Arp 273 is a group of galaxies which interact with each other. The constellation is 300 million light years away from Earth in the constellation Andromeda. The Andromeda galaxy is also located in the Andromeda constellation. The larger of th...
Tag: andromeda galaxy (page 1 of 2)
Excerpt from hubblesite.org
Scientists using NASA's Hubble Space Telescope have discovered that the immense halo of gas enveloping the Andromeda galaxy, our nearest massive galactic neighbor, is about six times larger and 1,000 times more massive than previously measured. The dark, nearly invisible halo stretches about a million light-years from its host galaxy, halfway to our own Milky Way galaxy. This finding promises to tell astronomers more about the evolution and structure of majestic giant spirals, one of the most common types of galaxies in the universe.
"Halos are the gaseous atmospheres of galaxies. The properties of these gaseous halos control the rate at which stars form in galaxies according to models of galaxy formation," explained the lead investigator, Nicolas Lehner of the University of Notre Dame, Indiana. The gargantuan halo is estimated to contain half the mass of the stars in the Andromeda galaxy itself, in the form of a hot, diffuse gas. If it could be viewed with the naked eye, the halo would be 100 times the diameter of the full Moon in the sky. This is equivalent to the patch of sky covered by two basketballs held at arm's length.
The Andromeda galaxy, also known as M31, lies 2.5 million light-years away and looks like a faint spindle, about 6 times the diameter of the full Moon. It is considered a near-twin to the Milky Way galaxy.
Because the gas in Andromeda's halo is dark, the team looked at bright background objects through the gas and observed how the light changed. This is a bit like looking at a glowing light at the bottom of a pool at night. The ideal background "lights" for such a study are quasars, which are very distant bright cores of active galaxies powered by black holes. The team used 18 quasars residing far behind Andromeda to probe how material is distributed well beyond the visible disk of the galaxy. Their findings were published in the May 10, 2015, edition of The Astrophysical Journal.
Earlier research from Hubble's Cosmic Origins Spectrograph (COS)-Halos program studied 44 distant galaxies and found halos like Andromeda's, but never before has such a massive halo been seen in a neighboring galaxy. Because the previously studied galaxies were much farther away, they appeared much smaller on the sky. Only one quasar could be detected behind each faraway galaxy, providing only one light anchor point to map their halo size and structure. With its close proximity to Earth and its correspondingly large footprint on the sky, Andromeda provides a far more extensive sampling of a lot of background quasars.
"As the light from the quasars travels toward Hubble, the halo's gas will absorb some of that light and make the quasar appear a little darker in just a very small wavelength range," explains co-investigator J. Christopher Howk, also of Notre Dame. "By measuring the dip in brightness in that range, we can tell how much halo gas from M31 there is between us and that quasar."
The scientists used Hubble's unique capability to study the ultraviolet light from the quasars. Ultraviolet light is absorbed by Earth's atmosphere, which makes it difficult to observe with a ground-based telescope. The team drew from about 5 years' worth of observations stored in the Hubble data archive to conduct this research. Many previous Hubble campaigns have used quasars to study gas much farther away than — but in the general direction of — Andromeda, so a treasure trove of data already existed.
But where did the giant halo come from? Large-scale simulations of galaxies suggest that the halo formed at the same time as the rest of Andromeda. The team also determined that it is enriched in elements much heavier than hydrogen and helium, and the only way to get these heavy elements is from exploding stars called supernovae. The supernovae erupt in Andromeda's star-filled disk and violently blow these heavier elements far out into space. Over Andromeda's lifetime, nearly half of all the heavy elements made by its stars have been expelled far beyond the galaxy's 200,000-light-year-diameter stellar disk.
What does this mean for our own galaxy? Because we live inside the Milky Way, scientists cannot determine whether or not such an equally massive and extended halo exists around our galaxy. It's a case of not being able to see the forest for the trees. If the Milky Way does possess a similarly huge halo, the two galaxies' halos may be nearly touching already and quiescently merging long before the two massive galaxies collide. Hubble observations indicate that the Andromeda and Milky Way galaxies will merge to form a giant elliptical galaxy beginning about 4 billion years from now.
