Astronomy and Stars
Discussions about astronomy and stars. As we look further out what can we find in the universe beyond Earth's atmosphere?
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All stars are not created equal. They can vary in mass by over a factor of 1,000. Our sun is classified as a diminutive yellow dwarf. What's more, stars are not born in isolation, but inside giant molecular clouds of hydrogen. The question has been: what fraction of stars precipitate out of these clouds into clusters that contain blue giants, yellow dwarfs, and red dwarfs? It's like asking if all automobile manufacturers fabricate the same proportion of trucks, SUVs, sedans, and subcompacts. The best way to address the question is not to look around our Milky Way – which we are inside – but far out into space to the neighboring Andromeda galaxy, 2.5 million light-years aw…
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Quasars are the light fantastic. These brilliant cores of active galaxies blaze with the radiance of a hundred billion stars compressed into a region of space not much larger than our solar system. Supermassive black holes, with millions or billions of times the mass of our sun, are the only imaginable powerhouse behind these tsunamis of raw energy. Hubble Space Telescope astronomers set their sights on the nearest quasar to Earth, Markarian 231, located 581 million light-years away. Black holes – even supermassive ones – are too compact to be resolved by any present-day telescope. So, astronomers did the next best thing, measure all the light from a disk of infalling m…
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A team of astronomers, including half a dozen from the Space Telescope Science Institute (STScI) in Baltimore, Maryland, have used the Gemini Observatory's new Gemini Planet Imager to find the most solar system-like planet ever directly imaged around another star. The planet, known as 51 Eridani b, is about two times the mass of Jupiter and orbits its host star at about 13 times the Earth-sun distance (equivalent to being between Saturn and Uranus in our solar system). The planet is located about 100 light-years away from Earth. The Gemini data provide scientists with the strongest-ever spectroscopic detection of methane in the atmosphere of an extrasolar planet, adding t…
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What happens when you find something in the wrong place at the wrong time? That's a question astronomers have been trying to answer after finding several exploding stars outside the cozy confines of galaxies, where most stars reside. These wayward supernovae also have puzzled astronomers because they exploded billions of years before their predicted detonations. Astronomers using archived observations from several telescopes, including the Hubble Space Telescope, have developed a theory for where these doomed stars come from and how they arrived at their current homes. According to their scenario, the supernovae were once stars in double-star systems that wandered too c…
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Astronomers have long wondered how the universe's largest elliptical galaxies continue making stars long after their peak years of star birth. By combining data from NASA's Hubble Space Telescope with observations from a suite of ground-based and space telescopes, two independent teams have uncovered a unique process to explain how this star birth continues. The teams found that that the galaxy's central black hole, jets, and newborn stars are all parts of a self-regulating cycle. In that cycle, jets shooting out of the galaxy's center heat a halo of surrounding gas, controlling the rate at which it cools and falls into the galaxy. The astronomers used Hubble's high resol…
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The majority of planets discovered outside our solar system orbit close to their parent stars because these planets are the easiest to find. But to fully understand how distant planetary systems are put together, astronomers must conduct a census of all the planets around a star. So they need to look farther away from the star-from about the distance of Jupiter is from our sun, and beyond. Now, astronomers using NASA's Hubble Space Telescope and the W. M. Keck Observatory in Hawaii have confirmed the existence of a Uranus-sized exoplanet orbiting far from its central star, discovered through a technique called gravitational microlensing. Microlensing occurs when a foreg…
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Astronomers using NASA's Hubble Space Telescope have discovered an immense cloud of hydrogen dubbed "The Behemoth" bleeding off a planet orbiting a nearby star. The enormous, comet-like feature is about 50 times the size of the parent star. The hydrogen is evaporating from a warm, Neptune-sized planet, due to extreme radiation from the star. A phenomenon this large has never before been seen around any exoplanet. It may offer clues to how Super-Earths – massive, rocky, versions of Earth – are born around other stars through the evaporation of their outer layers of hydrogen. Finding "The Behemoth" could be a game-changer for characterizing atmospheres of the whole populati…
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Quasars are the light fantastic. They are the brightest beacons in the universe, blazing across space with the intrinsic brightness of one trillion suns. Yet the objects are not vast galaxies, but they appear as pinpoint sources in the biggest telescopes of today – hence the term "quasar" for quasi-stellar object. Discovered in the 1960s, it took more than two decades of research to come to the conclusion that quasars are produced by the gusher of energy coming from over-fed supermassive black holes inside the cores of very distant galaxies. And, most quasars bloomed into a brief existence 12 billion years ago. The big question has been, why? What was happening in the u…
