Showing posts with label galaxy. Show all posts
Showing posts with label galaxy. Show all posts
Sunday, May 24, 2020
Saturday, April 4, 2015
Artistic Easter Eggs
Craft blogger Allison Murray at Dream A Little Bigger has posted some artistic, beautiful alternatives to traditional dyed Easter eggs. Hurry, Easter is tomorrow!
The Galaxy Easter Egg is pretty amazing, and easy to do with a base of black paint and a spattering of space-y nebula colors on top (gold makes gas clouds, white makes stars).
Gold Leaf Easter Eggs are fairly easy as well. You can buy leaf and sizing (glue) at any craft store.
And finally, a bit of watercolor or watered-down food coloring creates amorphous blobs which you can then outline, in a very loose artistic style, with a black fine-line marker to create the impression of petals and leaves on these Watercolor Easter Eggs.
For tutorials on each egg, click on either the name of the egg or a photo.
http://www.dreamalittlebigger.com/
The Galaxy Easter Egg is pretty amazing, and easy to do with a base of black paint and a spattering of space-y nebula colors on top (gold makes gas clouds, white makes stars).
Gold Leaf Easter Eggs are fairly easy as well. You can buy leaf and sizing (glue) at any craft store.
And finally, a bit of watercolor or watered-down food coloring creates amorphous blobs which you can then outline, in a very loose artistic style, with a black fine-line marker to create the impression of petals and leaves on these Watercolor Easter Eggs.
For tutorials on each egg, click on either the name of the egg or a photo.
http://www.dreamalittlebigger.com/
Friday, March 27, 2015
Dark Matter: Now Even Stranger Than Before!
Fascinating, important science news from BBC:
Dark matter 'ghosts' through galactic smash-ups
By Jonathan Webb
Science reporter, BBC News
By observing multiple collisions between huge clusters of galaxies, scientists have witnessed dark matter coasting straight through the turmoil.
Dark matter is the mysterious, invisible stuff that makes up 85% of the matter in the cosmos - and these results rule out several theoretical models put forward to explain it.
This is because it barely interacts with anything at all, including the dark matter in the oncoming galaxies.
The work appears in Science magazine.
To conduct their study, astrophysicists looked at 72 smash-ups between galactic clusters, using two space telescopes: visible light was recorded by the Hubble Space Telescope, and X-rays by the Chandra Observatory.
Scouring multiple views of the collisions, the researchers tracked the movement of the three main components of galaxies: stars, clouds of gas, and dark matter.
The violently swirling clouds of gas are hot enough to glow with X-rays, which Chandra detects. And stars can be seen in regular, visible-light images from Hubble.
Dark matter is more difficult to "see" - but not impossible. Although it does not emit or absorb light, it does have gravity, and so it bends the path of light passing nearby. This warps our view of anything on the other side of it, in an effect called "gravitational lensing".
"Looking through dark matter is like looking through a bathroom window," said Dr Richard Massey from Durham University, one of the study's authors. "All the objects that you can see in the distance appear slightly distorted and warped."
Using this distortion allowed Dr Massey, with colleagues from the University of Edinburgh, University College London and Switzerland's Ecole Polytechnique Federale de Lausanne (EPFL), to "map" the dark matter in the clusters as they collided.
Galaxy clusters are vast and contain huge amounts of dark matter, so when they collide - over billions of years - it offers a unique glimpse of how the stuff behaves.
"We like these collisions because it's exactly what we'd do in the lab," Dr Massey told BBC News.
"If you want to figure out what something is made out of, you knock it, or you throw it across the room and see where the bits go."
In this case, the bits went straight through each other.
Unlike the gas clouds, which grind to a turbulent halt, and the stars, which mostly glide past each other, the ubiquitous dark matter passes through everything and emerges unscathed, like a ghost.
"It seems not to interact with anything at all," Dr Massey said.
Earlier observations of the "Bullet Cluster" - a bust-up between two particularly big groups of galaxies, now in its final stages - had already demonstrated dark matter's weird lack of interactions, including with itself.
