Tag Archives: milky way galaxy

An artist's impression of a collision between the Milky Way and a smaller dwarf galaxy, such as that which occurred about eight to 10 billion years agoV. Belokurov (Cambridge, UK) based on an image by ESO/Juan Carlos Muñoz)

A dwarf galaxy may have collided with the Milky Way 3 billion years ago

Over twenty years ago astronomers first observed an unusually high density of stars in the vicinity of the Virgo cluster with the Milky Way, but until now the cause of the so-called Virgo Overdensity was unknown. New research suggests that this overdensity was actually caused by a dwarf galaxy plugging into the heart of the Milky Way over 3 billion years ago. But unlike in folklore when a wooden stake plunges through the heart of a vampire, it was this cosmic impaler that was destroyed by the interaction. 

The gravitational influence of the Milky Way ripped the dwarf galaxy apart leaving behind telltale shell-like formations of stars as the only evidence of the violent collision. Evidence that has now been uncovered by astronomers.

Two spiral galaxies (from left) NGC 2207 and IC 2163 colliding with one another. Credit: NASA.

“When we put it together, it was an ‘aha’ moment. This group of stars had a whole bunch of different velocities, which was very strange,” says Heidi Jo Newberg, the Rensselaer Institute professor of physics, applied physics, and astronomy, who led the team that made the discovery. “Now that we see their motion as a whole, we understand why the velocities are different, and why they are moving the way that they are.”

The team’s research is published in the latest edition of The Astrophysical Journal. They detail two shell-like structures in the Virgo Overdensity and a further pair in Hercules Aquila Cloud region. Their findings are based on data provided by the Sloan Digital Sky Survey, the European Space Agency’s Gaia space telescope, and the LAMOST telescope in China.

The Virgo Overdensity: Evidence of a Cosmic Collision

The Virgo Overdensity has, until now, been something of an oddity amongst such clusters. Star surveys have revealed that some of the stars that make up the Virgo Overdensity are moving toward us, whilst others are moving away. This is behaviour that would not normally be seen in a cluster of this kind. In 2019, researchers from the Rensselaer Institute had put forward the idea that this is because the overdensity is a result of a radial — or T-bone — collision.

The shell structures described in this new study — not observed before–seems to confirm this origin for the Virgo Overdensity. These arcs of stars — curved like umbrellas — are believed by the team to be the what remains of the dwarf galaxy after it was pulled apart by the Milky Way’s overpowering gravitational influence. 

an N-body simulation of a radial merger between the Milky Way Galaxy and a dwarf galaxy. Collisions like these create what are known as “shells” in the Galaxy’s halo (Thomas Donlon)

The process caused the dwarf galaxy to ‘bounce’ through the centre of the Milky Way with its stars being gradually incorporated into our galaxy. Each time the dwarf galaxy passed through the Milky Way’s centre the stars would initially move quickly, gradually being slowed by the gravity of our galaxy, until this influence eventually pulls them back. Each time the dwarf galaxy ‘threaded back’ through the centre a new shell was created. 

Counting the number of shells allowed the team to calculate how many cycles the dwarf galaxy has undergone which in turn allows them to estimate how many years it has been since the collision — which they are naming the ‘Virgo Radial Merger’ —  took place. Thus the team dates the first passage of the dwarf galaxy through the centre of the Milky Way at 2.7 billion years ago. 

The Immigrant’s Song

Lead author Newberg believes that the majority of the stars in the Milky Way’s halo — a spherical cloud of stellar bodies that surround our galaxy’s spiral arms — appear to be ‘immigrants’ that formed in smaller galaxies and deposited by collisions different from the radial merger described above. 

The researcher, who specialises in the Milky Way’s stellar halo, says that as dwarf galaxies were absorbed into the Milky Way, ensuing tidal forces pulled their stars into long cords moving in unison through the halo. These are so-called tidal mergers which are both less violent and far more common than radial collisions. 

The fact that radial mergers are uncommon means the team was slightly taken back by the discovery of such evidence in the centre of the Milky Way. It was only as the team began to model the movement of the Virgo Overdensity that the significance of their discovery began to dawn on them. 

The Gaia Sausage–the team’s findings imply this colourfully named cluster of stars was not created in the same event that created the Virgo Overdensity, or that it is much younger than previously believed (ESA/Gaia. this image was prepared by Edmund Serpell, a Gaia Operations Engineer working in the Mission Operations Centre at ESA’s European Space Operations Centre in Darmstadt, Germany. CC by SA 3.0)

“There are other galaxies, typically more spherical galaxies, that have a very pronounced shell structure, so you know that these things happen, but we’ve looked in the Milky Way and hadn’t seen really obvious gigantic shells,” explains Thomas Donlon II, a Rensselaer graduate student and first author of the paper. “And then we realized that it’s the same type of merger that causes these big shells. It just looks different because, for one thing, we’re inside the Milky Way, so we have a different perspective, and also this is a disk galaxy and we don’t have as many examples of shell structures in disk galaxies.”

In addition to pointing towards the radial collision almost 3 billion years ago, the team’s research has potential implications for other stellar phenomena. In particular, the findings indicate that the ‘Gaia Sausage’ — a formation that astronomers believe is the result of a collision with a dwarf galaxy between 8 and 11 billion years ago — was not created by the same event that created the Virgo Overdesity, as scientists had previously believed.

The team’s findings clearly imply that the Virgo Overdensity is much younger than the Gaia Sausage meaning that the two had different origins, or that the colourfully named ‘sausage’ is fresher than previously believed. This would also mean that it could not have caused the thick central disc stars at the centre of the Milky Way.

