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Ferrebeekeeper has featured some mind-bogglingly strange astronomic entities before—black holes, ultra-dense stellar remnants, hyper-giant stars with a million times the mass of the sun, colliding neutron stars—but today we move up to a vastly greater order of magnitude! Astronomers have just discovered a new class of galaxy which emits energy at unimaginable levels. Using NASA’s Wide-field Infrared Survey Explorer (WISE), scientists have discovered what are being tentatively called “extremely luminous infrared galaxies” (ELIRGs).
One of these galaxies (with the not-very-snappy designation “WISE J224607.57-052635.0”) is producing 10,000 times more energy than the Milky Way, despite being much smaller than our familiar home. The newly discovered galaxy is putting out more energy than 10 trillion suns (or, more correctly, I should say it was putting out the energy of ten trillion main-sequence yellow stars). Scientists consider it the brightest known galaxy in the universe.
WISE J224607.57-052635.0 is 12.5 billion light-years away. Since the universe is 13.8 billion years old, what we are now seeing dates to a whole different era of galactic dynamics. Today maybe WISE J224607.57-052635.0 is a burned-out remnant…or a perfectly respectable middle-aged galaxy like the Milky Way. Who knows? But twelve-and-a-half billion years ago it was releasing an inconceivable amount of energy—so much so that astronomers are having trouble adjusting their theories to it. Perhaps some embryonic galaxies have black holes which gobble up stars at a much greater rate than initially thought or, alternately, some unknown set of circumstances has allowed the black hole (or holes?) at the center of WISE J224607.57-052635.0 to somehow surpass the theoretical threshold of black hole feeding.
Clearly astronomers are going to be sorting out what exactly happened out there for quite a while, but in the meantime, when you look up at the night sky remember you are looking at an invisible fountain of energy ten trillion times brighter than the sun. [Ooh, I made myself dizzy]
We have some new galactic neighbors! Well, actually maybe “new” is not the right term: they have been there for a long time but we only just now noticed. Astronomers are reporting the discovery of nine dwarf satellite galaxies orbiting the Milky Way like remoras stuck to a cosmic shark. These nine miniature galaxies are additional to the well-known Large and Small Magellanic Clouds—two dwarf galaxies which are located right next to the Milky Way (being respectively 160,000 and 200,000 light years away).
The new dwarf galaxies were discovered by a team of astronomers poring over data recovered from the Dark Energy Survey (a super-high resolution digital array which is part of the Victor M Blanco telescope in the Andes). The closest is a mere 97,000 light years from the Milky Way whereas the farthest lies 1.2 million light years away from us. The dwarf galaxies are a billion times fainter than the Milky Way. They are made up of millions (or hundreds of millions or even billions) of stars but are insignificant in size compared to the hundreds of billions of stars which constitute a true galaxy. Scientists believe that there are hundreds of similar miniature galaxies and pseudo-galaxies near the Milky Way, but they are dark and difficult to find (comparitively speaking).
I have been saying “dwarf galaxies” because I like the way it sounds (like the new galaxies live together in the woods in a little hut and work in the mines!), but actually only three of the new companions are definitely dwarf galaxies. The remaining six structures may be dwarf galaxies or they may merely be globular clusters—a far less euphonic phrase which indicates a group of stars which orbits a galactic core as a satellite. Unlike globular clusters, dwarf galaxies are held together by the gravitational mass of large quantities of dark matter (um, assuming it actually exists). Indeed dwarf galaxies seem to contain far greater quantities of dark matter than actual galaxies. This makes the newly discovered galactic neighbors a potentially useful focus for studying the properties of dark matter and refining our model of the universe.