But this new, major survey was able to deliver much more precision, concluding that there was even less interaction than the previous work allowed for.
"If you bang your head against the wall, the electrostatic force between the molecules in your head and the ones in the wall cause a collision. This is what dark matter doesn't seem to feel," Dr Massey explained.
Dark matter does "feel" gravity; those interactions are the reason we know it is there, and the reason it is bound up in the galactic collisions to begin with. But the lack of almost any other interaction makes it even more mysterious than before.
Link to the original BBC article:
http://www.bbc.com/news/science-environment-32066013
The original article in Science Magazine:
http://www.sciencemag.org/content/347/6229/1462
Dark matter 'ghosts' through galactic smash-ups
By Jonathan Webb
Science reporter, BBC News
By observing multiple collisions between huge clusters of galaxies, scientists have witnessed dark matter coasting straight through the turmoil.
Dark matter is the mysterious, invisible stuff that makes up 85% of the matter in the cosmos - and these results rule out several theoretical models put forward to explain it.
This is because it barely interacts with anything at all, including the dark matter in the oncoming galaxies.
The work appears in Science magazine.
To conduct their study, astrophysicists looked at 72 smash-ups between galactic clusters, using two space telescopes: visible light was recorded by the Hubble Space Telescope, and X-rays by the Chandra Observatory.
Scouring multiple views of the collisions, the researchers tracked the movement of the three main components of galaxies: stars, clouds of gas, and dark matter.
The violently swirling clouds of gas are hot enough to glow with X-rays, which Chandra detects. And stars can be seen in regular, visible-light images from Hubble.
Dark matter is more difficult to "see" - but not impossible. Although it does not emit or absorb light, it does have gravity, and so it bends the path of light passing nearby. This warps our view of anything on the other side of it, in an effect called "gravitational lensing".
"Looking through dark matter is like looking through a bathroom window," said Dr Richard Massey from Durham University, one of the study's authors. "All the objects that you can see in the distance appear slightly distorted and warped."
Using this distortion allowed Dr Massey, with colleagues from the University of Edinburgh, University College London and Switzerland's Ecole Polytechnique Federale de Lausanne (EPFL), to "map" the dark matter in the clusters as they collided.
Galaxy clusters are vast and contain huge amounts of dark matter, so when they collide - over billions of years - it offers a unique glimpse of how the stuff behaves.
"We like these collisions because it's exactly what we'd do in the lab," Dr Massey told BBC News.
"If you want to figure out what something is made out of, you knock it, or you throw it across the room and see where the bits go."
In this case, the bits went straight through each other.
Unlike the gas clouds, which grind to a turbulent halt, and the stars, which mostly glide past each other, the ubiquitous dark matter passes through everything and emerges unscathed, like a ghost.
"It seems not to interact with anything at all," Dr Massey said.
Earlier observations of the "Bullet Cluster" - a bust-up between two particularly big groups of galaxies, now in its final stages - had already demonstrated dark matter's weird lack of interactions, including with itself.
But this new, major survey was able to deliver much more precision, concluding that there was even less interaction than the previous work allowed for.
"If you bang your head against the wall, the electrostatic force between the molecules in your head and the ones in the wall cause a collision. This is what dark matter doesn't seem to feel," Dr Massey explained.
Dark matter does "feel" gravity; those interactions are the reason we know it is there, and the reason it is bound up in the galactic collisions to begin with. But the lack of almost any other interaction makes it even more mysterious than before.
Link to the original BBC article:
http://www.bbc.com/news/science-environment-32066013
The original article in Science Magazine:
http://www.sciencemag.org/content/347/6229/1462
Sunday, September 7, 2014
Laniakea
This is amazing scientific news. In a recent study for Nature, scientists R. Brent Tully, Hélène Courtois, Yehuda Hoffman, and Daniel Pomarède at the University of Hawaii mapped thousands of galaxies in the immediate vicinity of our own Milky Way, and discovered that we are part of a truly massive "supercluster" of galaxies that they named Laniakea (which means "immeasurable heavens" in Hawaiian).