“There are lots of potential tie-ins to this finding,” concludes Newberg. “The Virgo Radial Merger opens the door to a greater understanding of other phenomena that we see and don’t fully understand, and that could very well have been affected by something having fallen right through the middle of the galaxy less than 3 billion years ago.”

Astronomers map the Local Void – the huge “nothingness” surrounding the Milky Way

The local void — a vast cosmic structure surrounding our Milky Way galaxy — has been mapped in a new study, suggesting why our galaxy doesn’t travel with the expansion of the universe.

The large-scale structure of the universe is a tapestry of congregations of galaxies and vast voids. Applying same tools from an earlier study, Brent Tully from the University of Hawaii and his international team of astronomers have been able to map the size and shape of an extensive empty region they called the Local Void that borders the Milky Way galaxy.

Shaded grey contours outline the extent of the Local Void, while blue dots show major mass constituents (large galaxies, galaxy groups, and clusters). The curved blue lines show the derived motions of these massive objects, after removing the overall expansion of the universe. The most important galaxy congregations are given special symbols, like the red ball identifying the Virgo Cluster. The dominant pattern of motions revealed by the orbits is a flow away from the Local Void. (University of Hawaii)

Shaded grey contours outline the extent of the Local Void, while blue dots show major mass constituents (large galaxies, galaxy groups, and clusters). The curved blue lines show the derived motions of these massive objects, after removing the overall expansion of the universe. The most important galaxy congregations are given special symbols, like the red ball identifying the Virgo Cluster. The dominant pattern of motions revealed by the orbits is a flow away from the Local Void. Credits: University of Hawaii.

Tully and his team were able to measure the motions of 18,000 galaxies in the Cosmicflows-3 compendium of galaxy distances. This allowed them to build a 3D cosmographic map that highlighting the boundary between the collection of matter and the absence of matter. This boundary defining the edge of the Local Void.

The team used the same technique to identify the full extent of our home supercluster of over one hundred thousand galaxies in 2014, giving it the name Laniakea — or “immense heaven” in Hawaiian.

For 30 years, astronomers have been trying to identify why the motions of the Milky Way, our nearest large galaxy neighbour Andromeda, and their smaller neighbours deviate from the overall expansion of the Universe by over 600 km/s (1.3 million mph).

This new study — published in The Astrophysical Journal — shows that roughly half of this motion is generated “locally” from the combination of a pull from the massive nearby Virgo Cluster and our participation in the expansion of the Local Void as it becomes ever emptier.

Studying the local void

Galaxies not only move with the overall expansion of the universe — or the Hubble Flow — but they also respond to the gravitational influence of their neighbours and regions with an abundance of mass.

A smoothed rendition of the structure surrounding the Local Void. Our Milky Way galaxy lies at the origin of the red-green-blue orientation arrows (each 200 million lightyears in length). We are at a boundary between a large, low-density void, and the high-density Virgo cluster. (University of Hawaii)

A smoothed rendition of the structure surrounding the Local Void. Our Milky Way galaxy lies at the origin of the red-green-blue orientation arrows (each 200 million lightyears in length). We are at a boundary between a large, low-density void, and the high-density Virgo cluster. (University of Hawaii).

 As a consequence, relative to the Hubble Flow they are moving towards the densest areas and away from regions with little mass — the voids.

The knowledge that our Milky Way galaxy is at the edge of an extensive empty region that they called the Local Void dates back to research spearheaded by Tully and Richard Fisher in 1987.

Despite the fact that the existence of the Local Void has been widely accepted, it has remained poorly studied until now, because it lies behind the centre of our galaxy. This means it heavily obscured from our view by gas and dust lying in the galaxy’s equatorial plane.

In addition to a video showing the simulations the team created, the astronomers have also provided the public with a resource that enables them to manipulate their view of the local void.

You can find that program here.


*Something* is blasting “cosmic bullet holes” through our galaxy

We don’t know what it is. We don’t even know if it’s made of regular matter — but we do know that something blasted a series of holes through some stars in the Milky Way.

“It’s a dense bullet of something,” said Ana Bonaca, a researcher at the Harvard-Smithsonian Center for Astrophysics, who discovered evidence of the impactor.

Bonaca analyzed a series of stars called GD-1 — a very long, thin, Milky Way star stream. GD-1 stars have been studied ever since they were discovered in 2006, and Bonaca has been using data from the recently launched Gaia telescope to analyze them in more detail, finding something bizarre smack in the middle of the stream.

This type of stellar stream is created by the tidal (gravitational) force of the Milky Way, which bends and stretches the stream, producing a gap about midway through the stream.

But when Bonaca looked at GD-1 more recently, she found a second gap — and a weird one at that. The second gap is not smooth as the first one but has a ragged edge — as if something was shot through it.

“It’s a dense bullet of something,” Bonaca said.

The “bullet” would have to be something absolutely massive, much bigger than a star, and more massive than all but the largest of black holes. It’s not out of the question for a supermassive black hole to be the culprit, but if this is the case, it would have to be one at the scale of the supermassive black hole at the center of our galaxy. There isn’t a clear reason why such a black hole would exist towards the edge of our galaxy, and astronomers haven’t seen any effects from it.

This leaves another tantalizing possibility: a massive object made of dark matter.