Fifty million light years away from Earth is the dwarf galaxy M60-UCD1. This tiny globular galaxy is 300 light years across–whereas our own beloved spiral galaxy, the Milky Way, is 120,000 light years in diameter! Yet within that 300 million light year sphere, M60-UCD1 is a crazy place. Despite its (comparatively) tiny area, the dwarf galaxy is teaming with stars: astronomers estimate it contains 140 million star systems. If Earth were located in M60-UCDI, the night sky would positively glow with millions of visible tars (as opposed to the measly 4000 which are visible to the naked eye in our present location). This is all quite odd, yet only recently did astronomers discover the strangest thing about M60-UCDI. At the center of the tiny galaxy is a supermassive black hole which weighs more than twenty million suns. To quote the European Space Agency’s website, “The supermassive black hole at the centre of M60-UCD1 makes up a huge 15 percent of the galaxy’s total mass, and weighs five times that of the black hole at the center of the Milky Way.”
Astronomers speculate that something went terribly wrong to form this oddball of a galaxy. A prime culprit is Messier 60, a large scary galaxy which lurks near the little dwarf galaxy. The black hole at the center of Messier 60 is 4.5 billion times the size of our Sun! Perhaps once upon a time M60-UCDI was a normal galaxy with billions of stars…till it wandered too close to Messier 60. The larger galaxy tore off the majority of the stars which made up M60-UCDI and added them to itself (while Messier 60’s black hole swallowed up its fair share of star systems). It is a horrifying image of galactic bullying! Why can’t we all get along?
Twelve million light years from Earth lies Messier 82, a starburst galaxy 5 times more luminous than the entire Milky Way galaxy. Messier 82 (AKA M82) is a very happening and dynamic galaxy: stars are being created there at an exceptionally high rate—most likely because the galaxy is “interacting” (or possibly colliding) with its neighboring galaxy M81. In 2005, the Hubble Space Telescope detected nearly 200 massive starburst clusters near M82’s center. Within these huge masses of dust and gas, stars are being birthed (and dying) at an astonishing rate. The high energy released by this cosmic upheaval is nearly constant and the outflow of charged particles from M82 is evocatively known as “superwind”.
In 2010, astronomers working at Jodrell Bank Observatory in England discovered a mystery at the heart of M82: an unknown object was emitting high energy electromagnetic radiation in a pattern unlike anything else so far observed in the universe. The mystery object appeared to be moving at 4 times the speed of light (which is, of course, quite impossible according to the standard model of the universe. Newscientist.com offered the following explanation (of sorts) for the mystery object’s perceived velocity:
Such apparent “superluminal” motion has been seen before in high-speed jets of material squirted out by some black holes. The stuff in these jets is moving towards us at a slight angle and travelling at a fair fraction of the speed of light, and the effects of relativity produce a kind of optical illusion that makes the motion appear superluminal.
At present, the best explanation astronomers have for the mystery is that it is some sort of microquasar or black hole which is interacting in an unusual way with the tumultuous mass within a starburst cluster. At present, the mystery is unexplained.
However, at present, M82 is doing entirely different things which have captured the attention of the international astronomy community. On January 21st, 2014, Steve Fossey and a group of his students at University College London spotted a colossal explosion within M82. The event was quickly identified as a type Ia supernova, a bright and consistently energetic star explosion which occurs in binary stars where at least one star is a white dwarf (the dead, but energetic fragment of a larger star). CBS News explains the phenomenon and its historical significance:
[When a] white dwarf siphons off too much mass from its companion star, a runaway nuclear reaction begins inside the dead star, leading to a brilliant supernova. Because Type Ia supernovas are believed to shine with equal brightness at their peaks, they are used as “standard candles” to measure distances the universe.
The supernova in M82 is the nearest supernova of its type observed since Supernova 1987A was spotted in February 1987 in the Large Magellanic Cloud (the dwarf galaxy which is companion to the Milky Way). Telescopes around Earth are turning towards Ursa Major (where M82 is located in the sky). Although the supernova is big news here, it is a very stale story in M82 where this all happened 12 million years ago.