They also mapped galaxies expanding outward and galaxies which are being pulled toward each other. After mapping their trajectories, they discovered these galaxies, including our own, are being pulled toward a mysterious, super-dense area called "The Great Attractor."
And in another mind-boggling leap, our supercluster structure Laniakea borders another supercluster structure called Perseus-Pisces! I think it is astounding how the structures almost mirror each other, as though a supercluster of galaxies naturally take a certain shape...
http://www.nature.com/nature/journal/v513/n7516/full/nature13674.html#videos
They also mapped galaxies expanding outward and galaxies which are being pulled toward each other. After mapping their trajectories, they discovered these galaxies, including our own, are being pulled toward a mysterious, super-dense area called "The Great Attractor."
And in another mind-boggling leap, our supercluster structure Laniakea borders another supercluster structure called Perseus-Pisces! I think it is astounding how the structures almost mirror each other, as though a supercluster of galaxies naturally take a certain shape...
http://www.nature.com/nature/journal/v513/n7516/full/nature13674.html#videos
Friday, March 15, 2013
BEAUTY: Sculpture--Mihoko Ogaki
Japanese conceptual artist Mihoko Ogaki's series "Milky Ways--Breath" features fibre-reinforced plastic figures of dying or dead people with entire galaxies or even universes inside them. Small holes in the surface of the figure allow star maps to be projected onto the surrounding walls. This simple yet profound image is breathtaking in its scope of meaning. The pieces are rife with the ideas of cycles, transformation, transmogrification, macro and micro, and our connection and place in the reality around us.
http://www.mihoko-ogaki.com/index.html
http://www.mihoko-ogaki.com/index.html
I am sure I have posted these images before, but here they are again because they are so relevant to the art of Ogaki.
Sunday, July 15, 2012
...And now, for a lot of perspective...
“Long ago, when an early galaxy began to pour light out into the surrounding darkness, no witness could have known that billions of years later some remote clumps of rock and metal, ice and organic molecules would fall together to make a place called Earth; or that life would arise and thinking beings evolve who would one day capture a little of that galactic light, and try to puzzle out what had sent it on its way. And after the earth dies, some 5 billion years from now, after it's burned to a crisp, or even swallowed by the Sun, there will be other worlds and stars and galaxies coming into being -- and they will know nothing of a place once called Earth.”
― Carl Sagan
― Carl Sagan
 |
| Conjectured illustration of the scorched Earth after the Sun has entered the red giant phase, seven billion years from now |
Friday, July 6, 2012
Proof Of Dark Matter!
This has been an amazing week for science! A new particle was announced, and now we have proof of dark matter!
Reported by Rachel Bayliss at COSMOS on-line:
LONDON: The fundamental ‘cosmic web’ of dark matter throughout the universe has finally been observed from Earth, confirming theories of how the universe was shaped.
“This result is a resounding confirmation of a key prediction of structure formation in the universe,” said Jörg Dietrich from University Observatory Munich, Germany, and lead author of the study published in Nature today.
“Not only did we for the first time see a dark matter filament directly, we also confirmed that it’s total mass [dark matter plus normal matter] and the amount of hot gas are in agreement with predictions.”
DARK MATTER
Large cosmic structures, such as galaxies, exhibit gravitational affects that cannot be justified by the amount of normal matter present in the universe. A principle exists to describe this behavior and is known as the cold-dark-matter model, and it is the foundation of modern cosmology.
Within the model, vast quantities of dark matter, moving much slower than the speed of light (cold), must exist to explain the gravitational affects seen on normal matter.
As the name implies, dark matter cannot be observed in the traditional sense as it does not emit or absorb light at any significant level. However, its presence can be detected.
GRAVITATIONAL LENSING
“The technique we used is gravitational lensing,” said Dietrich. This is where light from, for example, a distant galaxy, is deflected and bent by huge gravitational fields generated by other similarly large objects. “It was widely believed that with current telescopes we would not be able to image dark matter filament with gravitational lensing.”
