As far as galaxies go, our Milky Way is a relatively quiet place. Sure, there are star-forming regions that are active right now within our galactic plane, giving birth to thousands of new stars at once over timescales of a few million years, including relatively nearby in places like the Orion Nebula. But most of our galaxy isn’t forming stars, just a few select locations along our spiral arms. In terms of the overall star-formation rate, we form less than one solar mass’s worth of new stars with each year that passes. Even our galactic center is relatively quiet, with just the occasional “blip” in X-ray light emanating from our own supermassive black hole.

Across the Universe, however, there are many galaxies that are much more active than we are. This includes:

• galaxies that are undergoing intense episodes of star-formation across large regions,
• galaxies where gas in the central regions are rapidly forming new stars all at once,
• and galaxies whose central nucleus is actively feeding right now, creating copious high-energy signatures that our own galaxy lacks.

While there are a few active galaxies that are extremely close by — Centaurus A, the Circinus galaxy, and NGC 4395, for example — there’s a giant, face-on example of a galaxy that has uniquely remarkable, energetic features not found in any other combination known to date: Messier 77, sometimes known as the Squid Galaxy. Discovered way back in 1780 by Pierre Méchain, it just got its deepest-ever look courtesy of JWST and a science team led by Adam Leroy.

Here’s what makes this object so remarkable to begin with, followed by what JWST newly spotted inside with its unprecedented infrared power.

This Hubble image of nearby spiral galaxy Messier 77 showcases a galaxy larger, brighter, and with more stars than the Milky Way. Its sweeping spiral arms and bright central nucleus are prominent features, as are the bright pink star-forming regions found in a few locations away from the galactic center.

It might seem like a lifetime ago, but as recently as mid-2022, the best-ever images we had acquired of distant galaxies didn’t come from JWST, but rather by a NASA telescope launched way back in 1990: Hubble. Specializing in visible light wavelengths, Hubble was able to reveal features like the ones showcased above:

• a bright, central nucleus,
• swirling dark, dusty lanes lining a series of spiral arms,
• star-forming regions glowing with a characteristic pink color,
• dotted with a series of young, hot, bright blue stars,
• where the cumulative starlight from all the stars inside fades toward a faint, nebulous glow as you move from the center to the outskirts of the galaxy.

This galaxy might look like it’s face-on to us, with the spiral arms clearly visible, but in reality this galaxy is inclined to our line-of-sight at about 40 degrees, and is substantially larger than the Milky Way: at about 140,000 light-years across.

However, what’s perhaps most remarkable about this galaxy cannot be revealed with visible light alone: it has an active galactic nucleus at its core, surrounded by hot dust, and emits light that’s highly polarized. It’s one of the closest, brightest, and most prominent examples of a Type II Seyfert galaxy, in which — unlike a quasar — the disk of the galaxy itself is clearly and easily resolvable.

This composite image of Messier 77 showcases a mix of visible light and near-infrared light views, acquired with the ESO’s Very Large Telescope. Inside, a series of features that cannot be seen in visible light alone, such as a central galactic bar, appear.

The galaxy has been imaged by a variety of telescopes and instruments over time, which are capable of probing wavelengths and faint features that are invisible at optical wavelengths and to observatories with very narrow fields-of-view. Above, you can see an image of Messier 77 from the ground-based Very Large Telescope, which showcases several features that cannot be seen in the earlier Hubble image. They include:

• a prominent central bar,
• a larger, more extended sweeping set of arms and stars that surround the central galactic component,
• lines and dots that indicate new star-forming regions that extend far beyond what Hubble could see,
• and a population of hot dust that surrounds the central galactic nucleus.

It also reveals just how spectacularly the central region of this galaxy outshines the rest of the galaxy, including the main galactic disk and the far-flung structures that appear much fainter than the interior of the galaxy itself.