News of the cosmos frequently involves inconceivably large numbers or gigantic objects beyond human imagination. This is particularly true of galaxies–gigantic systems of stars, gas clouds, black holes, and exotic unknown dark matter. Even the tiniest dwarf galaxies have tens of millions of stars and our lovely home galaxy, the Milky Way, has approximately 300 billion star systems! However the universe is a mysterious place and it frequently refutes conventional wisdom and prior expectations. This week astronomers from Hawaii’s Keck Observatory announced that they had discovered a ridiculously little galaxy with only a thousand stars. The adorable miniature galaxy, which has been dubbed Segue 2 is not a star cluster because it is surrounded by its own halo of dark matter, but it is many orders of magnitude smaller than any known galaxy. Astronomers are trying to determine whether it is a scrap of a larger galaxy which was ripped apart (!) or whether it is a baby galaxy which never fully coalesced. Astronomers hope that by learning more about Segue 2 and other hypothesized tiny galaxies they can find out more about the creation of the universe and the formation of elements.
Gamma rays have the most energy of any wave in the electromagnetic spectrum (which includes more familiar radiation such as x-rays, radio, and visible light). The wavelength of gamma rays (10 picometers and smaller–which is a subatomic scale) is less than that of any other sort of EM radiation. Such radiation is created in the event horizons of massive black holes and during the destruction of gigantically massive stars. Comic book enthusiasts know gamma rays as the mysterious super force which created and empowers the incredible hulk, although actual cell biologists recognize gamma rays as ionizing radiation–supremely hazardous to living entities.
On Saturday, April 27, the Fermi Gamma-Ray Telescope (a NASA satellite which orbits around Earth) detected a sudden brilliant surge of gamma radiation from the collapse of a super massive star in a galaxy 3.6 billion light-years away. Gamma ray burst travel in vastly powerful beams which are very narrow–an effect which is a result of the shape of supernovae, as illustrated in the picture above. Our old friend Eta Carinae has probably exploded and produced such a burst by now. A gamma ray bust from a nearby Wolf–Rayet star (any star with more than 20 solar masses) would most likely fry away life on our planet if it were aimed directly at Earth, but such explosions are increasingly rare as the universe ages. Scientists can monitor gamma bursts from the edge of the universe (i.e. the distant past) but such a powerful event has never been monitored by our modern satellites and observatories from a middle range until now.
As the gamma ray burst fades (and the astronomy community begins to assess the initial data) other observatories will be on the lookout for the next wave of phenomena associated with the supernova. Most of the energy of a supernova explosion is believed to be dissipated as neutrinos (esoteric subatomic particles which react very little with physical matter in this universe). Fortunately humankind now possesses a sophisticated neutrino observatory on the South Pole where thousands of sensors are imbedded within a vast amount of Antarctic ice. In the rare cases where neutrinos interact with matter, they produce a cascade of charged particles which can emit Cherenkov radiation (familiar as the spooky blue glow in a nuclear reactor). Understanding the neutrino signature of such an event would potentially further our understanding of the physical parameters of existence.
Also, a luminous flash of less energetic radiation (x-rays, radio waves, light, and so forth) should be following the gamma ray burst. We understand these parts of supernovae better (since they are visible from many angles unlike the linear gamma ray bursts), but it should still be pretty–and round out our understanding of the full astronomical event.
Brian May is an astrophysicist who pursued a career in music. He is the guitarist for the rock band Queen and he is more famous for writing “Fat Bottomed Girls”, “We Will Rock You”, & “Who Wants to Live Forever” than for anything he wrote while obtaining his Astrophysics degrees. Brian was popularizing Galaxy Zoo on his blog (Galaxy Zoo is an online project which seeks public help in classifying vast numbers of galaxies. A Dutch fan, Hanny van Arkel (a schoolteacher by trade), became interested in the project and started working on the site when she spotted a huge weird glowing green thing below spiral galaxy IC 2497. She presented her findings to professional astronomers, who were also perplexed by the ghostly shape. They duly named the object in her honor “Hanny’s Voorwerp” (which is Dutch for “Hanny’s thing”).
