Tag: astronomer (page 2 of 6)

Shortest Total Lunar Eclipse of the Century Visible Early Saturday

April 3, 2015 / / 0 Comments


 


Excerpt from space.com 
By Calia Cofield 

Don't forget to look skyward in the early hours of Saturday morning (April 4), to catch a glimpse of the shortest total lunar eclipse of the century.

The moon will be completely swallowed by Earth's shadow for just 4 minutes and 43 seconds on Saturday morning, according to NASA officials. During that time, the moon may change from its normal grayish hue to a deep, blood red. The total eclipse begins at 6:16 a.m. EDT (1016 GMT). You can watch a live webcast of the eclipse on the Slooh Observatory website, Slooh.com, or here at Space.com courtesy of Slooh, starting at 6 a.m. EDT (1000 GMT).
That color change can make for a dramatic display, especially for humans in the distant past, NASA officials said. 


"For early humans, [a lunar eclipse] was a time when they were concerned that life might end, because the moon became blood red and the light that the moon provided at night might have been taken away permanently," Mitzi Adams, an astronomer at NASA's Marshall Space Flight Center in Huntsville, Alabama, said during a news conference today (April 3). "But fortunately, [the light] always returned." 

The April 4 eclipse is the third in a series of four total lunar eclipses — known as a lunar tetrad — visible in the United States. Each of the eclipses is separated by about 6 months. The final installment of this four-eclipse series will occur on Sept. 28. Saturday's lunar eclipse follows closely behind the total solar eclipse that took place on March 20.

Earth's shadow has an outer ring, called the penumbra, and an inner core, called the umbra. Where the moon passes into the penumbra, it appears dark, as if a bite had been taken out of it. When the moon passes though the umbra, it turns a deep, red color.

A total lunar eclipse occurs when the moon is totally submerged in the umbra. On Saturday, the moon will begin to enter the umbra at about 6:16 a.m. EDT (1016 GMT) but will not be completely covered by the shadow until about 7:57 EDT (1157 GMT), after the moon has set in most locations east of the Mississippi River.

While the total eclipse will last less than five minutes, the moon will be partially submerged in the umbra for about one hour and 40 minutes. The dark shadow of the penumbra will first be visible on the moon's surface starting at about 5:35 a.m. EDT (0935 GMT), according to Sky and Telescope magazine.

Viewers west of the Mississippi River will be able to see the total lunar eclipse, starting at about 4:57 a.m. PDT (1157 GMT). Skywatchers in Hawaii and western Alaska will be able to watch the entire eclipse, from the moon's entrance to its exit from the penumbra.

Viewing Guide for Total Lunar Eclipse, April 4, 2015
This world maps shows the regions where the April 4 total lunar eclipse will be visible. The best viewing locations are in the Pacific Ocean.

This weekend's eclipse is extremely short because the moon is only passing through the outskirts of the umbra. (The shortest total lunar eclipse in recorded history, according to Adams, was in 1529 and lasted only 1 minute and 41 seconds).

The eclipse will not be visible in Europe or most of Africa. The partial eclipse will be visible in all except the easternmost parts of South America. The best viewing locations for the total eclipse will be in the Pacific region, including eastern Australia, New Zealand and other parts of Oceania.

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Hypatia, Ancient Alexandria’s Great Female Scholar

March 30, 2015 / / 0 Comments

An avowed paganist in a time of religious strife, Hypatia was also one of the first women to study math, astronomy and philosophy On the streets of Alexandria, Egypt, a mob led by Peter the Lector brutally murdered Hypatia, one of the last great thinkers of ancient Alexandria. (Mary Evans Picture Library / Alamy) By Sarah Zielinskismithsonian.com One day on the streets of Alexandria, Egypt, in the year 415 or 416, a mob of Christian zealots led by Peter the Lector accosted a wom [...]

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Earth’s address within a massive supercluster of 100,000 galaxies ~ Video

March 11, 2015 / / 0 Comments





Excerpt from cnet.com


Astronomers have mapped the Milky Way's position to the outskirts of a supercluster of galaxies, newly dubbed Laniakea, meaning "Immense Heaven".