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The Hooker 100-inch reflecting telescope at the Mount Wilson Observatory, just outside Los Angeles. Edwin Hubble's chair, on an elevating platform, is visible at left. A view from this scope first told Hubble our galaxy isn't the only one. Courtesy of The Observatories of the Carnegie Institution for Science Collection at the Huntington Library, San Marino, Calif. |
Excerpt from hnpr.org
The Hubble Space Telescope this week celebrates 25 years in Earth's orbit. In that time the telescope has studied distant galaxies, star nurseries, planets in our solar system and planets orbiting other stars.
But, even with all that, you could argue that the astronomer for whom the telescope is named made even more important discoveries — with far less sophisticated equipment.
A young Edwin Hubble at Mount Wilson's 100-inch telescope circa 1922, ready to make history.
Edwin Hubble Papers/Courtesy of Huntington Library, San Marino, Calif.
In the 1920s, Edwin Hubble was working with the 100-inch Hooker telescope on Mount Wilson, just outside Los Angeles. At the time, it was the largest telescope in the world.
On a chilly evening, I climb up to the dome of that telescope with operator Nik Arkimovich and ask him to show me where Hubble would sit when he was using the telescope. Arkimovich points to a platform near the top of the telescope frame.
"He's got an eyepiece with crosshairs on it," Arkimovich explains. The telescope has gears and motors that let it track a star as it moves across the sky. "He's got a paddle that allows him to make minor adjustments. And his job is to keep the star in the crosshairs for maybe eight hours."
"It's certainly much, much easier today," says John Mulchaey, acting director of the observatories at Carnegie Institution of Science. "Now we sit in control rooms. The telescopes operate brilliantly on their own, so we don't have to worry about tracking and things like this."
The headquarters of the Carnegie observatories is at the foot of Mount Wilson, in the city of Pasadena. It's where Hubble worked during the day.
A century's worth of plates are stored here in the basement. Mulchaey opens a large steel door and ushers me into a room filled with dozens of file cabinets.
"Why don't we go take a look at Hubble's famous Andromeda plates," Mulchaey suggests.
The plates are famous for a reason: They completely changed our view of the universe. Mulchaey points to a plate mounted on a light stand.
"This is a rare treat for you," he says. "This plate doesn't see the light of day very often."
This glass side of a photographic plate shows where Hubble marked novas. The red VAR! in the upper right corner marks his discovery of the first Cepheid variable star — a star that told him the Andromeda galaxy isn't part of our Milky Way.
Courtesy of the Carnegie Observatories
The plate shows the spiral shape of the Andromeda galaxy. Hubble was looking for exploding stars called novas in Andromeda. Hubble marked these on the plate with the letter "N."
"The really interesting thing here," Mulchaey says, "is there's one with the N crossed out in red — and he's changed the N to VAR with an exclamation point."
Hubble had realized that what he was seeing wasn't a nova. VAR stands for a type of star known as a Cepheid variable. It's a kind of star that allows you to make an accurate determination of how far away something is. This Cepheid variable showed that the Andromeda galaxy isn't a part of our galaxy.
At the time, most people thought the Milky Way was it — the only galaxy in existence.
"And what this really shows is that the universe is much, much bigger than anybody realizes," Mulchaey says.
It was another blow to our human conceit that we are the center of the universe.
Hubble went on to use the Mount Wilson telescope to show the universe was expanding, a discovery so astonishing that Hubble had a hard time believing it himself.
If Hubble could make such important discoveries with century-old equipment, it makes you wonder what he might have turned up if he'd had a chance to use the space telescope that bears his name.
Excerpt from qz.com
The vastness of space is so expansive, so inconceivable, that frankly, it makes humanity’s lot in the universe seem pretty tiny and pointless.
Amplifying that sense of insignificance, NASA has released its largest, most detailed image of space ever. Taken by the Hubble Space Telescope, it captures the Andromeda Galaxy, one of our nearest galactic neighbors at a mere 2.5 million light years away.