Dark matter is a hypothetical form of matter that is thought to account for approximately 85% of the matter in the universe and about a quarter of its total energy density. We don’t know what dark matter is and we’ve never seen it — but we have seen its effects, and astronomers are quite confident that it exists. We also have no idea how dark matter might be distributed through the universe — is it thin and diffusive, or large and clumpy? If dark matter was indeed shot through GD-1 stars, it would suggest the latter. However, a large ball of dark matter is still speculative at this point, although it seems to line up with the evidence quite nicely.

The results have not yet been peer-reviewed, though they were met positively at the conference of the American Physical Society in Denver where they were presented.

At this point, the turbulent history of GD-1 stars just isn’t established well enough to draw a definite conclusion. But whatever it is, is Bonaca’s hypothesis is true, something shot a massive “bullet” straight through our galaxy — and we don’t know what it is.

We’re living in the Milky Way, version 2.0

A new tantalizing study suggests that the Milky Way galaxy died over 7 billion years ago — only to come back to life in a different epoch.

As far as galaxies go, the Milky Way seems pretty average: it’s a barred spiral galaxy with a diameter between 150,000 and 200,000 light years, containing somewhere between 100 and 400 billion stars. Shockingly high numbers but again, pretty average for a galaxy.

But what makes the Milky Way special, at least as far as we’re concerned, is that somewhere, on one of its spiral arms, there’s a solar system orbiting around a dwarf star; and in that solar system, there’s a planet mostly covered by water, where intelligent life has evolved in the form of primates. Now, some of these primates have learned that the Milky Way itself might not be all that average: it seems to have been born twice.

The key of the new study lies in the chemical make-up of Milky Way stars. Their chemical compositions can reveal information about the gasses from which they formed, providing important clues regarding the history of their galactic neighborhood. Masafumi Noguchi of Tohoku University in Sendai, Japan, proposes that stars in our galaxy were formed in two distinct epochs. He analyzed so-called alpha process elements (or α-elements) such as oxygen, magnesium, and silicon, thanks to a process called cold flow accretion. Some 10 billion years ago, when the universe was still in its early stages, stars contained significant amounts of these gases — and researchers can now analyze them to date cosmic objects, somewhat like tree rings record the age of a tree.

These early stars tended to end in massive but short-lived supernova explosions. These supernovae explosions were also rich with these α-elements but after a while, but they were so hot that they prevented cold flow accretion throughout the galaxy, stopping the new gas from flowing into the galaxy and forming new stars. This hiatus for about 3 billion years, when a new generation of stars began to form — but unlike the old one, this one was rich in iron. So the Milky Way entered a state of dormancy — essentially, it died, only to be reborn once again some 5 billion years later.

Credits: M. Noguchi / Nature.

The existence of two distinct groups of stars in the solar neighborhood, one with high [α/Fe] and the other with low [α/Fe], suggests two different origins

According to Benjamin Williams from the University of Washington, who wasn’t involved in this study, our neighbor galaxy, Andromeda, also formed stars in two separate epochs. Noguchi proposes a model that can explain this phenomenon and predicts that massive spiral galaxies like the Milky Way and Andromeda experience a gap in star formation, whereas smaller galaxies made stars continuously.

However, the exact mechanism underlying this phenomenon isn’t well understood, and Noguchi calls for future observations of nearby galaxies, which he says “may revolutionize our view about galaxy formation.”

The study was published in Nature.

A 12-year study of massive stars has reaffirmed that our Galaxy has four spiral arms, following years of debate sparked by images taken by NASA’s Spitzer Space Telescope that only showed two arms. (c) University of Leeds

The Milky Way grows back two spiral arms

There has been a debate over the number of spiral arms the Milky Way galaxies has, due to mixed results in the past. For years, it was believed the Milky Way had four spiral arms, but in 2008 readings from the Spitzer Space Telescope suggested it actually had only two. Wouldn’t you know it, a new study that looked at young and massive star found that the Milky Way must have four arms.

Four arms, not two, survey suggests

From our perspective, it’s impossible to simply pan out and have a view of how the Milky Way looks like. Most certainly you’ve seen quite a couple of beautiful renditions of the Milky Way – most of which with two spiral arms – however these are all artist impressions. Simple computer generated graphics based on scientists’ description. Raw data is everything we have at the moment to interpret the size, shape and structure of our very own galaxy.

A 12-year study of massive stars has reaffirmed that our Galaxy has four spiral arms, following years of debate sparked by images taken by NASA’s Spitzer Space Telescope that only showed two arms. (c) University of Leeds

A 12-year study of massive stars has reaffirmed that our Galaxy has four spiral arms, following years of debate sparked by images taken by NASA’s Spitzer Space Telescope that only showed two arms. (c) University of Leeds

James Urquhart at the Max Planck Institute for Radio Astronomy in Bonn, Germany and team recently performed a survey of massive stars from the Milky Way. Since massive stars fly high and die fast  – they only last for some 10 million years or so – meaning that they are only found in the arms in which they formed, which could explain the discrepancy in the number of galactic arms that different research teams have claimed. The controversial 2008 Spitzer survey analyzed some 110 million stars, most of which were cooler, lower-mass stars – stars like our sun. These are much more numerous than the massive and bright stars targeted by the present study.

 “It’s exciting that we are able to use the distribution of young massive stars to probe the structure of the Milky Way and match the most intense region of star formation with a model with four spiral arms,” said Urquhart.

Several radio telescopes in Australia, the U.S. and China were used to observe about 1,650 massive stars over the course of 12 years. Scientists calculated the distances and luminosities between them and came up with a spatial distribution that suggests a four spiral arm galaxy.

“Star formation researchers, like me, grew up with the idea that our galaxy has four spiral arms. It’s great that we have been able to reaffirm that picture,” said astronomer Melvin Hoare at the University of Leeds, a co-author of the research paper.