The distribution of galaxies throughout the universe is not more-or-less even; instead, galaxies tend to cluster together, bound together by the pull of each other's gravity. These groups can be a variety of sizes. The Milky Way Galaxy, for instance, is part of what is called the Local Group, which contains upwards of 54 galaxies, covering a diameter of 10 megalight-years (10 million light-years).

Click to zoom

But this Local Group is just a small part of a much, much bigger structure, which researchers at the University of Hawai'i Mānoa have now mapped in detail. Coming in at over 100,000 galaxies, the massive supercluster has been given the name Laniakea -- "immense heaven" in Hawaiian.
The new 3D map was created by examining the positions and movements of the 8000 closest galaxies to the Milky Way. After calculating which galaxies were being pulled away from us and which were being pulled towards us -- accounting for the universe's expansion -- the team, led by astronomer R. Brent Tully, was able to map the paths of galactic migration -- and define the boundaries of Laniakea.

Traditionally, the borders of galactic superclusters have been difficult to map, but studying the gravitational force acting on our neighbouring galaxies has provided some important clues. All objects inside Laniakea are being slowly but surely drawn to a single point -- a force known as the Great Attractor, a gravitational anomaly with a mass tens of thousands of times the mass of the Milky Way.

Everything that is being pulled towards the Great Attractor is part of Laniakea -- although it's possible that Laniakea itself might in turn be part of a structure that is larger still.

"We probably need to measure to another factor of three in distance to explain our local motion," Tully said. "We might find that we have to come up with another name for something larger than we're a part of -- we're entertaining that as a real possibility."

The full paper, "The Laniakea supercluster of galaxies", can be read online in the journal Nature.

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Exoplanet Bonanza Boosts Count by 1,200

March 9, 2015 / / 0 Comments

Excerpt from news.discovery.comDozens of candidate worlds reside within the "habitable zones" of their parent stars. THE GIST - NASA's Kepler telescope has found more than 1,200 extrasolar planet candidates. - Smaller worlds, like Earth,...

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Far Flung Star Cluster Found at Milky Way’s Edge

March 8, 2015 / / 0 Comments

Astronomers in Brazil have discovered a cluster of stars forming at the edge of the Milky Way, according to a press release from the Royal Astronomical Society.




Excerpt from  news.discovery.com


This is unusual because it was believed that stars generally take form closer to the center of our spiral-shaped galaxy, rather than from its swirling, spiral arms, which are thousands of light-years away. These two clusters of stars — named Camargo 438 and 439 — were seen in a cloud at the galaxy’s outskirts.

Denilso Camargo, an astronomer at the Federal University of Rio Grande do Sul in Porto Alegre, Brazil, led a team that analyzed data from NASA’s orbiting Wide-Field Infrared Survey Explorer (WISE) observatory. They zeroed in on dense clumps of gas in so-called giant molecular clouds(GMCs) that are known to generate stars. GMCs are mainly located in the inner part of the galactic disc.

The new star clusters lie about 16,000 light-years away from the main disk of the Milky Way galaxy. How did they form there? The scientists aren’t yet sure but Camargo theorizes that one of two scenarios could have led to the stars’ formation.

In the first scenario, called the “chimney model,” supernovas could have flung the gas and dust that formed the cloud out of the Milky Way. Another explanation is the material could have drifted in from outside the galaxy.


“Our work shows that the space around the Galaxy is a lot less empty that we thought,” said Camargo. “The new clusters of stars are truly exotic.”

Camargo’s team published their results in the journal Monthly

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Warp in spacetime lets astronomers watch the same star explode four times

March 8, 2015 / / 0 Comments



Excerpt from csmonitor.com

Thanks to a phenomenon known as gravitational lensing, the Hubble Space Telescope has captured four images of the same supernova explosion.

For the first time, a cosmic magnifying glass has allowed scientists to see the same star explosion four times, possibly offering a revealing glimpse into these explosive stellar deaths and the nature of the accelerating universe.

Astronomers using the Hubble Space Telescope have captured four images of a supernova explosion in deep space thanks to a galaxy located between Earth and the massive star explosion. You can see how Hubble saw the supernova in this NASA video. The galaxy cluster warped the fabric of space and time around it — like a bowling ball placed on a bed sheet — allowing scientists to see the supernova in four images.

