Showing posts with label star. Show all posts
Showing posts with label star. Show all posts

Monday, January 30, 2017

Researchers have found another planet (Wolf 1061c) that can sustain life: Located just 14 light-years away

Credit: The Wolf 1061 system. Credit: UNSW Sydney
An exoplanet with the prime conditions for life could be located just 14 light-years away, scientists report, in one of the closest neighbouring solar systems to our own.

New research suggests that a planet circling the star Wolf 1061 falls within what's called the star's habitable zone - making it one of the most likely neighbouring candidates for a planet that supports life.


This artist's concept illustrates a young, red dwarf star surrounded by three planets. Credit: wikipedia

"The Wolf 1061 system is important, because it is so close, and that gives other opportunities to do follow-up studies to see if it does indeed have life," says lead researcher Stephen Kane from San Francisco State University.

There are three planets orbiting Wolf 1061, but the planet Wolf 1061c is of particular interest.

Discovered in 2015, and with an estimated mass that's more than four times Earth's mass, Wolf 1061c is located right in the middle of Wolf 1061's habitable zone: the region where a planet's distance from its host star makes conditions suitable for liquid water and other life-supporting elements.

Our own Solar System runs by the same rules: conditions on Earth are just right for liquid water, whereas Mars is too cold.

To investigate whether Wolf 1061c might offer the same kind of habitability, the researchers analysed seven years of luminosity data from its host star and ran calculations of the exoplanet's orbit to figure out what the temperature and pressure on the surface could be.


The findings add weight to previous speculation that Wolf 1061c could be habitable – but just because the exoplanet is within a habitable zone, that doesn't necessarily mean it's one like Earth's.

The new data suggest that Wolf 1061c could have an atmosphere similar to what Venus had in its earliest days, meaning that any liquid water on the planet might not stick around for long. 

Previous research has suggested that high temperatures caused excessive water evaporation on Venus, and the newly formed water vapour in the atmosphere increased temperatures even further - a process known as a runaway greenhouse effect.

Now, the team thinks the same thing could be happening on Wolf 1061c, which is "close enough to the star that it's looking suspiciously like a runaway greenhouse", says Kane.

In addition, Wolf 1061c's orbit of its star varies much more quickly than Earth's orbit of the Sun, which would lead to chaotic climate changes such as a rapidly encroaching ice age (or warm phase).

So, is there life on Wolf 1061c?

We don't yet know, and to find out, we'll need more detailed measurements than what we have so far. To that end, Kane says NASA's James Webb telescope is one of the ways we'll be able to learn more about the exoplanet in the future.

Wolf 1061c Credit: Centauri Dreams

The telescope is launching next year, and its advanced optics should be able to reveal the atmospheric conditions on Wolf 1061c, and give us a better idea about whether water (and life) could really exist there.

Meanwhile, scientists from METI - the Messaging Extraterrestrial Intelligence organisation - are also interested in Wolf 1061c, and have been keeping a close eye on the exoplanet as they try to reach out to any alien life that might exist beyond our Solar System.

"I'm not holding my breath that we'll ever find evidence of life on Wolf 1061c," METI president Doug Vakoch told Rae Paoletta at Gizmodo.

"But the fact that there's a roughly Earth-like planet in the habitable zone of a star so close to our own Solar System is a good omen as we continue our search for life on other planets."

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Wednesday, December 14, 2016

Australian Radio Telescope Parkes Joins $100 Million Search for Alien Life

The Parkes radio telescope in Australia is the third telescope to begin searching for signs of intelligent alien life as part of the $100 million Breakthrough Listen project. Credit: CSIRO


Updated today 20/05/2020

$100 million search for intelligent alien life just added a big arrow to its quiver.

Breakthrough Listen has begun using the Parkes radio telescope in Australia to scan the heavens, representatives of the ambitious, decade-long project announced Monday (Nov.7).