There’s also a pink ring surrounding the central nucleus: visible in infrared light but not in optical wavelengths of light. The inner ends of the two spiral arms create this ring, known as a starburst ring, where gas within those dense spiral arms gets converted into hot, young stars. Even though the stars themselves aren’t visible, they heat the dust surrounding them, which causes the “ring” to glow at infrared wavelengths.

This composite image of galaxy Messier 77 is one of the nearest and brightest galaxies to contain an active, growing supermassive black hole. Strong winds drive matter away from the galactic center, which is dust obscured and also emits X-rays and (to a lesser extent) gamma rays. Along with optical and radio data, this galaxy is seen giving off emissions from across the electromagnetic spectrum.

The central region of Messier 77, which already appears bright, albeit dust obscured, at optical wavelengths is one of the most energetic galactic engines in the nearby Universe. Its emissions were first spotted at radio wavelengths, but with the advent of space-based observatories, we discovered that it was a strong emitter of X-rays as well. In gamma-rays, at the highest energies of all, a small amount of emissions are also seen, leading to a picture where a dense, dust-rich torus of gas surrounds the central black hole. It doesn’t have a clear set of gamma-ray jets, like many active galaxies are observed to have, indicating that the dust surrounding the central black hole is thick enough to absorb most of them.

There are a series of smaller galaxies that surround Messier 77, and this galaxy’s gravity is strong enough to twist and distort them. While emissions are seen all across the electromagnetic spectrum from this galaxy, there’s another way that an active galaxy — at least in principle — could be detected: through the emission of neutrinos. Historically, neutrinos arrive from all locations in space, and were detected:

• from nuclear reactors and particle accelerators here on Earth,
• from the Sun,
• and from all over the sky, somewhat randomly, in the form of atmospheric neutrinos.

In 1987, we detected our first source of neutrinos from beyond the Solar System, when a supernova went off just 165,000 light-years away. In 2018, the IceCube neutrino observatory spotted an excess of neutrinos from a distant blazar: TXS 0506+056. But then, in 2022, a fourth astrophysical source of neutrinos joined the club. In a great surprise, it was this very galaxy that was the culprit: Messier 77.

The location of Messier 77 (NGC 1068) along with the excess neutrino signal identified as coming from it, over and above the diffuse neutrino background seen elsewhere. This evidence marks the first non-blazar, non-supernova neutrino source seen outside of our Solar System, coming from a galaxy located 45-47 million light-years away.

A total of 79 excess neutrino events were detected and identified as originating from this object: the only statistically significant detection of continuous neutrino emissions in the nearby Universe. This combination, of significant neutrino emission but with only very little gamma-ray emission, may be particular to objects like this galaxy: with active supermassive black holes, but that are surrounded by significant quantities of dust. There are suspected to be many nuclear reactions taking place around the central black hole itself, producing both energetic neutrinos and high-energy light, but only the neutrinos can escape, as the dust absorbs and attenuates the gamma-rays, letting only a tiny sliver of them through.

Since IceCube’s first detection of extragalactic neutrinos, two additional blazars have been seen in neutrinos as well: PKS 1424+240 and GB6 J1542+6129. Their signals are less strong than from either Messier 77 or from TKS 0506+056, but they still stand out against the background neutrino flux. However, Messier 77 remains unique as a strong neutrino source without a significant gamma-ray counterpart, suggesting that configurations such as the one found in this system are either rare, transient, or both.

In 2018, a supernova appeared in galaxy Messier 77 as well: an unusual, irregular-type supernova known as SN 2018ivc, which showed an unprecedented re-brightening about a year after the initial explosion, giving a hint as to how unusual and remarkable the environment within this galaxy truly is.

This composite of 19 separate nearby, face-on spiral galaxies all located within 100 million light-years of ourselves is a result of the PHANGS program, where multi-wavelength observatories including Hubble, the VLT, ALMA, and now JWST are all taking data of the same objects in an effort to map out the stars, star-forming regions, gas, dust, and even diffuse atoms that exist within these objects. These JWST views have revealed millions of new stars, 100,000 star clusters, and the most exquisite dust maps ever constructed within these galaxies.