Findings were reported in a paper published in the Monthly Notices of the Royal Astronomical Society.

An infrared image of the Lobster nebula, filled with glowing clouds of gas and tendrils of dust surrounding hot young stars. (c) ESO

Lobster nebula shines in new light after infrared observation

An infrared image of the Lobster nebula, filled with glowing clouds of gas and tendrils of dust surrounding hot young stars. (c) ESO

An infrared image of the Lobster nebula, filled with glowing clouds of gas and tendrils of dust surrounding hot young stars. (c) ESO

Deep inside the Milky Way lies the beautiful star breeding ground known as the Lobster nebula, located in the constellation Scorpius – some 8,000 light-years away from Earth. The nebula has been the subject of study for astronomers for many years, however just recently it has been imaged in infrared for the first time capturing its beauty in a whole new light.

The ESO’s Visible and Infrared Survey Telescope for Astronomy (VISTA)  at the Paranal Observatory in Chile is  the largest and most powerful survey telescope ever built. It’s task is that of scanning the Milky Way as part of a major effort to map our galaxy’s structure and learn how it formed.

Part of this survey, the Lobster nebula, known to astronomers by the name of NGC 6357, was also scanned. Being a nebula, naturally a lot of it is obscured to optical observations due to the massive clouds of dust that surround it on all planes. This new infrared observation has now revealed a myriad of new elements hidden before, like  tendrils of purple gas that stretch out from the nebula in different areas.

Besides being a pretty picture, the Lobster nebula actually presents some unique characteristics. For one, the nebula is home to the Pismis-24 star cluster, which contains some of the most massive stars in the Milky Way. Nevertheless, the Lobster nebula joins countless other nebulae, clusters, and various cosmic bodies as part of the massive VISTA survey which intends to eventually build a huge dataset capable that might hint to the origin, early life, and structure of the Milky Way.

As an added bonus, ESO has also provided a stunning video that zooms in on the Scorpius constellation and beautifully lands the viewer gently at the heart of the nebula.

This highly distorted supernova remnant may contain the most recent black hole formed in the Milky Way galaxy. The composite image combines X-rays from Chandra (blue and green), radio data from the Very Large Array (pink), and infrared data from the Palomar Observatory (yellow). (c) NASA

Rare supernova leftovers might have produced the youngest black hole in the Milky Way

This highly distorted supernova remnant may contain the most recent black hole formed in the Milky Way galaxy. The composite image combines X-rays from Chandra (blue and green), radio data from the Very Large Array (pink), and infrared data from the Palomar Observatory (yellow). (c) NASA

This highly distorted supernova remnant may contain the most recent black hole formed in the Milky Way galaxy. The composite image combines X-rays from Chandra (blue and green), radio data from the Very Large Array (pink), and infrared data from the Palomar Observatory (yellow). (c) NASA

Astronomers at NASA‘s Chandra X-ray Observatory were delighted to come across one of the rarest events in the Universe, after they came across an atypical kind of supernova. To top it over, the supernova’s remnants may have given birth to the Milky Way’s youngest black hole estimated thus far.

After a massive star, say ten times more massive than our own sun, dies, it explodes spilling its contents through out space – a highly energetic event called a supernova. Typically remnants are symmetrical, bursting outward in an ever-expanding bubble. However, the supernova discovered by the NASA astronomers, called W49B and located some  26,000 light-years away, doesn’t quite fit the pattern.

Scientists found that the supernova ejects matter in an asymmetrical manner, shooting off material near its poles at a much higher speed than from elsewhere on its surface. Also, its chemical concentration has also been found to be asymmetrical only half of the remnants showed concentrations of iron, while sulfur and silicon were spread evenly throughout the explosion – another sign that W49B is not your usual nugget.

Actually, this kind of supernova is so rare that it’s the first ever discovered in our galaxy. Get ready for a kicker, though, since W49B is a real super star… or used to be at least.

Based on the information astronomers have gathered thus far, actually the lack of information for that matter, they believe  a black hole may have formed. Such massive stars like the one that sparked the W49B supernova typically leave behind neutron stars — heavy, compact objects that emit  X-rays or radio pulses. No such signals were detected, however, which gave rise to the conclusion.

Now, considering was W49B and was created 1,000 years ago, it would mean that this potential black hole is the youngest in the Milky Way.

Doomsday part 5: Planetary and galactic alignment

mayan-doomsday-special-zmescience

On December 21 the solar system’s planets will align and/or the sun will also align in turn with the center of the Milky Way Galaxy, which only happens once every 25,772 years, coincidentally with the end of the 13th Bak’tun in the Maya Long Count calendar (December 21st, 2012). The Maya having a superior astronomical knowledge that surpassed that of today knew that this event will happen and thus set their Long Count calendar to end on this day because the alignment will cause something to happen.

Reality check 

Our galaxy, the Milky Way, is like a disk 100,000 light-years across and 1,000 light-years thick. At its center, like in the case of most galaxies, lies a supermassive black hole that tugs all the other stars and satellite galaxies around it. First of all, the sun and the Milky Way’s core can be seen as two geometric points, and as such when connecting the two they will always be aligned, no matter what position the two might be relative from one another. It’s simple common sense. However, if we throw in the Earth into the mix, then a three way alignment of our planet, the sun and Milky Way black hole, is a whole different matter. I won’t go into the details of what consequences might ensue as a result of this alignment (little to any), it’s suffice to say that such a galactic alignment is extremely rare, and by no means will it occur on December 21. The next such alignment will happen in 4 million years.