The full size image is about 60,000 by 22,000 pixels, a total of 1.5 billion pixels. That’s about 1,000 times the resolution of regular high-definition. It is detailed enough that the telescope can resolve individual stars in the 61,000 light year-long slice of galaxy captured by the image—”like photographing a beach and resolving individual grains of sand,” according to NASA. All in all, there are over 100 million stars in the photo. (See video)
And indeed, zooming in on the image does make it look like a close-up of a beach:
Click to zoom
Watch how our closest neighbor galaxy begins to appear from our front porch. Click to zoom
Excerpt from earthsky.org
Admit it. You’ve probably got a pair of binoculars lying around your house somewhere. They may be perfect – that’s right, perfect – for beginning stargazing. Follow the links below to learn more about the best deal around for people who want to get acquainted with the night sky: a pair of ordinary binoculars.
1. Binoculars are a better place to start than telescopes
2. Start with a small, easy-to-use size
3. First, view the moon with binoculars.
4. Move on to viewing planets with binoculars.
5. Use your binoculars to explore inside our Milky Way.
6. Use your binoculars to peer beyond the Milky Way.
1. Binoculars are a better place to start than telescopes. The fact is that most people who think they want to buy a telescope would be better off using binoculars for a year or so instead. That’s because first-time telescope users often find themselves completely confused – and ultimately put off – by the dual tasks of learning the use a complicated piece of equipment (the ‘scope) while at the same time learning to navigate an unknown realm (the night sky).
Beginning stargazers often find that an ordinary pair of binoculars – available from any discount store – can give them the experience they’re looking for. After all, in astronomy, magnification and light-gathering power let you see more of what’s up there. Even a moderate form of power, like those provided by a pair of 7×50 binoculars, reveals 7 times as much information as the unaided eye can see.
You also need to know where to look. Many people start with a planisphere as they begin their journey making friends with the stars. You can purchase a planisphere at the EarthSky store. Also consider our Astronomy Kit, which has a booklet on what you can see with your binoculars.
2. Start with a small, easy-to-use size. Don’t buy a huge pair of binoculars to start with! Unless you mount them on a tripod, they’ll shake and make your view of the heavens shakey, too. The video above – from ExpertVillage – does a good job summing up what you want. And in case you don’t want to watch the video, the answer is that 7X50 binoculars are optimum for budding astronomers. You can see a lot, and you can hold them steadily enough that jitters don’t spoil your view of the sky. Plus they’re very useful for daylight pursuits, like birdwatching. If 7X50s are too big for you – or if you want binoculars for a child – try 7X35s.
February 24, 2014 moon with earthshine by Greg Diesel Landscape Photography.
You’ll want to start your moon-gazing when the moon is just past new – and visible as a waxing crescent in the western sky after sunset. At such times, you’ll have a beautiful view of earthshine on the moon. This eerie glow on the moon’s darkened portion is really light reflected from Earth onto the moon’s surface. Be sure to turn your binoculars on the moon at these times to enhance the view.
Each month, as the moon goes through its regular phases, you can see the line of sunrise and sunset on the moon progress across the moon’s face. That’s just the line between light and dark on the moon. This line between the day and night sides of the moon is called the terminator line. The best place to look at the moon from Earth – using your binoculars – is along the terminator line. The sun angle is very low in this twilight zone, just as the sun is low in our sky around earthly twilight. So, along the terminator on the moon, lunar features cast long shadows in sharp relief.
You can also look in on the gray blotches on the moon called maria, named when early astronomers thought these lunar features were seas. The maria are not seas, of course, and instead they’re now thought to have formed 3.5 billion years ago when asteroid-sized rocks hit the moon so hard that lava percolated up through cracks in the lunar crust and flooded the impact basins. These lava plains cooled and eventually formed the gray seas we see today.
The white highlands, nestled between the maria, are older terrain pockmarked by thousands of craters that formed over the eons. Some of the larger craters are visible in binoculars. One of them, Tycho, at the six o’clock position on the moon, emanates long swatches of white rays for hundreds of miles over the adjacent highlands. This is material kicked out during the Tycho impact 2.5 million years ago.
Photo of Jupiter’s moons by Earthsky Facebook friend Carl Galloway. Thank you Carl! The four major moons of Jupiter are called Io, Europa, Ganymede and Callisto. This is a telescopic view, but you can glimpse one, two or more moons through your binoculars, too.
4. Move on to viewing planets with binoculars. Here’s the deal about planets. They move around, apart from the fixed stars. They are wanderers, right?