Parkes, Narrabri radio telescopes to be upgraded to improve Space Connect


The Parkes dish becomes the third telescope to be employed by Breakthrough Listen, joining the Green Bank Telescope in West Virginia and the Automated Planet Finder at Lick Observatory in Northern California


"The addition of Parkes is an important milestone," billionaire entrepreneur Yuri Milner, founder of the Breakthrough Initiatives, which include Breakthrough Listen, said in a statement. "These major instruments are the ears of planet Earth, and now they are listening for signs of other civilizations."


The Parkes radio telescope can tilt 60° from vertical and would take 15 minutes to perform a 360° rotation. photo: wikipedia.org

The first Breakthrough Listen observations for the Parkes dish came Monday, when scientists turned the telescope toward the Proxima Centauri star system to look for possible signals from alien civilizations.


Proxima Centauri is the closest star to the sun, lying just 4.2 light-years away from Earth's star. This past August, astronomers announced the discovery of an Earth-size planet orbiting in Proxima Centauri's "habitable zone," the just-right range of distances where liquid water could exist on a world's surface.

It's therefore possible that the planet, known as Proxima b, may be capable of supporting life as we know it, scientists have said.



"The chances of any particular planet hosting intelligent life-forms are probably minuscule," Andrew Siemion, director of the University of California, Berkeley's SETI (Search for Extraterrestrial Intelligence) Research Center, said in the same statement.

"But once we knew there was a planet right next door, we had to ask the question, and it was a fitting first observation for Parkes," Siemion added. "To find a civilization just 4.2 light-years away would change everything."

Proxima Centauri is also the target of Breakthrough Starshot, a Breakthrough Initiatives effort that aims to blast tiny, sail-equipped "nanoprobes" toward the system at 20 percent the speed of light using powerful lasers. Milner and a group of researchers, including famed cosmologist Stephen Hawking, announced Breakthrough Listen in July 2015. Over the next 10 years, the $100 million endeavor aims to search the 1 million stars closest to the sun, as well as the 100 nearest galaxies to the Milky Way, for possible SETI signals.



The 210-foot-wide (64 meters) Parkes dish, which is operated by Australia's Commonwealth Scientific and Industrial Research Organization (CSIRO), lies near the town of Parkes, in the state of New South Wales. The radio telescope famously helped relay live video of the Apollo 11 moon landing back to Earth in July 1969, a role featured in the 2000 film "The Dish."

Breakthrough Listen representatives also announced last month that the project would be teaming up with China's new Five-hundred-meter Aperture Spherical radio Telescope (FAST) — the world's largest radio telescope — to coordinate SETI observations.


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Tuesday, December 13, 2016

Chandra X-Ray Observatory Recently discovered new SPT0346-52. Galaxy is undergoing an extraordinary boom of stellar construction, clues to universe’s evolution and big bang

The distorted galaxy in the simulation results from a collision between two galaxies, followed by them merging. Astronomers think such a merger could be the reason why SPT0346-52 is having such a boom of stellar construction. Once the two galaxies collide, gas near the center of the merged galaxy (shown as the bright region in the center of the simulation) is compressed, producing a burst of new stars. The composite inset shows X-ray data from Chandra (blue), short wavelength infrared data from Hubble (green), infrared light from Spitzer (red) at longer wavelengths, and infrared data from ALMA (magenta) at even longer wavelengths. (The light from SPT0346-52 is distorted and magnified by the gravity of an intervening galaxy, producing three elongated images in the ALMA data located near the center of the image. SPT0346-52 is not visible in the Hubble or Spitzer data, but the intervening galaxy causing the gravitational lensing is detected.) There is no blue at the center of the image, showing that Chandra did not detect any X-rays that could have signaled the presence of a growing black hole. Credit: Image courtesy of CXC Press Office.
A recently discovered galaxy is undergoing an extraordinary boom of stellar construction, revealed by a group of astronomers led by University of Florida graduate student Jingzhe Ma using NASA's Chandra X-Ray Observatory.