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Researchers using NASA's Hubble Space Telescope have detected a stratosphere and temperature inversion in the atmosphere of a planet several times the mass of Jupiter, called WASP-33b. Earth's stratosphere sits above the troposphere, the turbulent, active-weather region that reaches from the ground to the altitude where nearly all clouds top out. In the troposphere, the temperature is warmer at the bottom – ground level – and cools down at higher altitudes. The stratosphere is just the opposite: There, the temperature rises at higher altitudes. This is called a temperature inversion, and it happens because ozone in the stratosphere absorbs some of the sun's radiation, pre…
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This magnificent spiral galaxy is at the edge of what astronomers call the Local Void. The Local Void is a huge volume of space that is at least 150 million light-years across that doesn't seen to contain anything much. There are no obvious galaxies. This void is simply part of the structure of the universe where matter grows clumpy over time so that galaxies form clusters and chains, which are separated by regions mostly devoid of galaxies. This results in sort of a "soap bubble" structure on large scales. The galaxy, as photographed by NASA's Hubble Space Telescope, is especially colorful where bright red patches of gas can be seen scattered through its spiral arms. Bri…
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Two of the most reliable changes in the sky are the daily rising of the sun in the east and setting of the sun in the west. But if you lived on a couple of Pluto's moons you wouldn't know when the day would begin, or even what direction the sun would rise. That's because, unlike Earth's moon, at least two of Pluto's small moons, Hydra and Nix, are tumbling chaotically through space. Why? Because they orbit inside a dynamically shifting gravitational field caused by the system's two central bodies, Pluto and Charon, that are whirling around each other. The moons are also football shaped, and this contributes to the chaotic rotation. By contrast, Earth's moon keeps the sa…
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One of the trademarks of the Star Wars film episodes is the dreaded Death Star battle station that fires a beam of directed energy powerful enough to blow up planets. The real universe has such fireworks, and they are vastly more powerful than the Star Wars creation. These extragalactic jets are tearing across hundreds of light-years of space at 98 percent the speed of light. Instead of a battle station, the source of the killer beam is a supermassive black hole weighing many million or even a billion times the mass of our sun. Energy from the spinning black hole, and its titanic magnetic fields, shape a narrow jet of gas blasting out a galaxy's center. Hubble has been us…
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Astronomers have spent decades trying to determine the oddball behavior of an aging star nicknamed "Nasty 1" residing in our Milky Way galaxy. Nasty 1 was identified as a Wolf-Rayet star, a rapidly evolving star that is much more massive than our sun. The star loses its hydrogen-filled outer layers quickly, exposing its super-hot and extremely bright helium-burning core. But Nasty 1 doesn't look like a typical Wolf-Rayet star. Astronomers using NASA's Hubble Space Telescope had expected to see a bipolar outflow of twin lobes of gas from the star, perhaps similar to those emanating from the massive star Eta Carinae. The astronomers were surprised, however, to find a panc…
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Globular star clusters are isolated star cities, home to hundreds of thousands of stars. And like the fast pace of cities, there's plenty of action in these stellar metropolises. The stars are in constant motion, orbiting around the cluster's center. Past observations have shown that the heavyweight stars live in the crowded downtown, or core, and lightweight stars reside in the less populated suburbs. But as heavyweight stars age, they rapidly lose mass, cool down, and shut off their nuclear furnaces. After the purge, only the stars' bright, super-hot cores remain, and they are called white dwarfs. This weight-loss program causes the now lighter-weight white dwarfs to …
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The Andromeda galaxy is our Milky Way's nearest neighbor in space. The majestic spiral of over 100 billion stars is comparable in size to our home galaxy. At a distance of 2.5 million light-years, it is so close to us the galaxy can be seen as a cigar-shaped smudge of light high in the autumn sky. But if you could see the huge bubble of hot, diffuse plasma surrounding it, it would appear 100 times the angular diameter of the full Moon! The gargantuan halo is estimated to contain half the mass of the stars in the Andromeda galaxy itself. It can be thought of as the "atmosphere" of a galaxy. Astronomers using Hubble identified the gas in Andromeda's halo by measuring how it…
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The universe is incredibly big. But how do astronomers know that? Billion-mile-long tape measures can't be found at the hardware store. Instead, astronomers use the expansion of the universe itself to establish milepost markers. The light from remote objects is attenuated and weakened as space stretches like a rubber band. The consequences are that starlight will look redder relative to a nearby star of the same temperature. When starlight is spread into its component color via spectroscopy, features in the light will be shifted to the red end of the spectrum. This "redshift" can be used to reliably calibrate distances. The challenge is the farthest objects in the univers…
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NASA and ESA are celebrating the Hubble Space Telescope's silver anniversary of 25 years in space by unveiling some of nature's own fireworks – a giant cluster of about 3,000 stars called Westerlund 2. The cluster resides inside a vibrant stellar breeding ground known as Gum 29, located 20,000 light-years away in the constellation Carina. The comparatively young, 2-million-year-old star cluster contains some of our galaxy's hottest, brightest, and most massive stars. The largest stars are unleashing a torrent of ultraviolet light and hurricane-force winds that etch away the enveloping hydrogen gas cloud. This creates a fantasy celestial landscape of pillars, ridges, and v…