You can use our EarthSky Tonight page to locate planets visible around now. Notice if any planets are mentioned in the calendar on the Tonight page, and if so click on that day’s link. On our Tonight page, we feature planets on days when they’re easily identifiable for some reason – for example, when a planet is near the moon. So our Tonight page calendar can help you come to know the planets, and, as you’re learning to identify them, keep your binoculars very handy. Binoculars will enhance your view of a planet near the moon, for example, or two planets near each other in the twilight sky. They add a lot to the fun!
Below, you’ll find some more simple ideas on how to view planets with your binoculars.
Mercury and Venus. These are both inner planets. They orbit the sun closer than Earth’s orbit. And for that reason, both Mercury and Venus show phases as seen from Earth at certain times in their orbit – a few days before or after the planet passes between the sun and Earth. At such times, turn your binoculars on Mercury or Venus. Good optical quality helps here, but you should be able to see them in a crescent phase. Tip: Venus is so bright that its glare will overwhelm the view. Try looking in twilight instead of true darkness.
Mars. Mars – the Red Planet – really does look red, and using binoculars will intensify the color of this object (or of any colored star). Mars also moves rapidly in front of the stars, and it’s fun to aim your binoculars in its direction when it’s passing near another bright star or planet.
Jupiter. Now on to the real action! Jupiter is a great binocular target, even for beginners. If you are sure to hold your binoculars steadily as you peer at this bright planet, you should see four bright points of light near it. These are the Galilean Satellites – four moons gleaned through one of the first telescopes ever made, by the Italian astronomer Galileo. Note how their relative positions change from night to night as each moon moves around Jupiter in its own orbit.
Saturn.Although a small telescope is needed to see Saturn’s rings, you can use your binoculars to see Saturn’s beautiful golden color. Experienced observers sometimes glimpse Saturn’s largest moon Titan with binoculars. Also, good-quality high-powered binoculars – mounted on a tripod – will show you that Saturn is not round. The rings give it an elliptical shape.
Uranus and Neptune. Some planets are squarely binocular and telescope targets. If you’re armed with a finder chart, two of them, Uranus and Neptune, are easy to spot in binoculars. Uranus might even look greenish, thanks to methane in the planet’s atmosphere. Once a year, Uranus is barely bright enough to glimpse with the unaided eye . . . use binoculars to find it first. Distant Neptune will always look like a star, even though it has an atmosphere practically identical to Uranus.
There are still other denizens of the solar system you can capture through binocs. Look for the occasional comet, which appears as a fuzzy blob of light. Then there are the asteroids – fully 12 of them can be followed with binoculars when they are at their brightest. Because an asteroid looks star-like, the secret to confirming its presence is to sketch a star field through which it’s passing. Do this over subsequent nights; the star that changes position relative to the others is our solar system interloper.
Pleiades star cluster, also known as the Seven Sisters
5. Use your binoculars to explore inside our Milky Way. Binoculars can introduce you to many members of our home galaxy. A good place to start is with star clusters that are close to Earth. They cover a larger area of the sky than other, more distant clusters usually glimpsed through a telescope.
Beginning each autumn and into the spring, look for a tiny dipper-like cluster of stars called the Pleiades. The cluster – sometimes also called the Seven Sisters – is noticeable for being small yet distinctively dipper-like. While most people say they see only six stars here with the unaided eye, binoculars reveal many more stars, plus a dainty chain of stars extending off to one side. The Pleiades star cluster is looks big and distinctive because it’s relatively close – about 400 light years from Earth. This dipper-shaped cluster is a true cluster of stars in space. Its members were born around the same time and are still bound by gravity. These stars are very young, on the order of 20 million years old, in contrast to the roughly five billion years for our sun.
Stars in a cluster all formed from the same gas cloud. You can also see what the Pleiades might have like in a primordial state, by shifting your gaze to the prominent constellation Orion the Hunter. Look for Orion’s sword stars, just below his prominent belt stars. If the night is crisp and clear, and you’re away from urban streetlight glare, unaided eyes will show that the sword isn’t entirely composed of stars. Binoculars show a steady patch of glowing gas where, right at this moment, a star cluster is being born. It’s called the Orion Nebula. A summertime counterpart is the Lagoon Nebula, in Sagittarius the Archer.