Regarding an eventual planetary alignment within our solar system, I’ll leave this to NASA:

There are no planetary alignments in the next few decades and even if these alignments were to occur, their effects on the Earth would be negligible. One major alignment occurred in 1962, for example, and two others happened during 1982 and 2000. Each December the Earth and sun align with the approximate center of the Milky Way Galaxy but that is an annual event of no consequence.

Read about other popular Mayan doomsday “prophecies” from our debunking series:

Milky Way Satellite Galaxies

The Milky Way’s mass is 1,6 trillion suns, far more than previously estimated

Milky Way galaxy

In a novel and highly praised research, a team of astronomers have managed to estimate the mass of our host galaxy with unprecedented accuracy, findings suggesting it is in the order of 1,6 trillion suns.

Astronomers estimate there are between 200 and 400 billion stars in the milky way. Estimating the mass of the Milky Way solely based on star masses would make it an easy task, however there are many more entities besides stars that contribute to the galaxy’s mass, hampering research to a sluggish extent. For one, the Milky Way, like any other galaxy, is covered in a dark halo of matter which far outweighs the collective constitutive stars. Since this halo is invisible, calculations are very difficult to be made.

By harnessing an extremely ingenious method, however, Sangmo Tony Sohn of the Space Telescope Science Institute and colleagues were able to provide a widely accepted estimate of the Milky Way’s mass by studying one of its most outer orbiting satellite galaxies. The Milky Way has two dozen or so satellite galaxies that orbit the supermassive blackhole lying at its center. By studying the orbits of these satellite galaxies, including its velocity and radius, scientists can infer the mass of both the satellite and host galaxy.

The prime study candidate is the satellite galaxy “Leo I”, which is the most distant located some 850,000 light-years from the Milky Way’s center, while also moving extremely fast. These two characteristics made it an ideal object to study, since being the farthest satellite galaxy, it fits all of the Milky Way’s dark halo inside its orbit. If it’s a satellite galaxy in the first place, that is. And exactly here, in this rather tricky judgement call, that the technique allows for mass inference. If the Milky Way has enough mass, then Leo I will indeed orbit it, if not then Leo I isn’t a satellite and is just …passing by.

Milky Way Satellite Galaxies

A diagram of the known Milky Way satellites and their orbits. Detailed information can be found here.

In order to deduce Leo I’s path through space, the scientists first determined its Doppler shift – indicating a forward or backward motion along our line of sight – however they then had to determine its proper motion as well —the change in the galaxy’s position from one year to the next. To this end, Sohn and colleagues used the Hubble Space Telescope to compare Leo I’s position in 2006 and 2011 with more than a hundred background galaxies.

Milky Way: a hefty lady

Finally, the researchers were able to estimate that Leo I orbits the Milky Way at 200 kilometers per second, which is roughly comparable with the velocity of our own sun orbiting the Milky Way’s center, only Leo I is 30 times the distance farther. To sustain such a velocity at such a distance requires a lot of extra mass.

“It’s a powerful piece of work,” says Timothy Beers, the director of Kitt Peak National Observatory, who was not affiliated with the research. “It strikes me as utterly amazing that we have instruments that can measure proper motions that far away.” Scott Tremaine, an astronomer at the Institute for Advanced Study, agrees: “The measurement of the proper motion really is a tour de force.”

To find out how much extra mass exactly would be required, an accompany study lead by Michael Boylan-Kolchin of the University of California, Irvine performed a simulation of how giant galaxies such as the Milky Way grow by swallowing lesser galaxies, finding that dwarf galaxies moving as fast as Leo I are almost always bound to the giants, which means Leo I is a true satellite. Long story short, Boylan-Kolchin and team estimated that the Milky Way’s mass is of around 1.6 trillion suns or quite a bit larger than previously believed.

“The Milky Way is the keystone in understanding more distant galaxies,” Boylan-Kolchin says. “Therefore, getting a good mass for the Milky Way is very important for modeling the Milky Way and other galaxies.”

Findings were reported in the Astrophysical Journal

via Scientific American

The inset at left shows a close-up of the young dwarf galaxy. This image is a composite taken with Hubble's WFC 3 and ACS. Credit: NASA, ESA, and M. Postman and D. Coe (STScI) and CLASH Team.

Farthest known object in the Universe is 13.3 billion years old

The inset at left shows a close-up of the young dwarf galaxy. This image is a composite taken with Hubble's WFC 3 and ACS. Credit: NASA, ESA, and M. Postman and D. Coe (STScI) and CLASH Team.

The inset at left shows a close-up of the young dwarf galaxy. This image is a composite taken with Hubble’s WFC 3 and ACS. Credit: NASA, ESA, and M. Postman and D. Coe (STScI) and CLASH Team.

NASA scientists have announced they have discovered the farthest object discovered so far in the Universe, a 13.3 billion old galaxy or a mere 420 million years after the Big Bang.

That’s not to say that its 13.3 billion light years away from Earth, since the Universe has expanded greatly since then and the actual distance might be much greater than this figure. It means that light took 13.3 billion years to reach us.

The galaxy has been dubbed  MACS0647-JD and was discovered using a combination of NASA’s Hubble and Spitzer space telescopes, along with gravitational lensing – an interstellar technique that uses distant galaxies to create a zooming effect for the light that passes through them. Without gravitational lensing, this discovery would have been impossible with the current technology employed in telescopes.