Dietrich and his team devised a method to boost the lensing signal sufficiently so that the dark matter filament between two clusters of galaxies could be observed with an 8m ground-based telescope.
“The key ingredient that made this result possible, is that we decided to study a very peculiar system of two massive galaxy clusters,” he said. These are called Abell 222 and Abell 223.
“Gravitational lensing is now allowing us to see parts of the universe that were previously invisible,” said astrophysicist Joanna Dunkley, from the University of Oxford, England, who was not involved in the study. “We already have plenty of indirect evidence that galaxy clusters trace a cosmic web of dark matter, but seeing this directly is an important step forward.”
THE COSMIC WEB
She added: “Our standard picture of cosmology tells us that filaments of invisible matter thread through the universe, and this bridge of dark matter connecting two clusters is exactly what we would expect.”
The research confirms that galaxy clusters form at the intersections of these vast filaments of dark matter.
Keen to develop this ground-breaking research further, Dietrich said, “We now want to study the interplay of dark matter density and galaxy population to get a better understanding of the mechanism that transforms galaxies from blue, star-forming spiral galaxies – which are the most common galaxies in filament – to red elliptical galaxies, which are the majority of galaxies in galaxy clusters.”
“The dark matter web makes up about a quarter of the universe,” Dunkley explained. “Being able to measure its morphology should help tell us more about how galaxies and clusters were formed, and may even give us a clue about what the dark matter itself is.” This in itself is a question that has been fascinating scientists for decades.
This research states that the underlying dark matter structure of the universe could comprise over half of all matter in existence. So developing it further is a must if scientists are to understand the elementary nature of the universe.
“We need to observe the lensing signal of more filaments to understand how special the one we found is,” Dietrich said. This will involve both in-depth statistical analysis of thousands of galaxy clusters, and a satellite mission to increase the possibilities of directly observing dark matter filaments.
http://www.cosmosmagazine.com/news/5765/scientists-shine-light-dark-matter
Reported by Rachel Bayliss at COSMOS on-line:
LONDON: The fundamental ‘cosmic web’ of dark matter throughout the universe has finally been observed from Earth, confirming theories of how the universe was shaped.
“This result is a resounding confirmation of a key prediction of structure formation in the universe,” said Jörg Dietrich from University Observatory Munich, Germany, and lead author of the study published in Nature today.
“Not only did we for the first time see a dark matter filament directly, we also confirmed that it’s total mass [dark matter plus normal matter] and the amount of hot gas are in agreement with predictions.”
Galaxy clusters Abell 222 and Abell 223 connected by dark matter filament.
Yellow contours and blue shading are indicative of matter density.
Credit: Jörg Dietrich, University of Michigan/University Observatory Munich
DARK MATTER
Large cosmic structures, such as galaxies, exhibit gravitational affects that cannot be justified by the amount of normal matter present in the universe. A principle exists to describe this behavior and is known as the cold-dark-matter model, and it is the foundation of modern cosmology.
Within the model, vast quantities of dark matter, moving much slower than the speed of light (cold), must exist to explain the gravitational affects seen on normal matter.
As the name implies, dark matter cannot be observed in the traditional sense as it does not emit or absorb light at any significant level. However, its presence can be detected.
GRAVITATIONAL LENSING
“The technique we used is gravitational lensing,” said Dietrich. This is where light from, for example, a distant galaxy, is deflected and bent by huge gravitational fields generated by other similarly large objects. “It was widely believed that with current telescopes we would not be able to image dark matter filament with gravitational lensing.”
Dietrich and his team devised a method to boost the lensing signal sufficiently so that the dark matter filament between two clusters of galaxies could be observed with an 8m ground-based telescope.
“The key ingredient that made this result possible, is that we decided to study a very peculiar system of two massive galaxy clusters,” he said. These are called Abell 222 and Abell 223.
