Laniakea supercluster: Newly identified galactic supercluster, home to the Milky Way

A slice of the Laniakea Supercluster in the supergalactic equatorial plane, an imaginary plane containing many of the most massive clusters in this structure. 

The colours represent density within this slice, with red for high densities and blue for voids, areas with relatively little matter. 

Individual galaxies are shown as white dots. 

Velocity flow streams within the region gravitationally dominated by Laniakea are shown in white, while dark blue flow lines are away from the Laniakea local basin of attraction. 

The orange contour encloses the outer limits of these streams, a diameter of about 160 Mpc. This region contains the mass of about 100 million billion suns. 

Credit: SDvision interactive visualization software by DP at CEA/Saclay, France.

Astronomers using the National Science Foundation's Green Bank Telescope (GBT), among other telescopes, have determined that our own Milky Way galaxy is part of a newly identified ginormous supercluster of galaxies, which they have dubbed "Laniakea," which means "immense heaven" in Hawaiian.

This discovery clarifies the boundaries of our galactic neighbourhood and establishes previously unrecognized linkages among various galaxy clusters in the local Universe.

"We have finally established the contours that define the supercluster of galaxies we can call home," said lead researcher R. Brent Tully, an astronomer at the University of Hawaii at Manoa.

"This is not unlike finding out for the first time that your hometown is actually part of much larger country that borders other nations."

The paper explaining this work is the cover story of the September 4 issue of the journal Nature.

Superclusters are among the largest structures in the known Universe. They are made up of groups, like our own Local Group, that contain dozens of galaxies, and massive clusters that contain hundreds of galaxies, all interconnected in a web of filaments.

Though these structures are interconnected, they have poorly defined boundaries.

To better refine cosmic mapmaking, the researchers are proposing a new way to evaluate these large-scale galaxy structures by examining their impact on the motions of galaxies.

A galaxy between structures will be caught in a gravitational tug-of-war in which the balance of the gravitational forces from the surrounding large-scale structures determines the galaxy's motion.

By using the GBT and other radio telescopes to map the velocities of galaxies throughout our local Universe, the team was able to define the region of space where each supercluster dominates.

"Green Bank Telescope observations have played a significant role in the research leading to this new understanding of the limits and relationships among a number of superclusters," said Tully.


The Milky Way resides in the outskirts of one such supercluster, whose extent has for the first time been carefully mapped using these new techniques.

This so-called Laniakea Supercluster is 500 million light-years in diameter and contains the mass of one hundred million billion Suns spread across 100,000 galaxies.

This study also clarifies the role of the Great Attractor, a gravitational focal point in intergalactic space that influences the motion of our Local Group of galaxies and other galaxy clusters.

Two views of the Laniakea Supercluster. 

Credit: SDvision interactive visualization software by DP at CEA/Saclay, France

Within the boundaries of the Laniakea Supercluster, galaxy motions are directed inward, in the same way that water streams follow descending paths toward a valley.

The Great Attractor region is a large flat bottom gravitational valley with a sphere of attraction that extends across the Laniakea Supercluster.

The name Laniakea was suggested by Nawa'a Napoleon, an associate professor of Hawaiian Language and chair of the Department of Languages, Linguistics, and Literature at Kapiolani Community College, a part of the University of Hawaii system. The name honors Polynesian navigators who used knowledge of the heavens to voyage across the immensity of the Pacific Ocean.

More information: Nature, dx.doi.org/10.1038/nature13674

N103B Supernova explosion: New suspect identified

This infrared image from NASA's Spitzer Space Telescope shows N103B, all that remains from a supernova that exploded a millennium ago in the Large Magellanic Cloud, a satellite galaxy 160,000 light-years away from our own Milky Way. 

Credit: NASA/JPL-Caltech/Goddard

Supernovas are often thought of as the tremendous explosions that mark the ends of massive stars' lives.

While this is true, not all supernovas occur in this fashion.

A common supernova class, called Type Ia, involves the detonation of white dwarfs, small, dense stars that are already dead.

New results from NASA's Spitzer Space Telescope have revealed a rare example of Type Ia explosion, in which a dead star "fed" off an aging star like a cosmic zombie, triggering a blast.

The results help researchers piece together how these powerful and diverse events occur.

"It's kind of like being a detective," said Brian Williams of NASA's Goddard Space Flight Center in Greenbelt, Maryland, lead author of a study submitted to the Astrophysical Journal.

"We look for clues in the remains to try to figure out what happened, even though we weren't there to see it."

Supernovas are essential factories in the cosmos, churning out heavy metals, including the iron contained in our blood.

Type Ia supernovas tend to blow up in consistent ways, and thus have been used for decades to help scientists study the size and expansion of our universe.

Researchers say that these events occur when white dwarfs, the burnt-out corpses of stars like our sun, explode.

Evidence has been mounting over the past 10 years that the explosions are triggered when two orbiting white dwarfs collide, with one notable exception.