“This [magnification galaxy] does what no manmade telescope can do,” Marc Postman, of Baltimore’s Space Telescope Institute, said in a release. “Without the magnification, it would require a Herculean effort to observe this galaxy.”

Essentially, the scientists have looked into the past – 13.3 billion years into the past. What they saw was a galaxy that was only a tiny fraction of the Milky Way. More exactly, it’s been estimated as being only 600 light years wide. For compassion, the Large Magellanic Cloud, a dwarf galaxy companion to the Milky Way, is 14,000 light-years wide. Our Milky Way is 150,000 light-years across.

Since then it has most likely grown, and even collided already with other galaxies. The previous record holder was a gamma ray burst just 600 million years after the Big Bang.

“Over the next 13 billion years, it may have dozens, hundreds, or even thousands of merging events with other galaxies and galaxy fragments,” Dan Coe, lead author of the study announcing the discovery, said in a release. “This object may be one of many building blocks of a galaxy.”

source: NASA

A high-resolution infrared image of the region surrounding the black hole at the center of our galaxy that shows the two orbits of the closest stars. Other orbits are shown in fainter orbits. (c) UCLA

Closest star orbiting our galaxy’s black hole discovered

Astronomers at UCLA university have made a remarkable discovery, after they’ve confirmed the presence of a star orbiting the black hole at the center of our galaxy in a mere 11-and-a-half years – that’s the shortest known orbit of any star near this black hole. The researchers involved in the paper describing the find claim that data will help test Einstein’s theory of relativity, which predicts space and time are warped around the gravitational field of a black hole.

A high-resolution infrared image of the region surrounding the black hole at the center of our galaxy that shows the two orbits of the closest stars. Other orbits are shown in fainter orbits. (c) UCLA

A high-resolution infrared image of the region surrounding the black hole at the center of our galaxy that shows the two orbits of the closest stars. Other orbits are shown in fainter orbits. (c) UCLA

The center of our galaxy is such a hectic place that direct and accurate optical observations around the black hole are simply impossible. Instead, scientists rely on the data they can gather by reading radio, X-ray and infrared waves. To their aid comes the Keck telescope on Mauna Kea in Hawaii, which has been watching stars near the galactic center in IR for 17 years, providing a detailed view of their dynamics. Using the telescope, astronomers answered some of the most puzzling astronomical questions in recent history, thus we now know:

  • at the center of our galaxy, lies a supermassive black hole some 26,000 light years ago, with a mass 4 million times that of our sun.
  • stars accelerate around the supermassive black hole. Further research should confirm the trend for the newly found, fastest orbiting star as well.
  • in 2005, the telescope took the first clear picture of the center of the Milky Way,  including the area surrounding the black hole, using laser guide star adaptive optics technology.

The newly confirmed star, dubbed SO-102, has had its orbit completely mapped, thanks to its short period. This is only the second star to have its orbit completely mapped, after the neighboring S0-2. Data from the two orbits together will help astronomers model the black hole itself, as direct IF observations are restricted due to it being invisible. Much of the merit for achieving these immense milestones in astronomy go to  Andrea Ghez, leader of the discovery team and a UCLA professor of physics and astronomy who holds the Lauren B. Leichtman and Arthur E. Levine Chair in Astrophysics. Ghez has  3,000 stars that orbit the black hole, and has been studying S0-2 since 1995.

“I’m extremely pleased to find two stars that orbit our galaxy’s supermassive black hole in much less than a human lifetime,” said Ghez.

“It is the tango of S0-102 and S0-2 that will reveal the true geometry of space and time near a black hole for the first time,” Ghez said. “This measurement cannot be done with one star alone.”

orbit animation

The first star with a sufficiently short orbital period to enable a complete three-dimensional reconstruction of its trajectory, SO-2, has an orbital period of around 16 years, but why did SO-102 take so long for it to be discovered? Well, the main reasons is that it’s very faint – around 16 times less brighter than SO-2. Thus, astronomers used the black hole data from prior observations to determine S0-102’s orbital properties, a feat made possible thanks to the Keck telescope’s novel adaptive optics technology, which allows for the 10-meter-diameter mirror to dynamically adjust in order to correct the distorting effects of the Earth’s atmosphere in real time.

“The Keck Observatory has been the leader in adaptive optics for more than a decade and has enabled us to achieve tremendous progress in correcting the distorting effects of the Earth’s atmosphere with high–angular resolution imaging,” Ghez said. “It’s really exciting to have access to the world’s largest and best telescope. It is why I came to UCLA and why I stay at UCLA.”

Milky Way’s dark core that warps time and space

Over time, Ghez and colleagues’ goals have evolved from demonstrating the existence of a black hole at the center of our galaxy, to validating fundamental laws of physics. At high velocities and gravity, Newtonian physics aren’t enough to explain irregularities in elliptical orbits, such as that of Mercury that has an irregular motion due to the sun’s mass to which it is in very close proximity. Measuring the warping effects of the Milky Way’s black hole on spacetime is a lot easier and evident than observations around the sun or similar stars, since the black hole is 4 million times more massive. Long term observations are required, however, in order to spot general relativistic effects, which are cumulative over multiple orbits.

One way for the scientists to test relativity is to measure the redshift, where the black hole’s gravitational influence stretches the wavelength of light towards the longer end of the electromagnetic spectrum.

“The fact that we can find stars that are so close to the black hole is phenomenal,” said Ghez, who also directs the UCLA Galactic Center Group. “Now it’s a whole new ballgame, in terms of the kinds of experiments we can do to understand how black holes grow over time, the role supermassive black holes play in the center of galaxies, and whether Einstein’s theory of general relativity is valid near a black hole, where this theory has never been tested before. It’s exciting to now have a means to open up this window.
“This should not be a neighborhood where stars feel particularly welcome,” she added. “But surprisingly, it seems that black holes are not as hostile to stars as was previously speculated.”