"It was predicted 50 years ago that a supernova could be gravitationally lensed like this, but it's taken a long time for someone to find an example," lead study author Patrick Kelly, an astronomer at the University of California, Berkeley told Space.com. "It's fun to have been able to find the first one." 

The supernova, which was discovered on Nov. 11, 2014, is located about 9.3 billion light-years away from Earth, near the edge of the observable universe. The researchers have named the distant supernova SN Refsdal in honor of the late Norwegian astrophysicist Sjur Refsdal, a pioneer of gravitational lensing studies. Due to gravitational lensing, "the supernova appears 20 times brighter than its normal brightness," study co-author Jens Hjorth, head of the Dark Cosmology Centre at the Niels Bohr Institute at the University of Copenhagen, said in a statement.
The lensing galaxy, which is about 5 billion light-years from Earth, is part of a large cluster of galaxies known MACS J1149.6+2223. In 2009, astronomers discovered that this cluster was the source of the largest known image of a spiral galaxy ever seen through a gravitational lens.

The four images of the supernova each appeared separately over the course of a few weeks. This is because light can take various paths around and through a gravitational lens, arriving at Earth at different times.

Using gravity as a lens

Gravity is created when matter warps the fabric of reality. The greater the mass of an object, the more space-time curves around that object and the stronger its gravitational pull, the discovery enshrined in Einstein's theory of general relativity, which celebrates its centennial this year.

As a result, gravity can also bend light like a lens, meaning objects see n behind powerful gravitational fields, such as those of massive galaxies, are magnified. Gravitational lensing was first discovered in 1979, and today gravitational lenses can help astronomers see features otherwise too distant and faint to detect with even the largest telescopes.

"These gravitational lenses are like a natural magnifying glass. It's like having a much bigger telescope," Kelly said in a statement. "We can get magnifications of up to 100 times by looking through these galaxy clusters."

When light is far from a gravitationally lensing mass, or if the gravitationally lensing mass is not especially large, only "weak lensing" occurs, barely distorting the light. However, when the light comes from almost exactly behind the gravitationally lensing mass, "strong lensing" can happen. 

When a strongly lensed object occupies a large patch of space — for instance, if it's a galaxy — it can get smeared into an "Einstein ring" surrounding a gravitationally lensing mass. However, strong lensing of small, pointlike items — for instance, super-bright objects known as quasars — often produces multiple images surrounding the gravitationally lensing mass, resulting in a so-called "Einstein cross."

The observations of SN Refsdal mark the first time astronomers on Earth have witnessed strong lensing of a  supernova, with four images of an exploding star arrayed as an Einstein cross.

An expanding universe

These new findings could help scientists measure the accelerating rate at which the universe is expanding, researchers say.

A computer model of the lensing cluster suggests the scientists missed chances to see the lensed supernova 50 and 10 years ago. However, the model also suggests more images of the explosion will repeat again within the next 10 years.

The timing of when all these images of the supernova arrive depends on the gravitational pull of the matter generating the gravitational lens. So, by measuring those times, the researchers hope to map how visible normal matter and invisible dark matter is distributed in the lensing galaxy.

Dark matter is currently one of the greatest mysteries in science, a poorly understood substance thought to make up five-sixths of all matter in the universe. A better understanding of how dark matter is behaving in this gravitationally lensing cluster might help shed light on the material's nature, Kelly said.

Analyzing when the images arrive could also help scientists pinpoint the rate at which the universe is expanding. Although there are already several ways to measure the cosmic expansion rate, "there has been a lot of heated debate between different methods, so it'd be interesting to see how this new technique might affect the area," Kelly said. "It's always nice to have completely independent measurements of the same quantity."

The scientists detailed their findings in the March 6 issue of the journal Science.

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Hubble’s ‘Einstein Cross’ Marks the Space-Warping Spot

March 6, 2015 / / 0 Comments


Image: Einstein Cross revealed
Flash from the supernova's blast has been warped into four points of light surrounding an elliptical galaxy in a cluster called MACS J1149.2+2223, which is 5 billion light-years away in the constellation Leo.