However, as is so often the case, a new, more powerful observatory has the power to change everything, and can add more to the cosmic story of an object than we ever would have expected. JWST has already viewed a large number of nearby galaxies in great detail in either near-infrared or mid-infrared light, or both. Mid-infrared light can trace out warm and even cool dust, showing the future sites of star-formation within a galaxy. Near-infrared light traces out significantly heated gas and dust, while still displaying the locations of stars, particularly luminous-but-cool evolved, giant stars, like red giants and supergiants.

But there are other things that JWST reveals as well. For example, if you have something that behaves as an extremely luminous point source — where it takes up just one pixel in JWST’s detectors — then the telescope’s design will diffract that light into eight diffraction spikes (six large ones and two smaller ones). In some cases, that can point to an unresolved central nucleus that indicates the site of intense new star-formation. In other cases, particularly at mid-infrared wavelengths, it corresponds to the location of an active supermassive black hole. In fact, several new (candidate) supermassive black holes have been identified in exactly this way: by JWST revealing that now-classic diffraction spike pattern at the centers of galaxies.

This JWST mid-infrared picture of galaxy Messier 77 reveals an enormous number of never-before-seen features within this galaxy. The prominent diffraction spikes were expected, but the bright orange features revealed by these mid-infrared observations show the locations where heating is most significant, most likely pointing to an internal population of new stars shrouded by dust.

So when JWST examined Messier 77 at long last, it didn’t come as a total surprise to discover that in mid-infrared wavelengths, an enormously strong signal of those eight diffraction spikes appeared. That makes sense; as a Type II Seyfert galaxy, there pretty much has to be an active black hole at the galaxy’s center, and there’s likely new stars forming in that central region as well, albeit shrouded by dust.

But this image also reveals features we couldn’t have expected without taking these views. The orange features lining the inner arms (and dotting the outer regions) of this galaxy showcase sites of recent star-formation, where the orange regions show where the dust has been heated. Blue regions correspond to colder dust: locations where future star-formation may occur, but where it isn’t happening right now. And the dark, black regions represent regions where stars formed longer ago, and where the star-forming material has all been blown away out of them.

Prominently, close to the galactic center, you can see what appears to be a “ring” of orange lining the dust. This is most likely the corresponding mid-infrared signature of what we had previously called a “starburst ring” within this galaxy, providing a more end-to-end picture of what’s happening.

This image showcases JWST’s near-infrared (NIRCam) view of the Squid Galaxy, Messier 77. While the diffraction spikes are still present, they’re far less prominent than in the mid-infrared image, suggesting that there is indeed a contribution from more than just the active black hole in the central nucleus. More tenuous features can be seen as well, as the gas and dust must be heated to higher temperatures to be revealed in near-infrared light as opposed to mid-infrared light. The faint glow of stars can be seen at near-infrared wavelengths as well, along with the prominent “starburst ring” surrounding the central nucleus.

In near-infrared wavelengths, JWST has its NIRCam instrument to take observations: with a larger field-of-view and higher resolution than at mid-infrared wavelengths with MIRI. In these shorter wavelengths, a different set of features appears.

• First, the central nucleus still emits diffraction spikes, indicating that in addition to the active black hole, there is likely a population of newly-forming stars at the galactic center.
• Second, the “starburst ring” appears more clearly defined and prominently, showcasing in bright orange where the most intense episodes of star-formation are occurring.
• Third, interior to that ring, a thick line-like feature can be observed: the best-ever view of the central galactic bar.
• Fourth, the white-colored glow allows us to track the stellar density of this galaxy as a function of distance from the center, showcasing how comparatively dense the interior regions are versus the sparser outer reaches of the galaxy.
• Next, the misalignment between some prominent outer stellar features (white dots and swirls) and the locations of new star formation (in oranges and reds) shows the difference between where recently-formed stars are located versus where ongoing sites of star formation can be found.
• And finally, the incredible resolution of NIRCam allows us to make the best-ever measurements of the size of the starburst ring, which now comes in at just over 6000 light-years in diameter. Despite the appearance of this galaxy, the ring is actually very circular: a reminder that our view of this galaxy isn’t truly face-on, but rather is inclined at around 40 degrees.