The galaxy known as SPT 0346‐52 is 12.7 billion light years from Earth, seen at a critical stage in the evolution of galaxies about a billion years after the Big Bang.

Chandra Overview NASA

Astronomers first discovered SPT 0346‐52 with the National Science Foundation's South Pole Telescope, then observed it with space and ground-based telescopes. Data from the NSF/ESO Atacama Large Millimeter/submillimeter Array in Chile revealed extremely bright infrared emission, suggesting that the galaxy is undergoing a tremendous burst of star birth.



South Pole Telescope - Wikipedia


SPT 0346-52 is part of a population of strong gravitationally-lensed galaxies photo: discovered Sci-News.com

However, an alternative explanation remained: Was much of the infrared emission instead caused by a rapidly growing supermassive black hole at the galaxy's center? Gas falling towards the black hole would become much hotter and brighter, causing surrounding dust and gas to glow in infrared light. To explore this possibility, researchers used NASA's Chandra X‐ray Observatory and CSIRO's Australia Telescope Compact Array, a radio telescope.

No X‐rays or radio waves were detected, so astronomers were able to rule out a black hole being responsible for most of the bright infrared light.

About Australia Telescope Compact Array - CSIRO

"We now know that this galaxy doesn't have a gorging black hole, but instead is shining brightly with the light from newborn stars," Ma said. "This gives us information about how galaxies and the stars within them evolve during some of the earliest times in the universe."

Stars are forming at a rate of about 4,500 times the mass of the Sun every year in SPT0346-52, one of the highest rates seen in a galaxy. This is in contrast to a galaxy like the Milky Way that only forms about one solar mass of new stars per year.

"Astronomers call galaxies with lots of star formation 'starburst' galaxies," said UF astronomy professor Anthony Gonzalez, who co-authored the study. "That term doesn't seem to do this galaxy justice, so we are calling it a 'hyper-starburst' galaxy."

The high rate of star formation implies that a large reservoir of cool gas in the galaxy is being converted into stars with unusually high efficiency.

Astronomers hope that by studying more galaxies like SPT0346‐52 they will learn more about the formation and growth of massive galaxies and the supermassive black holes at their centers.

"For decades, astronomers have known that supermassive black holes and the stars in their host galaxies grow together," said co-author Joaquin Vieira of the University of Illinois at Urbana‐Champaign. "Exactly why they do this is still a mystery. SPT0346-52 is interesting because we have observed an incredible burst of stars forming, and yet found no evidence for a growing supermassive black hole. We would really like to study this galaxy in greater detail and understand what triggered the star formation and how that affects the growth of the black hole."

Joaquin Vieira Wins Sloan Fellowship Astronomy at Illinois

SPT0346‐52 is part of a population of strong gravitationally-lensed galaxies discovered with the SPT. It appears about six times brighter than it would without gravitational lensing, which enables astronomers to see more details than would otherwise be possible.




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Wednesday, December 7, 2016

Young galaxies "born" at least 50 stars annually: These "incubators" within young galaxies annually produce more stars than was originally estimated

photo: nasa.gov





Young galaxies in the universe appear to be very fertile and, with an annual average of 50 new stars on the size of the sun.

Updated today 21/05/2020

The recent discovery shows as "incubators" within young galaxies annually produce more stars than was originally estimated. Astronomers have "traveled" back 12.5 billion years to study one of the most remote galaxies known MS1358arc known as infant Galaxies. Light began its journey in the universe just one billion years after the creation of the cosmos, from the Big Bang.
Stars formed at much faster rate in infant galaxies Brahmand News



Bubble Worlds" --Milky Way's Star The Daily Galaxy

The study of galaxy formation and evolution is concerned with the processes that formed a heterogeneous universe from a homogeneous beginning, the formation of the first galaxies, the way galaxies change over time, and the processes that have generated the variety of structures observed in nearby galaxies.