So what is Hanny’s Voorwerp? The leading theory is that the supermassive black hole in the center of IC 2497 created huge jets of energy and gas as it (messily) devoured great masses of matter at the center of that galaxy. These esoteric plumes interacted with an unrelated stream of gaseous matter hundreds of thousands of light years long (which is longer than our galaxy). The thin clouds of glass then fluoresced like a krypton sign or a Scooby-Doo ghost.
Thanks Brian May and Hanny! This is one fancy voorwerp.
Today I am posting some pictures of what I think is the most beautiful deep space object. The Sombrero Galaxy (M104) is a nearby galaxy which is visible edge-on in the constellation of Virgo. Actually, calling it an object might be a bit misleading since M104 consists of more than 400 billion stars–not to mention numerous associated globular clusters, innumerable planets, immense clouds of gas & gas, and a supermassive black hole which lies in the center. The black hole in the center of M104 isn’t a mild mannered & quiescent black hole like the one in the center of the Milky Way either. Based on the speed of revolution of the stars near the middle of M104, astronomers calculate that the central black hole has a billion times the mass of the sun.
In cosmic terms, the Sombrero galaxy is nearby—which is to say it is merely 28-odd million light years away. The galaxy was discovered in the late eighteenth century by Pierre Méchain . Other prominent 18th century astronomers subsequently observed and studied M104, including Charles Messier (which is the reason the galaxy is included in the “Messier” catalog and has a M-designation) and the redoubtable William Herschel who noted a “dark-stratum” bounding the luminous central bulge. We now know that this ring around M104 is a toroid dust lane of vast proportions which halos the galaxy. Astronomers initially thought that the Sombrero Galaxy was an unbarred spiral galaxy, but thanks to observations from NASA’s Spitzer space telescope (an infrared scope orbiting Earth), the scientific community has revised their estimation of its size upward. It lies somewhere between a spiral galaxy and an elliptical galaxy. In other words, when you look at the Sombrero Galaxy, you are looking at something vast beyond human comprehension—a galaxy bigger than our own filled with who knows what things we will never know. And yet if you expand the Hubble photo at the top of this post, you will see that all of the little stars shining around M104 are other galaxies farther away.
One of life’s disappointments is the dearth of fine art concerning outer space. Outer space is vast beyond imagining: it contains everything known. Indeed, we live in space (albeit on a little blue planet hurtling around an obscure yellow star)–but cosmic wonders do not seem to have called out to the greatest artists of the past as much as religious or earthly subjects. There are of course many commercial illustrations featuring the elements of science fiction: starships, ringed planets, exploding suns, and tentacled aliens (all of which I like) and there are also didactic scientific illustrations, which attempt to show binary stars, ring galaxies, quasars and other celestial subjects. Yet only rarely does a fine artist turn his eyes towards the heavens, and it is even less frequent that such a work captures the magnificence and enormity of astronomy.
Fortunately the Dutch artist MC Escher was such an artist. His space-themed engravings utilize religious, architectural, and biological elements in order to give a sense of scale and mystery. The familiar architecture and subjects are transcended and eclipsed by the enormity of the cosmic subjects. Here are two of his woodcuts which directly concern outer space.
The first print is a wood engraving entitled The Dream (Mantis Religiosa) shows a fallen bishop stretched on a catafalque as a huge otherworldly praying mantis stands on his chest (the whole work is a sort of pun on the mantis’ taxonomical name Mantis religiosa “the religious mantis”. The buildings arround the bishop and the bug are dissipating to reveal the wonders of the night sky. The bishop’s world of religious mysteries and social control are vanishing in the face of his death. Greater mysteries are coming to life and beckoning the anxious viewer.