One exciting thing we can do, with both NIRCam and MIRI data in hand, is display them together, leading to the composite image you see below.

This MIRI + NIRCam composite image of the Squid Galaxy, Messier 77, shows off many prominent features of this galaxy together. The diffraction spikes from NIRCam and MIRI are combined, and the central bar appears prominently, surrounded by the starburst ring. Significant dust lanes can be seen against the backdrop of stars, with gaps in the dust and the hottest, densest dusty regions appearing alongside one another. On the outskirts, background galaxies are revealed, appearing only because of the inclusion of NIRCam data.

When you put all of the data together, at once, a coherent picture of this galaxy’s physics — the best one we’ve ever been able to construct — emerges. The severity of the brightness of the central region, corresponding only to the innermost 10,000 light-years or so of a galaxy some 140,000 light-years across, outshines the rest of the galaxy in every way. The starlight, as seen in white, is brighter. The near-infrared emissions from heated material, shown in bright orange, is dominated by the starburst ring. The central nuclear emissions, appearing in both NIRCam and MIRI data, is the only source of its type within this galaxy.

Meanwhile, in the remainder of the galaxy, you can see where the mid-infrared and near-infrared features both do match up (in terms of where the gas-and-dust of various temperatures are) and where there’s a mismatch (between the stars, in white, and the dust, in orange). This makes sense, because the science reason for investigating this galaxy in such great detail with JWST, as well as many other galaxies as part of the same study, is to determine what the physics of the baryon cycle within local galaxies is. This involves the physics of how gas flows within galaxies and leads to the formation of new stars, as well as how star-formation feeds back onto that gas, heats it, and returns it to the interstellar medium. This process is always in action, and here in Messier 77, we get a “snapshot” of a spectacular example of it occurring, galaxy-wide and up close, in real-time.

A spiral galaxy typically consists of four main gaseous regions within the disk: diffuse atomic gas, dense molecular gas, stars and star clusters, and ionized regions of matter arising from energy injections from star-forming regions, young stars, and stellar cataclysms. JWST, along with the other PHANGS data sources, helps reveal different aspects of this life cycle, but once a galaxy’s gas is gone and no new gas reservoirs fall inside, star-formation ends permanently.

Still, the most exciting part of getting to see Messier 77 up close and in high resolution like this is the new views of the center of this object. These views of the hot gas represent the highest-resolution views we’ve ever seen. The pile-up of gas in the starburst ring surrounding the central black hole is a remarkable feature, revealed in greater detail than ever before with this study. In particular, the numerous “orange bubbles” that blur together in lower-resolution telescopes lining that ring can be resolved individually with JWST, and in particular with NIRCam, highlighting and exposing these features to astronomers better than ever before.

One of the biggest questions astronomers still have concerns the relationship between star-formation within a galaxy and the active black holes often found within them. How does injected energy from the black hole feed back onto the material surrounding it, and how and when does it lead to a cessation of star-formation? Where and when will star-formation cease in this galaxy, and how can these observations help us make sense of the galaxies we see farther away: where we can’t resolve them in the detail we can with such a close galaxy as Messier 77?

It’s worth remembering that the data we acquire from JWST often helps us construct spectacularly beautiful images, but that’s not the reason we do it; that’s just an exciting side-effect. The real goal is to learn about the Universe: how it works, how it came to be the way it is today, and how it will evolve into the future. With each new observation that we take, we move ever-closer to those goals, uncovering new, deeper questions to ask and investigate along the way. In that fashion, science will never cease to provide fresh nourishment for minds curious enough to investigate the Universe.

This article Cosmic beacon unveiled inside nearby active galaxy by JWST is featured on Big Think.

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