Galaxy SMM J2135-0102 wallpaper - Space wallpapers - #7263 SUWalls


Galaxy formation is hypothesized to occur, from structure formation theories, as a result of tiny quantum fluctuations in the aftermath of the Big Bang

The simplest model for this that is in general agreement with observed phenomena is the Λ-Cold Dark Matter cosmology; that is to say that clustering and merging is how galaxies gain in mass, and can also determine their shape and structure.


The dark side of cosmology: Dark matter and dark energy Science


Commonly observed properties of galaxies


Because of the inability to conduct experiments in outer space, the only way to “test” theories and models of galaxy evolution is to compare them with observations. Explanations for how galaxies formed and evolved must be able to predict the observed properties and types of galaxies.

Edwin Hubble created the first galaxy classification scheme known as the Hubble tuning-fork diagram. It partitioned galaxies into ellipticals, normal spirals, barred spirals (such as the Milky Way), and irregulars. These galaxy types exhibit the following properties which can be explained by current galaxy evolution theories:


Hubble tuning fork diagram of galaxy morphology photo: wikipedia.org

Many of the properties of galaxies (including the galaxy color–magnitude diagram) indicate that there are fundamentally two types of galaxies. These groups divide into blue star-forming galaxies that are more like spiral types, and red non-star forming galaxies that are more like elliptical galaxies.

Spiral galaxies are quite thin, dense, and rotate relatively fast, while the stars in elliptical galaxies have randomly-oriented orbits.
The majority of mass in galaxies is made up of dark matter, a substance which is not directly observable, and might not interact through any means except gravity.

The majority of giant galaxies contain a supermassive black hole in their centers, ranging in mass from millions to billions of times the mass of our Sun. The black hole mass is tied to the host galaxy bulge or spheroid mass.

Lenses open precision for 10bn-year-old galaxy - Compute Scotland

Metallicity has a positive correlation with the absolute magnitude (luminosity) of a galaxy.


Hubble thought incorrectly that the tuning fork diagram described an evolutionary sequence for galaxies, from elliptical galaxies through lenticulars to spiral galaxies. However, astronomers now believe that disk galaxies likely formed first, then evolved into elliptical galaxies through galaxy mergers.

So-called "gravitational lenses" were used to enlarge the galaxy using light how "fits" on a nearby star cluster. With this technique, the researchers could observe rapid ascent generated by the formation of new stars. Thus, they could conclude that new stars are created in the galaxy at a speed 100 times higher than the average forecast initially.

With a diameter of 6000 light-years, "collection" of stars will most likely evolve into a new spiral galaxy similar to the Milky Way.


Artist image of a firestorm of star birth deep inside core of young, growing elliptical galaxy. photo: wikipedia.org
Galaxy mergers and the formation of elliptical galaxies 

Elliptical galaxies (such as IC 1101) are among some of the largest known thus far. Their stars are on orbits that are randomly oriented within the galaxy (i.e. they are not rotating like disk galaxies). A distinguishing feature of elliptical galaxies is that the velocity of the stars does not necessarily contribute to flattening of the galaxy, such as in spiral galaxies. Elliptical galaxies have supermassive black holes at their center, and the mass of these black holes correlates with the galaxy’s mass.


NGC 4676 (Mice Galaxies) is an example of a present merger. photo: wikipedia.org

Elliptical galaxies have two main stages of evolution. The first is due to the supermassive black hole increasing in size from accreting cooling gas. The second stage is marked by the black hole stabilizing by suppressing gas cooling, thus leaving the elliptical galaxy in a stable state.The mass of the black hole is also correlated to a property called sigma which is the dispersion of the velocities of stars in the elliptical galaxies. 