The findings were published in the journal Science.

source: UCLA newsroom

 

Artist's rendering of the oldest known spiral galaxy - 11 billion years old. The red area in the upper right corner is a dwarf galaxy that is merging with it. (Dunlap Institute for Astronomy & Astrophysics/Joe Bergeron)

Oldest spiral galaxy is a freak of cosmos

Artist's rendering of the oldest known spiral galaxy - 11 billion years old. The red area in the upper right corner is a dwarf galaxy that is merging with it. (Dunlap Institute for Astronomy & Astrophysics/Joe Bergeron)

Artist’s rendering of the oldest known spiral galaxy – 11 billion years old. The red area in the upper right corner is a dwarf galaxy that is merging with it. (Dunlap Institute for Astronomy & Astrophysics/Joe Bergeron)

In a remarkable discovery, astronomers have found the oldest spiral galaxy to our knowledge –  a three-armed spiral galaxy dating back nearly 11 billion years. It precedes any other previous record holder by about 2 billion years, basically sweeping away the competition. The spiral galaxy is so amazing that it caught astronomers completely by surprise, and even they couldn’t believe what they had stumbled upon at first.

“Our first thought was that we must have the wrong distance for the galaxy,” lead researcher David Law, with the University of Toronto, told Discovery News.

“Then we thought perhaps it was the human brain playing tricks on us. If you look at enough blobby, weird-looking galaxies sooner or later, like a Rorschach blob test, you start to pick out patterns whether or not they’re there,” Law said.

This wasn’t any illusion, any fabric of their imagination. Indeed, the spiral galaxy, dubbed Q2343-BX442 and located in the direction of the Pegasus constellation, had its structured imaged by the Hubble Space Telescope and was confirmed by the Keck II telescope in Hawaii, which studied the object’s internal motions. Studies of spectra from more than 3,600 locations in and around the galaxy revealed that it is, indeed, a rotating spiral galaxy.

The galaxy was present in the early universe, about 3 billion years after the Big Bang, at a time when galaxies were still forming and normally looked clumpy and irregular. “The vast majority of old galaxies look like train wrecks,” said UCLA astronomer Alice E. Shapley, one of the discoverers of the unusual spiral galaxy. “Our first thought was, why is this one so different, and so beautiful?”

Ancient galaxy has spiral days numbered

Ancient spiral galaxies are extremely rare. Actually out of a sample bundle of  306 Hubble Space Telescope imaged ancient galaxies, only ONE presented a spiral structure – the very object of discussion in this article, BX442. This very atypical placement of the spiral galaxy at such an early phase of the Universe is what sparked scientists to investigate it with great scrutiny. The team came to the conclusion that the galaxy’s shape is due to gravitational effects of a smaller galaxy in its vicinity. If that proves to be true, than BX442 wouldn’t had last as a spiral galaxy for too long.

Computer simulations show BX442, a relatively large galaxy with about the same mass as the Milky Way, would only last about 100 million years as a spiral structure.

“We think that we just happened to catch it at a very special time,” Shapley said. “I’d say by today, it probably doesn’t look like a spiral galaxy.”

Our own spiral galaxy, the Milky Way, belongs to a longer-lived class.

“One of the leading mechanisms that we believe explains modern day spirals, such as the Milky Way, is what is called ‘density wave theory,’ which doesn’t need any kind of nearby galaxy. It happens from the disk alone in isolation,” Law said.

The findings were reported in journal Nature.

Artist impression of a quasar. (c) NASA/ESA

Enormous water reservoir found in space is bigger than 140 trillion earth oceans

Astronomers have discovered the largest body of water so far known, a reservoir of water floating in space around a ancient distant quasar,  holding 140 trillion times the mass of water in the Earth’s oceans.

Artist impression of a quasar. (c) NASA/ESA

Artist impression of a quasar. (c) NASA/ESA

Remarkably enough, the find was dated as being 12 billion light years away, only  1.6 billion light years farther from the Big Bang.

“Since astronomers expected water vapor to be present even in the early universe, the discovery of water is not itself a surprise,” said the Carnegie Institution in statement, one of the groups behind the findings, said.

The water cloud was found to be in the central regions of a faraway quasar.

“Quasars contain massive black holes that steadily consuming a surrounding disk of gas and dust; as it eats, the quasar spews out amounts of energy,” the Institution continued in its statement.

And a lot of it, I might add. Quasars are the most powerful known entities in space, with this particular one pumping out 1,000 trillion times more energy than our sun, and 65,000 times the whole of the Milky Way. The black hole found at the quasar’s center has a mass 20 billion times greater than the sun.

NASA scientist Matt Bradford has said, “The environment around this quasar is very unique in that it’s producing this huge mass of water. It’s another demonstration that water is pervasive throughout the universe, even at the very earliest times.”

RELATED: Most distant quasar in the known Universe found

While water vapors are known to be found through out the Universe, it’s not that common of a sight. In the Milky Way, water vapor surfaces are found only in particular regions a few light years across at most, however, the water in the distant quasar appears to be spread over hundreds of light years.

The find came as part of a quasar study called “APM 08279+5255”, which gathered on observations first commenced by NASA three years ago in 2008, made using an instrument called “Z-Spec” at the California Institute of Technology’s Submillimeter Observatory. The instrument is a 33-foot (10-meter) telescope near the summit of Mauna Kea in Hawaii.