Excerpt from nbcnews.com
By Alan Boyle


One hundred years after Albert Einstein published his theory of general relativity, the Hubble Space Telescope has provided a demonstration of the theory at work: a picture of a distant galaxy so massive that its gravitational field is bending the light from an even more distant supernova. 

The image, released Thursday, shows how the flash from the supernova's blast has been warped into four points of light surrounding an elliptical galaxy in a cluster called MACS J1149.2+2223, which is 5 billion light-years away in the constellation Leo. 

"It really threw me for a loop when I spotted the four images surrounding the galaxy," Patrick Kelly, an astronomer from the University of California at Berkeley, said in a news release. "It was a complete surprise." 

Maybe it shouldn't have been. The configuration is known as an Einstein Cross. It's a well-known but rarely seen effect of gravitational lensing, which is in line with Einstein's assertion that a massive object warps the fabric of space-time — and thus warps the path taken by light rays around the object. 

In this case, the light rays are coming from a stellar explosion that's directly behind the galaxy, but 4.3 million light-years more distant. Computer models suggest that the four-pointed cross will eventually fade away, to be followed within the next five years by the reappearance of the supernova's flash as a single image. 

Kelly is part of a research collaboration known as the Grism Lens Amplified Survey from Space, or GLASS. The collaboration is working with the Frontier Field Supernova team, or FrontierSN, to analyze the exploding star. He's also the lead author of a paper on the phenomenon that's being published this week by the journal Science as part of a package marking the 100th anniversary of Einstein's general relativity theory. 

The researchers suggest that a high-resolution analysis of the gravitational lensing effect can lead to better measurements of cosmic distances and galactic masses, including the contribution from dark matter. The Hubble team says the faraway supernova has been named "Refsdal" in honor of Norwegian astronomer Sjur Refsdal, who proposed using time-delayed images from a lensed supernova to study the expansion of the universe. 

"Astronomers have been looking to find one ever since," UCLA astronomer Tommaso Treu, the GLASS project's principal investigator, said in Thursday's news release. "The long wait is over!" 

The Einstein Cross is the subject of a Google+ Hangout at 3 p.m. ET Thursday, presented by the Hubble science team. You can watch the event now or later via YouTube. Check out a preprint version of the Science report.

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Astronomers find star speeding out of the galaxy

March 5, 2015 / / 0 Comments





(Reuters) - Astronomers have found a star hurtling through the galaxy faster than any other, the result of being blasted away by the explosion of a massive partner star, researchers said on Thursday.
The star, known as US 708, is traveling at about 746 miles (1,200 km) per second, fast enough to actually leave the Milky Way galaxy in about 25 million years, said astronomer Stephan Geier with Germany-based European Southern Observatory, which operates three telescopes in Chile.

"At that speed you could travel from Earth to the moon in five minutes," noted University of Hawaii astronomer Eugene Magnier.
US 708 is not the first star astronomers have found that is moving fast enough to escape the galaxy, but it is the only one so far that appears to have been slingshot in a supernova explosion.

The 20 other stars discovered so far that are heading out of the galaxy likely got their impetus from coming too close to the supermassive black hole that lives at the center of the Milky Way, scientists report in an article in this week’s edition of the journal Science.

Before it was sent streaming across the galaxy, US 708 was once a cool giant star, but it was stripped of nearly all of its hydrogen by a closely orbiting partner. Scientists suspect it was this feeding that triggered the partner’s detonation.

If confirmed, these types of ejected stars may provide more insight into how supernova explosions occur. Since the explosions give off a fairly standard amount of radiation, scientists can calculate their distances by measuring how bright or dim they appear and determine how fast the universe is expanding.

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Do we really want to know if we’re not alone in the universe?

March 4, 2015 / / 0 Comments



Frank Drake, the founder of Search for Extraterrestrial Intelligence (SETI), at his home in Aptos, Calif. (Ramin Rahimian for The Washington Post)


Excerpt from washingtonpost.com

It was near Green Bank, W.Va., in 1960 that a young radio astronomer named Frank Drake conducted the first extensive search for alien civilizations in deep space. He aimed the 85-foot dish of a radio telescope at two nearby, sun-like stars, tuning to a frequency he thought an alien civilization might use for interstellar communication.

But the stars had nothing to say.