This relationship, known as the M-sigma relation, was discovered in 2000. Elliptical galaxies do not have disks around them, although some bulges of disk galaxies look similar to elliptical galaxies. It is more likely to find elliptical galaxies in more crowded regions of the universe (such as galaxy clusters).
Antennae Galaxies are a pair of colliding galaxies - the bright, blue knots are young stars that have recently ignited as a result of the merger. photo: wikipedia.org


Astronomers now see elliptical galaxies as some of the most evolved systems in the universe. It is widely accepted that the main driving force for the evolution of elliptical galaxies is mergers of smaller galaxies. Many galaxies in the universe are gravitationally bound to other galaxies, which means that they will never escape the pull of the other galaxy. 
ESO 325-G004, a typical elliptical galaxy. photo: wikipedia.org

If the galaxies are of similar size, the resultant galaxy will appear similar to neither of the two galaxies merging,but will instead be an elliptical galaxy. There are many types of galaxy mergers, which do not necessarily result in elliptical galaxies, but result in a change in the structure of the mergers. For example, a minor merger event is thought to be occurring between the Milky Way and the Magellanic Clouds.



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Monday, October 3, 2016

The First Stars in the Universe could provide clues about Dark Matter

Photo : softpedia.com

The first stars appeared in the Universe which might contain clues to provide more explanations about the origin of dark matter, a substance that still retains its mysteries, 70 years after it was discovered by researchers, informs AFP.

Based on mathematical models created on your computer, researchers at the University of Durham, UK, concluded that dark matter, which is of two types, "hot" and "cold" was essential to the formation of the first stars in the Universe .

Photo:  softpedia.com
Shortly after the Big Bang, which occurred 13.7 billion years ago, matter which form when the Universe was smooth as the surface of a river, with a few small undulations. These undulations extended under the effect of gravity which act on dark matter particles contained. Between these particles penetrated gas, and in this process occurred first stars, about 100 million years after the Big Bang, according to the researchers.

British experts say that a large number of stars of different sizes so the vast explosions occurred simultaneously resemble long filaments, which suddenly became incandescent.

Stellar Evolution Photo: physics.stackexchange.com

Liang Gao, one of the co-authors of the study, explained that "these filaments of measurements about 9,000 light years, or a quarter of the length of the Milky Way" galaxy of which the Earth.

Stars born in such dark matter "hot" with a lower density, should still exist in the Milky Way and their analysis should provide clues to unravel the mysteries of dark matter, according to astro-physicists.

Instead, the first stars formed from dark matter particles "cold" were denser and could not survive as much as those formed from matter "hot", according to the mathematical model devised by researchers.

US astronomers announced in May that they had uncovered a ring of dark matter in a galaxy cluster, which is probably the most important so far this mysterious substance that forms over a fifth of the universe.

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It was created the most complex map of the Milky Way . It shows that our galaxy is much more extensive than previously thought

Milky Way  (Foto:spaceandintelligence.com) 
Researchers say they underestimated the number of stars existing within our galaxy.

European Space Agency released the most detailed map to date of the Milky Way. The digital representation depicting the positions of no less than 1.142 billion stars, is the first product of Gaia space observatory, launched three years ago. Among the identified cosmic objects there were about 400 million stars unknown, which means that our galaxy is much more extensive than previously thought in the moment.

,, This map released today the extraordinary density of the stars studied by Gaia indicates and confirms that space observatory has collected valuable information in its first year of activity. Although current data are preliminary, we will do our best to put them to the community of astronomers to use them as soon as possible, "says Timo Prussia, a researcher involved in the project Gaia.

Map presented by the European Space Agency experts is the result of the cumulative effort of not less than 450 researchers. Comparing observations with the help of Gaia observer to those shown in the Hipparcos and Tycho catalogs-2, scientists have been able to estimate distances and movements carried about 2 million stars. The result: the most comprehensive picture of the movement of the stars obtained so far.

Map Milky Way obtained by European astronomers (Photo: sciencealert.com/ESA/Gaia/DPAC)
Gaia Space Observatory is located about 1.5 million kilometers from Earth and is equipped with a 1 miliiard pixels capable of measuring the diameter of a human hair from a distance of 1,000 kilometers. Vehicle mission will last nearly 5 years and aims at mapping the Milky Way, which astronomers assume that accommodates no less than 100 billion stars.