“Gravitational lensing is now allowing us to see parts of the universe that were previously invisible,” said astrophysicist Joanna Dunkley, from the University of Oxford, England, who was not involved in the study. “We already have plenty of indirect evidence that galaxy clusters trace a cosmic web of dark matter, but seeing this directly is an important step forward.”
THE COSMIC WEB
She added: “Our standard picture of cosmology tells us that filaments of invisible matter thread through the universe, and this bridge of dark matter connecting two clusters is exactly what we would expect.”
The research confirms that galaxy clusters form at the intersections of these vast filaments of dark matter.
Keen to develop this ground-breaking research further, Dietrich said, “We now want to study the interplay of dark matter density and galaxy population to get a better understanding of the mechanism that transforms galaxies from blue, star-forming spiral galaxies – which are the most common galaxies in filament – to red elliptical galaxies, which are the majority of galaxies in galaxy clusters.”
“The dark matter web makes up about a quarter of the universe,” Dunkley explained. “Being able to measure its morphology should help tell us more about how galaxies and clusters were formed, and may even give us a clue about what the dark matter itself is.” This in itself is a question that has been fascinating scientists for decades.
This research states that the underlying dark matter structure of the universe could comprise over half of all matter in existence. So developing it further is a must if scientists are to understand the elementary nature of the universe.
“We need to observe the lensing signal of more filaments to understand how special the one we found is,” Dietrich said. This will involve both in-depth statistical analysis of thousands of galaxy clusters, and a satellite mission to increase the possibilities of directly observing dark matter filaments.
http://www.cosmosmagazine.com/news/5765/scientists-shine-light-dark-matter
Saturday, July 2, 2011
Tens Of Millions Of Suns
Amateur astronomer and photographer Nick Risinger traveled 60,000 miles around the globe with six synchronized cameras to photograph the night sky. The resulting 5,000 megapixel picture of the entire Milky Way is stitched together from a mind boggling 37,440 individual shots.
Risinger has set up a website that features a high resolution version of his panoramic portrait of the Milky Way with an amazing zoom feature. Visit it (link below) and marvel at tens of millions of suns, "still perhaps only a hundredth of one percent thought to exist in our galaxy alone."
http://skysurvey.org/
Risinger has set up a website that features a high resolution version of his panoramic portrait of the Milky Way with an amazing zoom feature. Visit it (link below) and marvel at tens of millions of suns, "still perhaps only a hundredth of one percent thought to exist in our galaxy alone."http://skysurvey.org/
Thursday, April 21, 2011
Happy Birthday, Hubble
Today is the 21st anniversary of the Hubble Telescope in orbit. NASA's Astronomy Picture of the Day celebrates this with the below image and information.
Happy Birthday, Hubble!
Peculiar Galaxies of Arp 273
Credit: NASA, ESA, and the Hubble Heritage Team (STScI / AURA)
Explanation: The spiky stars in the foreground of this sharp cosmic portrait are well within our own Milky Way Galaxy. The two eye-catching galaxies lie far beyond the Milky Way, at a distance of over 300 million light-years. Their distorted appearance is due to gravitational tides as the pair engage in close encounters. Cataloged as Arp 273 (also as UGC 1810), the galaxies do look peculiar, but interacting galaxies are now understood to be common in the universe. In fact, the nearby large spiral Andromeda Galaxy is known to be some 2 million light-years away and approaching the Milky Way. Arp 273 may offer an analog of their far future encounter. Repeated galaxy encounters on a cosmic timescale can ultimately result in a merger into a single galaxy of stars. From our perspective, the bright cores of the Arp 273 galaxies are separated by only a little over 100,000 light-years. The release of this stunning vista celebrates the 21st anniversary of the Hubble Space Telescope in orbit.
NASA Astronomy Picture of the Day site:
http://apod.nasa.gov/apod/archivepix.html
Happy Birthday, Hubble!