So began SETI, the Search for Extraterrestrial Intelligence, a form of astronomical inquiry that has captured the imaginations of people around the planet but has so far failed to detect a single “hello.” Pick your explanation: They’re not there; they’re too far away; they’re insular and aloof; they’re zoned out on computer games; they’re watching us in mild bemusement and wondering when we’ll grow up.

Now some SETI researchers are pushing a more aggressive agenda: Instead of just listening, we would transmit messages, targeting newly discovered planets orbiting distant stars. Through “active SETI,” we’d boldly announce our presence and try to get the conversation started.

Naturally, this is controversial, because of . . . well, the Klingons. The bad aliens.

 NASA discovers first Earth-size planet in habitable zone of another star

"NASA's Kepler Space Telescope has discovered the first validated Earth-size planet orbiting in the habitable zone of a distant star, an area where liquid water might exist on its surface. The planet, Kepler-186f, is ten percent larger in size than Earth and orbits its parent star, Kepler-186, every 130 days. The star, located about 500 light-years from Earth, is classified as an M1 dwarf and is half the size and mass of our sun." (NASA Ames Research Center)
“ETI’s reaction to a message from Earth cannot presently be known,” states a petition signed by 28 scientists, researchers and thought leaders, among them SpaceX founder Elon Musk. “We know nothing of ETI’s intentions and capabilities, and it is impossible to predict whether ETI will be benign or hostile.”

This objection is moot, however, according to the proponents of active SETI. They argue that even if there are unfriendlies out there, they already know about us. That’s because “I Love Lucy” and other TV and radio broadcasts are radiating from Earth at the speed of light. Aliens with advanced instruments could also detect our navigational radar beacons and would see that we’ve illuminated our cities.

“We have already sent signals into space that will alert the aliens to our presence with the transmissions and street lighting of the last 70 years,” Seth Shostak, an astronomer at the SETI Institute in California and a supporter of the more aggressive approach, has written. “These emissions cannot be recalled.”

That’s true only to a point, say the critics of active SETI. They argue that unintentional planetary leakage, such as “I Love Lucy,” is omnidirectional and faint, and much harder to detect than an intentional, narrowly focused signal transmitted at a known planet.

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Should Humanity Try to Contact Alien Civilizations?

March 1, 2015 / / 0 Comments



Some researchers want to use big radio dishes like the 305-meter Arecibo Observatory in Puerto Rico to announce our presence to intelligent aliens.

Excerpt from space.com
by Mike Wall

 Is it time to take the search for intelligent aliens to the next level?
For more than half a century, scientists have been scanning the heavens for signals generated by intelligent alien life. They haven't found anything conclusive yet, so some researchers are advocating adding an element called "active SETI" (search for extraterrestrial intelligence) — not just listening, but also beaming out transmissions of our own designed to catch aliens' eyes.

Active SETI "may just be the approach that lets us make contact with life beyond Earth," Douglas Vakoch, director of interstellar message composition at the SETI Institute in Mountain View, California, said earlier this month during a panel discussion at the annual meeting of the American Association for the Advancement of Science (AAAS) in San Jose.

Seeking contact


Vakoch envisions using big radio dishes such as the Arecibo Observatory in Puerto Rico to blast powerful, information-laden transmissions at nearby stars, in a series of relatively cheap, small-scale projects.

"Whenever any of the planetary radar folks are doing their asteroid studies, and they have an extra half an hour before or after, there's always a target star readily available that they can shift to without a lot of extra slough time," he said.

The content of any potential active SETI message is a subject of considerable debate. If it were up to astronomer Seth Shostak, Vakoch's SETI Institute colleague, we'd beam the entire Internet out into space.

"It's like sending a lot of hieroglyphics to the 19th century — they [aliens] can figure it out based on the redundancy," Shostak said during the AAAS discussion. "So, I think in terms of messages, we should send everything."

While active SETI could help make humanity's presence known to extrasolar civilizations, the strategy could also aid the more traditional "passive" search for alien intelligence, Shostak added.
"If you're going to run SETI experiments, where you're trying to listen for a putative alien broadcast, it may be very instructive to have to construct a transmitting project," he said. "Because now, you walk a mile in the Klingons' shoes, assuming they have them."