With star factories like the Orion Nebula, we aren’t really seeing the young stars themselves. They are buried deep within the nebula, bathing the gas cloud with ultraviolet radiation and making it glow. In a few tens of thousands of years, stellar winds from these young, energetic stars will blow away their gaseous cocoons to reveal a newly minted star cluster.
Scan along the Milky Way to see still more sights that hint at our home galaxy’s complexity. First, there’s the Milky Way glow itself; just a casual glance through binoculars will reveal that it is still more stars we can’t resolve with our eyes . . . hundreds of thousands of them. Periodically, while scanning, you might sweep past what appears to be blob-like, black voids in the stellar sheen. These are dark, non-glowing pockets of gas and dust that we see silhouetted against the stellar backdrop. This is the stuff of future star and solar systems, just waiting around to coalesce into new suns.
Andromeda Galaxy from Chris Levitan Photography.
Many people use the M- or W-shaped constellation Cassiopeia to find the Andromeda Galaxy. See how the star Schedar points to the galaxy?
It’s a whole other galaxy like our own, shining across the vastness of intergalactic space. Light from the Andromeda Galaxy has traveled so far that it’s taken more than 2 million years to reach us.
Two smaller companions visible through binoculars on a dark, transparent night are the Andromeda Galaxy’s version of our Milky Way’s Magellanic Clouds. These small, orbiting, irregularly-shaped galaxies that will eventually be torn apart by their parent galaxy’s gravity.
Such sights, from lunar wastelands to the glow of a nearby island universe, are all within reach of a pair of handheld optics, really small telescopes in their own right: your binoculars.
John Shibley wrote the original draft of this article, years ago, and we’ve been expanding it and updating it ever since. Thanks, John!
Bottom line: For beginning stargazers, there’s no better tool than an ordinary pair of binoculars. This post tells you why, explains what size to get, and gives you a rundown on some of the coolest binoculars sights out there: the moon, the planets, inside the Milky Way, and beyond. Have fun!
The Andromeda Galaxy
| This illustration shows the ESA's XMM-Newton space telescope. Using X-ray data collected by the telescope, scientists say they may have identified a dark-matter signal. (D. Ducros / European Space Agency) |
Excerpt from latimes.com
Scientists say they may have discovered a possible dark matter signal coded in the X-rays emanating from two bright objects in the sky.
The findings, set to be published next week in Physical Review Letters, could offer tangible evidence for the existence of dark matter -- and help researchers build new tools to search for and study this mysterious stuff.
When it comes to matter in the universe, dark matter is like a backroom political power broker: You never see it, but behind the scenes, it’s been throwing its weight around. The effects of its gravitational influence can be seen in the large-scale structures of the cosmos. Dark matter makes up about 84.5% of the matter in the universe while all the stuff we actually see -- stars, galaxies, planets, ourselves -- makes up the remaining 15.5%.* The enormous galaxies and clusters of galaxies that populate the universe are bantamweights compared to the massive, unseen dark matter ‘halos’ that anchor them.
Dark matter’s formidable gravitational influence is the only way that the strange stuff can be detected, because it’s invisible -- it does not interact with light. Physicists have no idea what it’s made of, although they’ve looked for it by building detectors in underground former gold mines, sending satellites into space and other methods.
But now, a team led by researchers at Leiden University in the Netherlands and the École Polytechnique Fédérale de Lausanne in Switzerland say they’ve discovered a signal that could be a sign of dark matter.
The scientists looked at X-ray emissions coming from the Andromeda galaxy and the Perseus galaxy cluster, collected by the European Space Agency’s XMM-Newton space telescope. After accounting for all the light particles (called photons) emanating from known sources in the Andromeda galaxy, they were left with a strange set of photons that had no known source. The found the same light signature emanating from the Perseus cluster. And when they turned their attention to the Milky Way, they found signs of this signal in our home galaxy, as well.
“It is consistent with the behavior of a line originating from the decay of dark matter particles,” the authors wrote in a pre-print of the study.
This weird light signal, they think, could be coming from the destruction of a hypothetical particle called a sterile neutrino (which, if it exists, might help explain dark matter). But it's going to take a lot of follow-up study to determine whether this signal is a scientific breakthrough or an anomalous blip.
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Galactic Federation Of Light The Andromeda Galaxy February 05 2012
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