Peculiar Galaxies of Arp 273
Credit: NASA, ESA, and the Hubble Heritage Team (STScI / AURA)
Explanation: The spiky stars in the foreground of this sharp cosmic portrait are well within our own Milky Way Galaxy. The two eye-catching galaxies lie far beyond the Milky Way, at a distance of over 300 million light-years. Their distorted appearance is due to gravitational tides as the pair engage in close encounters. Cataloged as Arp 273 (also as UGC 1810), the galaxies do look peculiar, but interacting galaxies are now understood to be common in the universe. In fact, the nearby large spiral Andromeda Galaxy is known to be some 2 million light-years away and approaching the Milky Way. Arp 273 may offer an analog of their far future encounter. Repeated galaxy encounters on a cosmic timescale can ultimately result in a merger into a single galaxy of stars. From our perspective, the bright cores of the Arp 273 galaxies are separated by only a little over 100,000 light-years. The release of this stunning vista celebrates the 21st anniversary of the Hubble Space Telescope in orbit.
NASA Astronomy Picture of the Day site:
http://apod.nasa.gov/apod/archivepix.html
Tuesday, March 1, 2011
Tuesday, February 1, 2011
Friday, January 28, 2011
One Step Closer To Black Holes
For Fully Mature Black Holes, Time Stands Still
By Clara Moskowitz, SPACE.com Senior Writer
space.com – Thu Jan 27, 3:30 pm ET
The end of a black hole’s evolution may be a mind-bending kind of space-time independent of time. A new study proposes a method to tell how far any black hole is from reaching this end state.
Black holes are some of the weirdest things in the universe. They occur when mass is packed into a tiny volume, squished to its ultimate density.
Though observations suggest black holes are prevalent in the universe, scientists still don't really understand what goes on inside them. The equations of general relativity usually used to understand the physics of the universe break down in these cases.
"It is really beyond the physics we know," said Juan Antonio Valiente Kroon, a mathematician at Queen Mary, University of London. "To understand what happens inside a black hole, we need to invent new physics."
Mercifully, the physics for the end state of a black hole is somewhat simpler. A solution to the equations of general relativity was found that produced a situation called "Kerr spacetime." Scientists now think Kerr spacetime is what happens when a black hole has reached its final evolutionary state.
"Mainly the equations of relativity are so complex that for relativistic systems, the only way you can probe these equations is by means of computer," Valiente Kroon told SPACE.com. "Solutions like this Kerr solution are really exceptional. The Kerr solution is one of the few explicitly known solutions to general relativity that have a direct physical meaning."
Kerr spacetime is time-independent, meaning that nothing in Kerr spacetime changes over time. In effect, time stands still. A black hole in such a state is essentially stationary.
"One could say once it has reached this stage, there are no further processes taking place," Valiente Kroon said.
In their new study, Valiente Kroon and Thomas Backdahl, his colleague at Queen Mary, have calculated a formula to determine how close a black hole is to reaching the Kerr state.
This can happen very quickly – even in seconds – depending on the object's mass.
To apply the formula, scientists would examine the region around a black hole called its event horizon. Once mass, or even light, passes within the event horizon of a black hole, it cannot escape the black hole's gravitational clutches.
The researchers think their development could aid scientists who are building computer simulations of black holes and aiming to align them with observations of actual black holes.
Astronomers think most galaxies, including our own Milky Way, host supermassive black holes in their centers. Some researchers suspect that these are actually Kerr black holes.
Valiente Kroon and Backdahl detail their work in the Jan. 19 issue of the journal Proceedings of the Royal Society A.
By Clara Moskowitz, SPACE.com Senior Writer
space.com – Thu Jan 27, 3:30 pm ET
The end of a black hole’s evolution may be a mind-bending kind of space-time independent of time. A new study proposes a method to tell how far any black hole is from reaching this end state.
Black holes are some of the weirdest things in the universe. They occur when mass is packed into a tiny volume, squished to its ultimate density.
Though observations suggest black holes are prevalent in the universe, scientists still don't really understand what goes on inside them. The equations of general relativity usually used to understand the physics of the universe break down in these cases.