Although experts are confident that the Centre will not be able to analyze these cosmic objects over 5 years, they say, for now, the result is very good, given that Gaia has begun to map the proper since July 2014.


,, It appears we underestimated the number of stars. We think there are about 2-2.5 billion, "said van Leeuwen Floor, researcher at Cambridge University.

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Friday, September 2, 2016

An unusual signal was obtained by Russian astronomers. It may have extraterrestrial origins

Signal is not very different from that used for digital television.

Astronomers have detected a burst of energy last year appeared to his level HD 164 595, a star located at a distance of about 94 light-years from Earth towards the constellation Hercules. This phenomenon was observed by Russian radiotelescope Ratan-600 and immediately aroused the interest of researchers seeking to prove the existence of extraterrestrial life.

,, An international team of researchers announced detection of a strong signal came from the direction of HD164595. Nobody claimed it was caused by an extraterrestrial civilization, but the signal is so obvious that specialists operating Ratan-600 want the target to be monitored further, "says American author Paul Gilster his blog,, Centauri Dreams" .

The signal HD 164595 (Foto:sciencealert.com/C. Maccone et al./Centauri Dreams)
Seth Shostak, an astronomer at the SETI Institute (Search for extraterrestrial intelligence), says that his team has recently tried again to detect the signal issued on 15 May 2015, but found nothing. Both Shostak and Gilster obtained information about the new discovery of the Italian astronomer Claudio Maccone, who collaborated with Russian researchers when they used the telescope Ratan-600.

Maccone Published results were analyzed by specialists. They argue that, in the event that they will prove to be true, would indicate the presence of signals from a star similar to the sun because it has a smaller table with only 1% to it, is younger by 100 million years, it has a similar temperature and, moreover, has a similar chemical composition.

During the research, astronomers have discovered a planet similar to Neptune orbiting the star HD 164595. that she was named ,, HD 164 595 ", and experts say it is possible that other cosmic objects of this kind exist in the area, but not have been detected until now.


Russian Astronomers are particularly fascinated by showing how the signal emitted by the star. He has a wavelength of about 2.7 centimeters and a frequency of 11 GHz, which means it is a very high frequency signal not very different from that used for digital television. Shostak argues that if it was real, the signal must have been extremely powerful to be detected on Earth.

The radio telescope Ratan-600 (Photo: sciencealert.com/александр с кавказа / Wikimedia)
Researcher at the SETI Institute clearly exclude the possibility that the signal had extraterrestrial origin. Specialist argues, first, that their astronomers had more than one year up to give early information about the signal they detected. Secondly, Ratan-600 radio telescope works with an error that does not allow him to ascertain with certainty whether the signal comes from a star system similar to that in the center of which is HD 164595. Moreover, the signal is so vast that is extremely difficult to verify.


SETI specialists will try again to find the new signals from HD 164 595, but expects first Maccone and Russian astronomers to publish their findings formally. Until then, the only hypothesis that American astronomers take still considering is the fact that the signals were emitted lens gravitational what would have been formed when the star HD 164 595 concentrated around its material universe.

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Source: sciencealert.com 

Tuesday, August 9, 2016

KIC 8462852 Alien structure in our galaxy?

One of the most unusual stars in our galaxy, KIC 8462852, is astronomical attention in recent months.

The star is 1,480 light years away from our planet. This sparked the interest of researchers in October when they were discovered unusual fluctuations of light.

In the new study has found that light intensity has decreased dramatically in recent days. Astronomers Montet Ben and Joshua Simon from the Carnegie Institution have discovered the star's light intensity measured by Kepler during the fourth mission. In the early years, the light intensity was decreased by 0.34% each year. Then intensity dropped dramatically, by 2.5% in 200 days, before returning to its intensity bland.

Tabby's Star - Wikipedia

Astronomers have investigated another 500 stars in its neighborhood, but found none like this. ,, The part that surprised us was how quickly and how that change nonlinear. We spent a long time convincing us that it is not real, '' said Montet.