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Our Sun missed the stellar "baby boom" that erupted in our young Milky Way galaxy 10 billion years ago. During that time the Milky Way was churning out stars 30 times faster than it does today. Our galaxy was ablaze with a firestorm of star birth as its rich reservoir of hydrogen gas compressed under gravity, creating myriad stars. But our Sun was not one of them. It was a late "boomer," arising 5 billion years later, when star birth had plunged to a trickle. Astronomers compiled this story of our Milky Way's growth from studying galaxies similar in mass to our galaxy, found in deep surveys of the universe. Stretching back in time more than 10 billion years, the census …
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NASA and the Space Telescope Science Institute (STScI) have announced the selection of 17 new Hubble Fellows. STScI in Baltimore, Maryland, administers the Hubble Fellowship Program for NASA. The Hubble Fellowship Program includes all research relevant to present and future missions relating to NASA's Cosmic Origins Program. These missions currently include the Herschel Space Observatory, the Hubble Space Telescope (HST), the James Webb Space Telescope, the Stratospheric Observatory for Infrared Astronomy (SOFIA), and the Spitzer Space Telescope. The new Hubble Fellows will begin their programs in the fall of 2015. View the full article
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In 2007, Dutch schoolteacher Hanny van Arkel discovered a never-before-seen ghostly structure near a galaxy, while she was participating in an online amateur scientist project called Galaxy Zoo. The galaxy hosts a bright quasar that may have illuminated the apparition by hitting it with a beam of light from hot gas around a central black hole. Astronomers eagerly used the Hubble Space Telescope to do follow-up observations, which revealed knots of dust and gas in the "greenish blob." Assuming that this feature could offer insights into the puzzling behavior of active galaxies, Bill Keel of the University of Alabama, Tuscaloosa, initiated a search for other similar phenome…
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In particle physics labs, like the Large Hadron Collider in Geneva, Switzerland, scientists smash atoms together to study the underpinnings of matter and energy. On the scale of the macrocosm, nature provides a similar experiment by crashing clusters of galaxies together. Besides galaxies and gas, the galaxy clusters contain huge amounts of dark matter. Dark matter is a transparent form of matter that makes up most of the mass in the universe. During collisions, the clouds of gas enveloping the galaxies crash into each other and slow down or stop. Astronomers found that the dark matter continued straight through the violent collisions, without slowing down relative to the…
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Astronomers at the Space Telescope Science Institute and the Johns Hopkins University, both in Baltimore, Maryland, have created a new master catalog of astronomical objects called the Hubble Source Catalog. The catalog provides one-stop shopping for measurements of objects observed with NASA's Hubble Space Telescope. Hubble has amassed a rich legacy of images and other scientific data over its 25 years of exploring the universe. All of the images are stored in the computer-based Barbara A. Mikulski Archive for Space Telescopes (MAST), which astronomers use for their research. The archive is bursting with more than a million images, which contain roughly 100 million sma…
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Nearly 500 million miles from the Sun lies a moon orbiting Jupiter that is slightly larger than the planet Mercury and may contain more water than all of Earth's oceans. Temperatures are so cold, though, that water on the surface freezes as hard as rock and the ocean lies roughly 100 miles below the crust. Nevertheless, where there is water there could be life as we know it. Identifying liquid water on other worlds — big or small — is crucial in the search for habitable planets beyond Earth. Though the presence of an ocean on Ganymede has been long predicted based on theoretical models, NASA's Hubble Space Telescope found the best evidence for it. Hubble was used to watch…
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Three-leaf clover plants abound everywhere: on lawns, in gardens, and in forests. But spotting a four-leaf clover is a rare, lucky find. Astronomers using the Hubble Space Telescope have found the equivalent of a four-leaf clover with the discovery of four images of the same supernova. The images are arranged around a giant foreground elliptical galaxy embedded in a cluster of galaxies. The arrangement forms a cross-shaped pattern called an Einstein Cross. The powerful gravity from both the elliptical galaxy and its galaxy cluster magnifies the light from the supernova behind them in an effect called gravitational lensing. The elliptical galaxy and its galaxy cluster, MAC…
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Over a decade before planets were found orbiting normal stars, the astronomy world was intrigued by the discovery of a vast, edge-on, pancake-flat disk of dust and gas encircling the newborn star Beta Pictoris. It appeared to validate the hypothesis by the German philosopher Immanuel Kant, 230 years ago, that our solar system was born when planets condensed from nebular material in the plane of such a disk. (This model was independently proposed by French scholar Pierre-Simon Laplace in 1796.) Kant regarded the coplanar obits of the planets a fossil skeleton of the long-ago disintegrated disk. Though nearly two dozen circumstellar debris disks have been viewed by the Hubb…
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