Cause for concern?

But active SETI is a controversial topic. Humanity has been a truly technological civilization for only a few generations; we're less than 60 years removed from launching our first satellite to Earth orbit, for example. So the chances are that any extraterrestrials who pick up our signals would be far more advanced than we are. 

This likelihood makes some researchers nervous, including famed theoretical physicist Stephen Hawking.

"Such advanced aliens would perhaps become nomads, looking to conquer and colonize whatever planets they could reach," Hawking said in 2010 on an episode of "Into the Universe with Stephen Hawking," a TV show that aired on the Discovery Channel. "If so, it makes sense for them to exploit each new planet for material to build more spaceships so they could move on. Who knows what the limits would be?"

Astrophysicist and science fiction author David Brin voiced similar concerns during the AAAS event, saying there's no reason to assume that intelligent aliens would be altruistic.

"This is an area in which discussion is called for," Brin said. "What are the motivations of species that they might carry with them into their advanced forms, that might color their cultures?"

Brin stressed that active SETI shouldn't be done in a piecemeal, ad hoc fashion by small groups of astronomers.

"This is something that should be discussed worldwide, and it should involve our peers in many other specialties, such as history," he said. "The historians would tell us, 'Well, gee, we have some examples of first-contact scenarios between advanced technological civilizations and not-so-advanced technological civilizations.' Gee, how did all of those turn out? Even when they were handled with goodwill, there was still pain."

Out there already

Vakoch and Shostak agreed that international discussion and cooperation are desirable. But Shostak said that achieving any kind of consensus on the topic of active SETI may be difficult. For example, what if polling reveals that 60 percent of people on Earth are in favor of the strategy, while 40 percent are opposed?

"Do we then have license to go ahead and transmit?" Shostak said. "That's the problem, I think, with this whole 'let's have some international discussion' [idea], because I don't know what the decision metric is."

Vakoch and Shostak also said that active SETI isn't as big a leap as it may seem at first glance: Our civilization has been beaming signals out into the universe unintentionally for a century, since the radio was invented.

"The reality is that any civilization that has the ability to travel between the stars can already pick up our accidental radio and TV leakage," Vakoch said. "A civilization just 200 to 300 years more advanced than we are could pick up our leakage radiation at a distance of several hundred light-years. So there are no increased dangers of an alien invasion through active SETI."

But Brin disputed this assertion, saying the so-called "barn door excuse" is a myth.

"It is very difficult for advanced civilizations to have picked us up at our noisiest in the 1980s, when we had all these military radars and these big television antennas," he said.

Shostak countered that a fear of alien invasion, if taken too far, could hamper humanity's expansion throughout the solar system, an effort that will probably require the use of high-powered transmissions between farflung outposts.

"Do you want to hamstring all that activity — not for the weekend, not just shut down the radars next week, or active SETI this year, but shut down humanity forever?" Shostak said. "That's a price I'm not willing to pay."

So the discussion and debate continues — and may continue for quite some time.

"This is the only really important scientific field without any subject matter," Brin said. "It's an area in which opinion rules, and everybody has a very fierce opinion."

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As Dawn Spacecraft Approaches, A Second Mysterious Light Emerges on Planet Ceres

February 27, 2015 / / 0 Comments

Photo : NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI Excerpt from sciencetimes.com Originally discovered in 1801 by an astronomer in Sicily, Ceres has had quite an interesting history to date. Originally believed to be a shining star in the sky, when i...

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UK Scientists: Aliens May Have Sent Space Seeds To Create Life On Earth

February 21, 2015 / / 0 Comments

Excerpt from huffingtonpost.comScientists in the U.K. have examined a tiny metal circular object, and are suggesting it might be a micro-organism deliberately sent by extraterrestrials to create life on Earth.Don't be fooled by the size of the objec...

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Cluster Filled with Dark Matter May House ‘Failed Galaxies’

February 21, 2015 / / 0 Comments

The Coma Cluster


Excerpt space.com

 A strange set of 48 galaxies appears to be rich in dark matter and lacking in stars, suggesting that they may be so-called "failed" galaxies, a new study reports.