"It is really beyond the physics we know," said Juan Antonio Valiente Kroon, a mathematician at Queen Mary, University of London. "To understand what happens inside a black hole, we need to invent new physics."
Mercifully, the physics for the end state of a black hole is somewhat simpler. A solution to the equations of general relativity was found that produced a situation called "Kerr spacetime." Scientists now think Kerr spacetime is what happens when a black hole has reached its final evolutionary state.
"Mainly the equations of relativity are so complex that for relativistic systems, the only way you can probe these equations is by means of computer," Valiente Kroon told SPACE.com. "Solutions like this Kerr solution are really exceptional. The Kerr solution is one of the few explicitly known solutions to general relativity that have a direct physical meaning."
Kerr spacetime is time-independent, meaning that nothing in Kerr spacetime changes over time. In effect, time stands still. A black hole in such a state is essentially stationary.
"One could say once it has reached this stage, there are no further processes taking place," Valiente Kroon said.
In their new study, Valiente Kroon and Thomas Backdahl, his colleague at Queen Mary, have calculated a formula to determine how close a black hole is to reaching the Kerr state.
This can happen very quickly – even in seconds – depending on the object's mass.
To apply the formula, scientists would examine the region around a black hole called its event horizon. Once mass, or even light, passes within the event horizon of a black hole, it cannot escape the black hole's gravitational clutches.
The researchers think their development could aid scientists who are building computer simulations of black holes and aiming to align them with observations of actual black holes.
Astronomers think most galaxies, including our own Milky Way, host supermassive black holes in their centers. Some researchers suspect that these are actually Kerr black holes.
Valiente Kroon and Backdahl detail their work in the Jan. 19 issue of the journal Proceedings of the Royal Society A.
Thursday, December 2, 2010
One Step Closer To Infinity
Starry, Starry, Starry Night: Star Count May Triple!
WASHINGTON – The universe may glitter with far more stars than even Carl Sagan imagined when he rhapsodized about billions upon billions. A new study suggests there are a mind-blowing 300 sextillion of them, or three times as many as scientists previously calculated. That is a 3 followed by 23 zeros. Or 3 trillion times 100 billion.
The estimate, contained in a study published online Wednesday in the journal Nature, is based on findings that there are many more red dwarf stars--the most common star in the universe--than once thought.
But the research goes deeper than that. The study by Yale University astronomer Pieter van Dokkum and Harvard astrophysicist Charlie Conroy questions a key assumption that astronomers often use: that most galaxies have the same properties as our Milky Way. And that conclusion is deeply unsettling to astronomers who want a more orderly cosmos.
When scientists previously estimated the total number of stars, they assumed that all galaxies had the same ratio of dwarf stars as the Milky Way, which is spiral-shaped. Much of our understanding of the universe is based on observations made inside our own galaxy and then extrapolated to other galaxies.
But about one-third of the galaxies in the universe are elliptical, not spiral, and van Dokkum found they aren't really made up the same way as ours.
Using the Keck telescope in Hawaii, van Dokkum and a colleague gazed into eight distant, elliptical galaxies and looked at their hard-to-differentiate light signatures. The scientists calculated that elliptical galaxies have more red dwarf stars than predicted. A lot more.
"We're seeing 10 or 20 times more stars than we expected," van Dokkum said.
Generally scientists believe there are 100 billion to a trillion galaxies in the universe. And each galaxy — the Milky Way included — was thought to have 100 billion to a trillion stars. Sagan, the Cornell University scientist and best-selling author who was often impersonated by comedians as saying "billions and billions," usually said there were 100 billion galaxies, each with 100 billion stars.
Van Dokkum's work takes these numbers and adjusts them. That's because some of those galaxies — the elliptical ones, which account for about a third of all galaxies — have as many as 1 trillion to 10 trillion stars, not a measly 100 billion. When van Dokkum and Conroy crunched the incredibly big numbers, they found that it tripled the estimate of stars in the universe from 100 sextillion to 300 sextillion.
That's a huge number to grasp, even for astronomers who are used to dealing in light years and trillions, Conroy said.