Kepler's supernova, named after the astronomer Johannes Kepler, who was among those who witnessed it in 1604, is thought to have been preceded by just one white dwarf and an elderly, companion star called a red giant.

Scientists know this because the remnant sits in a pool of gas and dust shed by the aging star.

Spitzer's new observations now find a second case of a supernova remnant resembling Kepler's.

Called N103B, the roughly 1,000 year-old supernova remnant lies 160,000 light-years away in the Large Magellanic Cloud, a small galaxy near our Milky Way.

"It's like Kepler's older cousin," said Williams. He explained that N103B, though somewhat older than Kepler's supernova remnant, also lies in a cloud of gas and dust thought to have been blown off by an older companion star. "The region around the remnant is extraordinarily dense," he said.

Unlike Kepler's supernova remnant, no historical sightings of the explosion that created N103B are recorded.

Both the Kepler and N103B explosions are thought to have unfolded as follows: an aging star orbits its companion, a white dwarf.

As the aging star molts, which is typical for older stars, some of the shed material falls onto the white dwarf. This causes the white dwarf to build up in mass, become unstable and explode.

According to the researchers, this scenario may be rare. While the pairing of white dwarfs and red giants was thought to underlie virtually all Type Ia supernovas as recently as a decade ago, scientists now think that collisions between two white dwarfs are the most common cause.

The new Spitzer research highlights the complexity of these tremendous explosions and the variety of their triggers. The case of what makes a dead star rupture is still very much an unsolved mystery.

ESA VLT: Oldest solar twin identified

This image tracks the life of a Sun-like star, from its birth on the left side of the frame to its evolution into a red giant star on the right. 

On the left the star is seen as a protostar, embedded within a dusty disc of material as it forms. It later becomes a star like our Sun. 

After spending the majority of its life in this stage, the star's core begins to gradually heat up, the star expands and becomes redder until it transforms into a red giant. 

Following this stage, the star will push its outer layers into the surrounding space to form an object known as a planetary nebula, while the core of the star itself will cool into a small, dense remnant called a white dwarf star. 

Marked on the lower timeline are where our Sun and solar twins 18 Sco and HIP 102152 are in this life cycle. 

The Sun is 4.6 billion years old and 18 Sco is 2.9 billion years old, while the oldest solar twin is some 8.2 billion years old -- the oldest solar twin ever identified. 

By studying HIP 102152, we can get a glimpse of what the future holds for our Sun. 

This image is illustrative; the ages, sizes, and colours are approximate (not to scale). The protostar stage, on the far left of this image, can be some 2000 times larger than our Sun. 

The red giant stage, on the far right of this image, can be some 100 times larger than the Sun. 

Credit: ESO/M. Kornmesser

An international team led by astronomers in Brazil has used ESO's Very Large Telescope to identify and study the oldest solar twin known to date.

Located 250 light-years from Earth, the star HIP 102152 is more like the Sun than any other solar twin—except that it is nearly four billion years older.

This older, but almost identical, twin gives us an unprecedented chance to see how the Sun will look when it ages.

The new observations also provide an important first clear link between a star's age and its lithium content, and in addition suggest that HIP 102152 may be host to rocky terrestrial planets.

Astronomers have only been observing the Sun with telescopes for 400 years—a tiny fraction of the Sun's age of 4.6 billion years.

It is very hard to study the history and future evolution of our star, but we can do this by hunting for rare stars that are almost exactly like our own, but at different stages of their lives.

Now astronomers have identified a star that is essentially an identical twin to our Sun, but 4 billion years older—almost like seeing a real version of the twin paradox in action.

Jorge Melendez (Universidade de São Paulo, Brazil), the leader of the team and co-author of the new paper explains: "For decades, astronomers have been searching for solar twins in order to know our own life-giving Sun better.

But very few have been found since the first one was discovered in 1997. We have now obtained superb-quality spectra from the VLT and can scrutinise solar twins with extreme precision, to answer the question of whether the Sun is special."

The team studied two solar twins—one that was thought to be younger than the Sun (18 Scorpii) and one that was expected to be older (HIP 102152).

They used the UVES spectrograph on the Very Large Telescope (VLT) at ESO's Paranal Observatory to split up the light into its component colours so that the chemical composition and other properties of these stars could be studied in great detail.

They found that HIP 102152 in the constellation of Capricornus (The Sea Goat) is the oldest solar twin known to date.

It is estimated to be 8.2 billion years old, compared to 4.6 billion years for our own Sun. On the other hand 18 Scorpii was confirmed to be younger than the Sun—about 2.9 billion years old.

More information: This research was presented in a paper to appear in "High precision abundances of the old solar twin HIP 102152: insights on Li depletion from the oldest Sun", by TalaWanda Monroe et al. in the Astrophysical Journal Letters. Research paper PDF

Bizarre real time face-substitution system demonstrated

Faces from arturo castro on Vimeo.