The colored woodcut “Other World” shows a simurgh standing above, below and in front of the viewer in a spatially impossible gazebo on an alien world. The simurgh is a mythical animal from ancient Persian literature and art which combines human and avian elements. Sufi mystics sometimes utilize the simurgh as a metaphor for the unknowable nature of divinity. Yet here the simurgh is dwarfed by the craters beneath him and by the planetary rings filling up the sky above. A strange horn hangs above, below, and to the side of the viewer. Perhaps it is a shofar from ancient Judea or a cornucopia from the great goat Amalthea. Whatever the case, the viewer has become unfixed in mathematical space and is simultaneously looking at the world from many different vantage points. A galaxy hangs in the sky above as a reminder of the viewer’s insignificance.
Above all it is Escher’s manipulation of spatial constructs within his art that makes the viewer realize the mathematical mysteries which we are daily enmeshed in. The multidimensional geometric oddities rendered by Escher’s steady hand in two dimensions characterize a universe which contains both order and mystery. Giant bugs and bird/human hybrids are only symbols of our quest to learn the underpinnings of the firmament. Escher’s art is one of the few places where science and art go together hand in hand as partners. This synthesis gives a lasting greatness to his artwork, which are undiminished by popularity and mass reproduction.
My apologies for the blogging break last week. Usually I try to write a new post every weekday, but last week was a blogging holiday. To reinvigorate things after the lost week, let’s turn to a big subject—in fact a super-massive subject! Long ago, Ferrebeekeeper featured a post about Eta Carinae, a blue hypergiant with a hundred times the mass of the sun (which is itself a million times more massive than Earth). Stars like Eta Carinae are rarely formed and short lived—there are probably less than a dozen in our galaxy. However compared to the most massive object in the galaxy, Eta Carinae is puny and common. Twenty six thousand light years away from the solar system there exists a truly monstrous space object!
In 1974, Astronomers discovered an astronomical feature which was emitting exotic radio waves in the Sagittarius constellation. The scientists named the feature “Sagittarius A” and set out to determine what it was. Part of the feature seems to be the remnants of a star which had gone supernova. A second part of the feature is a cloud of ionized gas surrounded by an even larger torus of molecular gas. In the middle of Sagittarius A is something which is emitting most of the high energy electromagnetic radiation visible to radio telescopes. The cloud of ionized gas seems to be emptying into it and nearby stars orbit it with greater velocity than stars move anywhere else in the galaxy (in fact the object affects the proper motion of thousands of nearby stars). And yet the space object at the center of Sagittarius A has a diameter of only 44 million kilometers–a bit less than the distance between the middle of the sun and Mercury at its perihelion (when the rocky planet is closest to the sun). By calculating the proper motion of thousands of nearby stars, scientists determined that the mysterious object at the center of Sagittarius A (which they took to calling Sagitarrius A*) has mass of 4.31 million suns (i.e. solar masses). Whatever lies at the center of Sagittarius A–which I probably should have mentioned, is also the center of the Milky Way Galaxy–is smaller in volume than a large star, but has a mass which exceeds by many orders of magnitude even exotic hypergiants like Eta Carina.
Of course the only kinds of discrete objects which we know (or even hypothesize) to be capable of attaining such mass are black holes. It is believed that most (indeed probably all) galaxies have super-massive black hole at their centers. Smaller galaxies have small super massive black holes (forgive the oxymoron) but large galaxies have immense central black holes which can equal billions of solar masses. Radio astronomers have observed plumes of exotic electromagnetic radiation coming from the center of other galaxies, and they wondered where the Milky Way’s galactic center was located. It seems that a supernova near the galactic center blew away a great deal of the dust and gas on which the black hole would otherwise “feed” thereby making the galactic center of the Milky Way less energetic than the active center of farther (e.g. older) galaxies.
The super massive black holes which lie at the center of galaxies may be a result of the accretion of matter around stellar-sized black holes (which could grow quickly in matter-rich galactic cores) but most astrophysicists believe they are instead a primordial feature of the Big Bang around which galaxies themselves coalesced. The ultimate nature of super massive black holes remains unknown and seems to be tied to the nature and shape of our universe.