'' These results show a new part of the puzzle impressive ment, '' said the r \ ndul they Tabetha Boyajian. In some theories, it was suggested that decreasing light intensity is caused by a mega alien. The project started on May 18 by the researcher at Yale University, Tabetha Boyajian, accumulated investment amount of $ 100,000 This project aims to investigate the mysterious stars in the galaxy.

Kepler probe monitored the star for four years, assisting in two dramatic incidents in 2011 and 2013, when starlight fell dramatically. When a planet orbits a star, its brightness decreases by one percent. But KIC 8462852, nicknamed Tabby's star, suffered a 22% reduction, which means that a huge object moves around them.

The most remarkable aspect of these fluctuations is made up of hundreds of light gaps that occur over a period of 100 days, indicating that an impressive number of irregular objects passed before the star and blocked temporarily light.


Researchers monitored the star to see what objects produce these forms ..

One of their theories relate to or more satellites or solar panels which surround a star formation known as a Dyson swarm. In a study in which they use information collected by NASA's Spitzer Telescope it was suggested that changing light intensity can be affected by a swarm of comets. In a study published last month it has been stated that the signals are caused by Halley's comet breaking 30 who blocked the starlight.

Observations researchers will continue, but so far no evidence has been found to decrease the brightness deliberately.


Source: dailymail

Tuesday, July 26, 2016

Dark Energy vs. Dark Matter: What The Universe is Made Of



Dark Energy vs. Dark Matter

While dark energy repels, dark matter attracts. And dark matter’s influence shows up even in individual galaxies, while dark energy acts only on the scale of the entire universe

Our universe may contain 100 billion galaxies, each with billions of stars, great clouds of gas and dust, and perhaps scads of planets and moons and other little bits of cosmic flotsam. The stars produce an abundance of energy, from radio waves to X-rays, which streak across the universe at the speed of light.

Yet everything that we can see is like the tip of the cosmic iceberg — it accounts for only about four percent of the total mass and energy in the universe.



About one-quarter of the universe consists of dark matter, which releases no detectable energy, but which exerts a gravitational pull on all the visible matter in the universe.

Because of the names, it’s easy to confuse dark matter and dark energy. And while they may be related, their effects are quite different. In brief, dark matter attracts, dark energy repels. While dark matter pulls matter inward, dark energy pushes it outward. Also, while dark energy shows itself only on the largest cosmic scale, dark matter exerts its influence on individual galaxies as well as the universe at large.

In fact, astronomers discovered dark matter while studying the outer regions of our galaxy, the Milky Way.


A ring of possible dark matter highlights this Hubble Space Telescope image of a distant galaxy cluster. [NASA/ESA/M.J. Jee/H. Ford (Johns Hopkins)]

The Milky Way is shaped like a disk that is about 100,000 light-years across. The stars in this disk all orbit the center of the galaxy. The laws of gravity say that the stars that are closest to the center of the galaxy — which is also its center of mass — should move faster than those out on the galaxy’s edge.

Yet when astronomers measured stars all across the galaxy, they found that they all orbit the center of the galaxy at about the same speed. This suggests that something outside the galaxy’s disk is tugging at the stars: dark matter.

Calculations show that a vast "halo" of dark matter surrounds the Milky Way. The halo may be 10 times as massive as the bright disk, so it exerts a strong gravitational pull.

The same effect is seen in many other galaxies. And clusters of galaxies show exactly the same thing — their gravity is far stronger than the combined pull of all their visible stars and gas clouds.

Scientists shed light on mystery of dark matter HeritageDaily


Are dark matter and dark energy related? No one knows. The leading theory says that dark matter consists of a type of subatomic particle that has not yet been detected, although upcoming experiments with the world’s most powerful particle accelerator may reveal its presence. Dark energy may have its own particle, although there is little evidence of one.

Instead, dark matter and dark energy appear to be competing forces in our universe. The only things they seem to have in common is that both were forged in the Big Bang, and both remain mysterious.











































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Source: hetdex