Some day in the not-too-distant future, you may be on a service like Chatroulette, and suddenly find yourself matched up with a person who looks exactly like Angelina Jolie.

Well, chances are it won't really be her. Instead, it will likely be someone using the descendant of a system put together by Arturo Castro. Using a combination of existing software, the Barcelona digital artist has demonstrated how a variety of famous faces can be mapped onto his own, moving with it in real time.

While Castro's system isn't likely to fool anyone - in its present version - it's an unsettling indication of what could be possible with just a little more finessing.

Castro's application was created using openFrameworks, an open source framework for creative coding. This was combined with FaceTracker, which produces a virtual mesh that matches a human subject's facial features.

The colours of the famous faces were blended with those of Arturo's own using an image clone code developed by artist Kevin Atkinson. Finally, the FaceTracker meshes were wrapped around his face using the ofxFaceTracker add-on for openFrameworks.

The resulting video, which can be seen below, alternates between being funny and just plain creepy, with Castro taking on the identities of celebrities such as Marilyn Monroe, Michael Jackson and Paris Hilton.

Face Substitution from Kyle McDonald on Vimeo.

Potentially hazardous asteroid identified - It will collide with the Earth in 2182

“The total impact probability of asteroid ‘(101955) 1999 RQ36′ can be estimated in 0.00092 — approximately one-in-a-thousand chance-, but what is most surprising is that over half of this chance (0.00054) corresponds to 2182,” explains to SINC María Eugenia Sansaturio, co-author of the study and researcher of Universidad de Valladolid (UVA).

The research also involved scientists from the University of Pisa (Italy), the Jet Propulsion Laboratory (USA) and INAF-IASF-Rome (Italy).

Scientists have estimated and monitored the potential impacts for this asteroid through 2200 by means of two mathematical models (Monte Carlo Method and line of variations sampling). Thus, the so called Virtual Impactors (VIs) have been searched.

VIs are sets of statistical uncertainty leading to collisions with the Earth on different dates of the XXII century. Two VIs appear in 2182 with more than half the chance of impact.

Asteroid ‘(101955) 1999 RQ36′ is part of the Potentially Hazardous Asteroids (PHA), which have the possibility of hitting the Earth due to the closeness of their orbits, and they may cause damages. This PHA was discovered in 1999 and has around 560 meters in diameter.

The Yarkovsky effect
In practice, its orbit is well determined thanks to 290 optical observations and 13 radar measurements, but there is a significant “orbital uncertainty” because, besides gravity, its path is influenced by the Yarkovsky effect.

Such disturbance slightly modifies the orbits of the Solar System’s small objects because, when rotating, they radiate from one side the radiation they take from the sun through the other side.

The research, which has been published in Icarus journal, predicts what could happen in the upcoming years considering this effect.

• Up to 2060, divergence of the impacting orbits is moderate;
  
• between 2060 and 2080 it increases 4 orders of magnitude because the asteroid will approach the Earth in those years;
  
• then, it increases again on a slight basis until another approach in 2162, it then decreases,
  
• 2182 is the most likely year for the collision.

“The consequence of this complex dynamic is not just the likelihood of a comparatively large impact, but also that a realistic deflection procedure (path deviation) could only be made before the impact in 2080, and more easily, before 2060,” stands out Sansaturio.

The scientist concludes: “If this object had been discovered after 2080, the deflection would require a technology that is not currently available.

Therefore, this example suggests that impact monitoring, which up to date does not cover more than 80 or 100 years, may need to encompass more than one century.

Thus, the efforts to deviate this type of objects could be conducted with moderate resources, from a technological and financial point of view.”

Illegal toxic waste spotted from space - environment - New Scientist

Illegal toxic waste spotted from space - environment - New Scientist

MOVE over Erin Brockovich. Today's environmental detectives can use radar, helicopters and even satellite images to help them spot illegal toxic waste dumps and help catch those responsible.

Ironically, the tightening of restrictions on waste disposal and the enforcement of new recycling laws have made illegal dumping more likely, turning it into big business for the criminals involved.

The trouble is digging up suspect dumps to investigate their contents can release toxins into local water supplies. But with new remote-sensing techniques, such as ground-penetrating radar (GPR), you can find toxic trash without disturbing the soil. Instead, you bounce microwaves off buried materials and the strength of returning signals provides clues to what they are.

Alastair Ruffell, a forensic geologist at Queen's University, Belfast in the UK, has used GPR in 17 cases for the environment agencies of Scotland, the Republic of Ireland and Northern Ireland. Most are ongoing, however three have resulted in the culprits being jailed and fined.

Ruffell's latest research shows that geophysical techniques can be used to characterise the waste (Environmental Forensics, DOI: 10.1080/15275920903130230). GPR surveys suggested the presence of a highly conductive waste such as farmyard slurry in a peat bog in Northern Ireland, simply because the suspect pocket in the bog reflected no microwaves.

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