The galaxies in question are part of the Coma Cluster, which lies 300 million light-years from Earth and packs several thousand galaxies into a space just 20 million light-years across. To study them, Pieter van Dokkum of Yale University and his colleagues used the Dragonfly Telephoto Array in New Mexico.

The array's eight connected Canon telephoto lenses allow the researchers to search for extremely faint objects that traditional telescope surveys miss. Often, such as when the researchers used the array to search for the faint glow that dark matter might create, the hunt comes up empty. 


But when van Dokkum and his colleagues looked toward the Coma Cluster, they found a pleasant surprise.

"We noticed all these faint little smudges in the images from the Dragonfly telescope," van Dokkum told Space.com.

The mysterious blobs nagged at van Dokkum, compelling him to look into the objects further. Fortuitously, NASA's Hubble Space Telescope had recently captured one of these objects with its sharp eye. 

"It turned out that they're these fuzzy blobs that look somewhat like dwarf spheroidal galaxies around our own Milky Way," van Dokkum said. "So they looked familiar in some sense … except that if they are at the distance of the Coma Cluster, they must be really huge."

And with very few stars to account for the mass in these galaxies, they must contain huge amounts of dark matter, the researchers said. In fact, to stay intact, the 48 galaxies must contain 98 percent dark matter and just 2 percent "normal" matter that we can see. The fraction of dark matter in the universe as a whole is thought to be around 83 percent. 

But before making this claim, the team had to verify that these blobs really are as distant as the Coma Cluster. (In fact, the team initially thought the galaxies were much closer.). But even in the Hubble image the stars were not resolved. If Hubble — one of the most powerful telescopes in existence — can't resolve the stars, those pinpricks of light must be pretty far away, study team members reasoned. 

Now, van Dokkum and his colleagues have definitive evidence: They've determined the exact distance to one of the galaxies. The team used the Keck Telescope in Hawaii to look at one of the objects for two hours. This gave them a hazy spectrum, from which they were able to tease out the galaxy's recessional velocity — that is, how fast it is moving away from Earth.

That measure traces back to the Hubble Telescope's namesake. In 1929, American astronomer Edwin Hubble discovered one of the simplest and most surprising relationships in astronomy: The more distant a galaxy, the faster it moves away from the Milky Way.

Today, astronomers use the relationship to measure a galaxy's recessional velocity and thus calculate the galaxy's distance. In this case, the small fuzzy blob observed with Keck was moving away from Earth at 15.7 million mph (25.3 million km/h). That places it at 300 million light-years away from Earth, the distance of the Coma Cluster.

So the verdict is officially in: These galaxies must be associated with the Coma Cluster and therefore must be extremely massive.
"It looks like the universe is able to make unexpected galaxies," van Dokkum said, adding that there is an amazing diversity of massive galaxies.

But the clusters still present a mystery: The team doesn't know why they have so much dark matter and so few stars.

Though they look serene and silent from our vantage on Earth, stars are actually roiling balls of violent plasma. Test your stellar smarts with this quiz.
One possibility is that these are "failed" galaxies. A galaxy's first supernova explosions will drive away huge amounts of gas. 

Normally, the galaxy has such a strong gravitational pull that most of the expelled gas falls back onto the galaxy and forms the next generations of stars. But maybe the strong gravitational pull of the other galaxies in the Coma Cluster interfered with this process, pulling the gas away.

"If that happened, they had no more fuel for star formation and they were sort of stillborn galaxies where they started to get going but then failed to really build up a lot of stars," said van Dokkum, adding that this is the most likely scenario. 

Another possibility is that these galaxies are in the process of being ripped apart. But astronomers expect that if this were the case, the galaxies would be distorted and streams of stars would be flowing away from them. Because these effects don't appear, this scenario is very unlikely.

The next step is to try to measure the individual motions of stars within the galaxies. If the team knew those stars' speeds, it could calculate the galaxies' exact mass, and therefore the amount of dark matter they contain. If the stars move faster, the galaxy is more massive. And if they move slower, the galaxy is less massive. 
However, this would require a better spectrum than the one the team has right now.

"But it's not outside the realm of what's possible," van Dokkum assured. "It's just very hard."

The original study has been published in Astrophysical Journal Letters. You can read it for free on the preprint site arXiv.org.

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