“Breakthroughs are coming fast in millimeter and submillimeter technology, enabling us to study ancient galaxies caught in the act of forming stars and supermassive black holes,” says CU-Boulder associate professor Jason Glenn.

Artist impression of a star getting ripped by a supermassive black hole. (c) Mark A. Garlick, University of Warwick

Intense Gamma Ray blast indeed traced back to supermassive black hole

Artist impression of a star getting ripped by a supermassive black hole. (c) Mark A. Garlick, University of Warwick

Artist impression of a star getting ripped by a supermassive black hole. (c) Mark A. Garlick, University of Warwick

We previously reported about an incredible gamma ray burst triggered by a black hole, so powerful that nothing like this was observed before, or even dimmed possible. A recently published paper in the journal Science sheds more light on the subject.

A typical gamma ray burst commonly occurs when massive stars explode due to collisions with other stars or simple from dying stars – these blasts of radiation usually last around 30 seconds, maybe a few minutes. This super Gamma Ray blast, first observed on 28th of March by the Swift telescope, went on it for days with high levels of radiation, and to this day it still hasn’t stop emitting. Actually, during its first couple of days of activity, the burst registered some wavelengths not visible to the naked eye as bright as a hundred billion suns, scientists report.

“This is probably the first time mankind has seen a phenomenon like this,” says astronomer Josh Bloom of the University of California- Berkeley, lead author of one of two studies on the outburst.

The study brings yet more evidence backing up the theory which say that the center of most big galaxies there’s a supermassive black hole, most of the time quite and dormant.

Swift and other satellites narrowed the origin of the March blast to the center of a galaxy about 22.4 billion trillion miles away or 3.8 billion light-years away, where a titanic black whole, weighing as much as 10 million times more than the sun, gobbled up a star and consumed its whole energy.

In addition, common gamma ray bursts are normally observed at the margin of a galaxy. Sw 1644+57, as the burst was dubbed, however was found in an unusual location – at the core of a galaxy.

“That’s the prime reason we started suspecting early on that a supermassive black hole was involved, because we know [galactic cores are] where these beasts reside.”

What’s remarkable is the game of chance which lead to the observation of this stunning phenomena. As the star was ripped apart by the black hole’s gravity, it was actually trained into a loop around the hole with the speed of light which caused a beam of radiation to spill out of latter’s center core. It took almost 4 billion years and precisely the perfect kind of geometry for the beam to hit Earth and astrophysicists to observe it.

“Seeing a star get ripped apart by a black hole from almost 4 billion light-years away, that’s a remarkable thing,” says astronomer Dave Goldberg, co-author of A User’s Guide to the Universe: Surviving the Perils of Black Holes, Time Paradoxes, and Quantum Uncertainty, who was not part of the studies. “We want to study black holes because they are tremendous natural laboratories for what happens to matter at very high energies.”

Dormant supermassive black holes are still a mystery for scientists, who still can’t unravel its spontaneous nature.

“What’s amazing,” Bloom said, “is that we have here an otherwise quiescent, starving black hole that has decided to go on a sudden feeding frenzy for a short period of time.”

Our galaxy, the Milky Way, seems to have a dormant supermassive black hole at its center as well, and if a Gamma Ray like the one presented earlier were to happen and point towards Earth, it would’ve wreak havoc. Chances something like this would ever happen, scientists assure, are astronomical.

APOD: fantastic time lapse of clouds and sky over the Canary Islands

Time lapse videos seem to be really in fashion as of late, but if directors keep editing videos like the one captioned right below you won’t ever see me complain. Featured in today’s Astronomy Picture of the Day by NASA, Daniel López time-lapsed flowing clouds, a setting sun that shows numerous green flashes, the Milky Way Galaxy rising, a colorful double fogbow, lenticular clouds that appear stationary near their mountain peaks, a mountain landscape towered by a colorful rainbow and some other hidden gems which I’ll leave for you to discoverer further.

The video was shot solely from the Teide National Park on Tenerife in the Canary Islands of Spain, off the north west coast of Africa. If you found this interesting, you should learn more about the various types of clouds.

Milky Way Has Mysterious Lopsided Cloud Of Antimatter: Clue To Origin Of Antimatter

dark matter
Antimatter is a fascinating story; basically nobody knows for sure what it could do and scientists have been trying to understand it for years. The artificial production of atoms of antimatter (specifically antihydrogen) first became a reality in the early 1990s. For example an atom of antihydrogen is composed of a negatively-charged antiproton being orbited by a positively-charged positron. But still the clue that our old Milky Way galaxy gave us is relevant and important.

The thing is that the proton traveling at relativistic speeds and passing close to the nucleus of an atom has the potential to force the creation of an electron-positron pair. The shape of the mysterious cloud of antimatter in the central regions of the Milky Way has been revealed by ESA’s orbiting gamma-ray observatory Integral.

These observations almost eliminated the idea that the chances that the antimatter is coming from the annihilation or decay of astronomical dark matter. Georg Weidenspointner at the Max Planck Institute for Extraterrestrial Physics and an international team of astronomers made the discovery using four-years-worth of data from Integral.

“Simple estimates suggest that about half and possibly all of the antimatter is coming from the X-ray binaries,” says Weidenspointner. The other half could be coming from a similar process around the galaxy’s central black hole and the various exploding stars there. He points out that the lopsided distribution of hard LMXBs is unexpected, as stars are distributed more or less evenly around the galaxy. More investigations are needed to determine whether the observed distribution is real.