"It's fun because it gets you thinking about these large numbers," Conroy said. Conroy looked up how many cells are in the average human body — 50 trillion or so — and multiplied that by the 6 billion people on Earth. And he came up with about 300 sextillion.
So the number of stars in the universe "is equal to all the cells in the humans on Earth — a kind of funny coincidence," Conroy said.
For the past month, astronomers have been buzzing about van Dokkum's findings, and many aren't too happy about them, said astronomer Richard Ellis of the California Institute of Technology.
Saturday, November 13, 2010
One Step Closer To Dark Matter
Astronomers have created a new, incredibly detailed map of dark matter by using the Hubble Space Telescope to peer through a huge cluster of galaxies as if it were a cosmic magnifying glass.
Though invisible, dark matter makes its presence known through its gravitational tug on normal stuff. Scientists now calculate that dark matter could make up 80 percent of all the matter in the universe.
The new dark matter map could reveal secrets not just about dark matter, but about its equally enigmatic sibling, dark energy. This is the name given to the perplexing force that is pulling against gravity, causing the universe to balloon in size ever more rapidly.
The dark matter map was created with observations from the Hubble telescope of a large galaxy cluster called Abell 1689, located 2.2 billion light-years from Earth. This cluster is famous as a stunning example of gravitational lensing – a phenomenon predicted by Einstein that happens when massive objects warp the space-time around them, causing even light to travel on a bent path when it passes by.
When astronomers look at Abell 1689, they can see distorted pictures of the galaxies that lie beyond it in our line of sight: As those galaxies' light travels from them to us, it passes through Abell 1689 and is bent and magnified.
By studying this so-called lensing effect, scientists can deduce the mass that is causing the warping.
Astronomer Dan Coe of NASA's Jet Propulsion Laboratory in Pasadena, Calif., and Edward Fuselier of the United States Military Academy at West Point teamed up to apply a new mathematical formulation to Hubble observations of Abell 1689. The result is the most accurate, detailed calculation so far of the cluster's mass distribution, including the mass that can't be accounted for by the visible matter – meaning, the dark matter.
"The lensed images are like a big puzzle," Coe said. "Here we have figured out, for the first time, a way to arrange the mass of Abell 1689 such that it lenses all of these background galaxies to their observed positions."
Above: the new map of dark matter
12 November 2010
01:29 pm ET
Though invisible, dark matter makes its presence known through its gravitational tug on normal stuff. Scientists now calculate that dark matter could make up 80 percent of all the matter in the universe.
The new dark matter map could reveal secrets not just about dark matter, but about its equally enigmatic sibling, dark energy. This is the name given to the perplexing force that is pulling against gravity, causing the universe to balloon in size ever more rapidly.
The dark matter map was created with observations from the Hubble telescope of a large galaxy cluster called Abell 1689, located 2.2 billion light-years from Earth. This cluster is famous as a stunning example of gravitational lensing – a phenomenon predicted by Einstein that happens when massive objects warp the space-time around them, causing even light to travel on a bent path when it passes by.
When astronomers look at Abell 1689, they can see distorted pictures of the galaxies that lie beyond it in our line of sight: As those galaxies' light travels from them to us, it passes through Abell 1689 and is bent and magnified.
By studying this so-called lensing effect, scientists can deduce the mass that is causing the warping.
Astronomer Dan Coe of NASA's Jet Propulsion Laboratory in Pasadena, Calif., and Edward Fuselier of the United States Military Academy at West Point teamed up to apply a new mathematical formulation to Hubble observations of Abell 1689. The result is the most accurate, detailed calculation so far of the cluster's mass distribution, including the mass that can't be accounted for by the visible matter – meaning, the dark matter.
"The lensed images are like a big puzzle," Coe said. "Here we have figured out, for the first time, a way to arrange the mass of Abell 1689 such that it lenses all of these background galaxies to their observed positions."
Above: the new map of dark matter12 November 2010
01:29 pm ET
Subscribe to:
Posts (Atom)
