easily seen, UGC 6093 is something known as a barred spiral galaxy – it has beautiful arms that swirl outwards from a bar slicing through the galaxy's center. It is classified as an active galaxy, which means that it hosts an active galactic nucleus, or AGN: a compact region at a galaxy's center within which material is dragged towards a supermassive black hole. As this black hole devours the surrounding matter it emits intense radiation, causing it to shine brightly.

But UGC 6093 is more exotic still. The galaxy essentially acts as a giant astronomical laser that spews out light at microwave, not visible, wavelengths – this type of object is dubbed a megamaser (maser being the term for a microwave laser). Megamasers such as UGC 6093 can be some 100 million times brighter than masers found in galaxies like the Milky Way.

Hubble's WFC3 observes light spanning a range wavelengths – from the near-infrared, through the visible range, to the near-ultraviolet. It has two channels that detect and process different light, allowing astronomers to study a remarkable range of astrophysical phenomena; for example, the UV-visible channel can study galaxies undergoing massive star formation, while the near-infrared channel can study redshifted light from galaxies in the distant Universe. Such multi-band imaging makes Hubble invaluable in studying megamaser galaxies, as it is able to untangle their intriguing complexity.

Image Credit: ESA/Hubble and NASA

Image enhancement: Jean-Baptiste Faure

Spiral Galaxy NGC 4388

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The constellation of Virgo 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 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 locations of young stars, indicating that NGC 4388 has hosted recent bursts of star formation. Despite the mixed messages, NGC 4388 is classified as a spiral galaxy. Its unusual combination of features are thought to have been caused by interactions between NGC 4388 and the Virgo Cluster. Gravitational interactions – from glancing blows to head-on collisions, tidal influencing, mergers, and galactic cannibalism – can be devastating to galaxies. While some may be lucky enough to simply suffer a distorted spiral arm or newly-triggered wave of star formation, others see their structure and contents completely and irrevocably altered.

Image Credit: ESA/Hubble and NASA

Image enhancement: Jean-Baptiste Faure

Spiral Seyfert Galaxy NGC 6814

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Spiral galaxies together with irregular galaxies make up approximately 60% of the galaxies in the local Universe. However, despite their prevalence, each spiral galaxy is unique – like snowflakes, no two are alike. This is demonstrated by the striking face-on spiral galaxy NGC 6814, whose luminous nucleus and spectacular sweeping arms, rippled with an intricate pattern of dark dust, are captured in this Hubble Space Telescope image. NGC 6814 has an extremely bright nucleus, a telltale sign that the galaxy is a Seyfert galaxy. These galaxies have very active centers that can emit strong bursts of radiation. The luminous heart of NGC 6814 is a highly variable source of X-ray radiation, causing scientists to suspect that it hosts a supermassive black hole with a mass about 18 million times that of the Sun. As NGC 6814 is a very active galaxy, many regions of ionised gas are studded along its spiral arms. In these large clouds of gas, a burst of star formation has recently taken place, forging the brilliant blue stars that are visible scattered throughout the galaxy.

Image Credit: ESA/Hubble and NASA

Acknowledgement: Judy Schmidt (Geckzilla)

Image enhancement: Jean-Baptiste Faure