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Posts Tagged ‘galaxies’

An Unprecedented View Of Two Hundred Galaxies Of The Local Universe

October 2, 2014 Leave a comment

Galaxies are the result of an evolutionary process started thousands of million years ago, and their history is coded in their distinct components. The CALIFA project is intended to decode the galaxies’ history in a sort of galactic archaeology, through the 3D observations of a sample of six hundred galaxies. With this second data release corresponding to two hundred galaxies, the project reaches its halfway point with important results behind.

The CALIFA Project allows not only to inspect the galaxies in detail, but it also provides with data on the evolution of each particular galaxy with time: how much gas and when was it converted into stars along each phase of the galaxy’s life, and how did each region of the galaxies evolve along the more than ten thousand million years of cosmic evolution.

Thanks to the CALIFA data, the astronomers have been able to deduce the history of the mass, luminosity and chemical evolution of the CALIFA sample of galaxies, and thus they have found that more massive galaxies grow faster than less massive ones, and that they form their central regions before the external ones (inside-out mass assembly).

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Hawaii Scientist Maps, Names Laniakea, Our Home Supercluster Of Galaxies

September 3, 2014 Leave a comment

University of Hawaii at Manoa astronomer R. Brent Tully, who recently shared the 2014 Gruber Cosmology Prize and the 2014 Victor Ambartsumian International Prize, has led an international team of astronomers in defining the contours of the immense supercluster of galaxies containing our own Milky Way. They have named the supercluster “Laniakea,” meaning “immense heaven” in Hawaiian. The paper explaining this work is the cover story of the September 4 issue of the prestigious journal Nature.

Galaxies are not distributed randomly throughout the universe. Instead, they are found in groups, like our own Local Group, that contain dozens of galaxies, and in massive clusters containing hundreds of galaxies, all interconnected in a web of filaments in which galaxies are strung like pearls. Where these filaments intersect, we find huge structures, called “superclusters.” These structures are interconnected, but they have poorly defined boundaries.

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Mapping Dark Matter, 4.5 Billion light Years Away


Credit: ESA/Hubble, NASA, HST Frontier Fields

Credit: ESA/Hubble, NASA, HST Frontier Fields

Using the NASA/ESA Hubble Space Telescope, an international team of astronomers have mapped the mass within a galaxy cluster more precisely than ever before. Created using observations from Hubble’s Frontier Fields observing programme, the map shows the amount and distribution of mass within MCS J0416.1–2403, a massive galaxy cluster found to be 160 trillion times the mass of the Sun.

The detail in this ‘mass map’ was made possible thanks to the unprecedented depth of data provided by new Hubble observations, and the cosmic phenomenon known as strong gravitational lensing. The team, led by Dr Mathilde Jauzac of Durham University in the UK and the Astrophysics & Cosmology Research Unit in South Africa, publish their results in the journal Monthly Notices of the Royal Astronomical Society.

Measuring the amount and distribution of mass within distant objects in the Universe can be very difficult. A trick often used by astronomers is to explore the contents of large clusters of galaxies by studying the gravitational effects they have on the light from very distant objects beyond them. This is one of the main goals of Hubble’s Frontier Fields, an ambitious observing programme scanning six different galaxy clusters — including MCS J0416.1–2403.

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Hubble Shows Farthest Lensing Galaxy Yields Clues To Early Universe


Credit: NASA, ESA, K.-V. Tran (Texas A&M University), and K. Wong (Academia Sinica Institute of Astronomy & Astrophysics)

Credit: NASA, ESA, K.-V. Tran (Texas A&M University), and K. Wong (Academia Sinica Institute of Astronomy & Astrophysics)

Astronomers using NASA’s Hubble Space Telescope have unexpectedly discovered the most distant cosmic magnifying glass, produced by a monster elliptical galaxy. Seen here as it looked 9.6 billion years ago, this monster elliptical galaxy breaks the previous record holder by 200 million years. These “lensing” galaxies are so massive that their gravity bends, magnifies, and distorts light from objects behind them, a phenomenon called gravitational lensing.

The object behind the cosmic lens is a tiny spiral galaxy undergoing a rapid burst of star formation. Its light has taken 10.7 billion years to arrive here. Seeing this chance alignment at such a great distance from Earth is a rare find.

Locating more of these distant lensing galaxies will offer insight into how young galaxies in the early universe built themselves up into the massive dark-matter-dominated galaxies of today. Dark matter cannot be seen, but it accounts for the bulk of the universe’s matter.

“When you look more than 9 billion years ago in the early universe, you don’t expect to find this type of galaxy-galaxy lensing at all,” explained lead researcher Kim-Vy Tran of Texas A&M University in College Station. “It’s very difficult to see an alignment between two galaxies in the early universe.”

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Australian Researchers Pioneer A ‘Google Street View’ Of Galaxies


A new home-grown instrument based on bundles of optical fibres is giving Australian astronomers the first ‘Google street view’ of the cosmos — incredibly detailed views of huge numbers of galaxies.

Developed by researchers at the University of Sydney and the Australian Astronomical Observatory, the optical-fibre bundles can sample the light from up to 60 parts of a galaxy, for a dozen galaxies at a time.

By analysing the light’s spectrum astronomers can learn how gas and stars move within each galaxy, where the young stars are forming and where the old stars live. This will allow them to better understand how galaxies change over time and what drives that change.

“It’s a giant step,” said Dr James Allen of the ARC Centre of Excellence for All-sky Astrophysics(CAASTRO) at the University of Sydney.

“Before, we could study one galaxy at a time in detail, or lots of galaxies at once but in much less detail. Now we have both the numbers and the detail.”

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Hubble Traces The Halo Of A Galaxy More Accurately Than Ever Before


Image credit: ESA/Hubble, NASA, Digitized Sky Survey, MPG/ESO

Image credit: ESA/Hubble, NASA, Digitized Sky Survey, MPG/ESO

Astronomers using the NASA/ESA Hubble Space Telescope have probed the extreme outskirts of the stunning elliptical galaxy Centaurus A. The galaxy’s halo of stars has been found to extend much further from the galaxy’s centre than expected and the stars within this halo seem to be surprisingly rich in heavy elements. This is the most remote portion of an elliptical galaxy ever to have been explored.

There is more to a galaxy than first meets the eye. Extending far beyond the bright glow of a galaxy’s centre, the swirling spiral arms, or the elliptical fuzz, is an extra component: a dim halo of stars sprawling into space.

These expansive haloes are important components of a galaxy. The halo of our own galaxy, the Milky Way, preserves signatures of both its formation and evolution. Yet, we know very little about the haloes of galaxies beyond our own as their faint and spread-out nature makes exploring them more difficult. Astronomers have so far managed to detect very few starry haloes around other galaxies.

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Silhouettes Of Early Galaxies Reveal Few Seeds For New Stars


An international team of astronomers has discovered that gas around young galaxies is almost barren, devoid of the seeds from which new stars are thought to form—molecules of hydrogen.

Without starlight to see them directly, the team, which includes Dr. Regina Jorgenson of the Institute for Astronomy at the University of Hawaii at Manoa—observed the young galaxies’ outskirts in silhouette.

They searched for telltale signs of hydrogen molecules absorbing the light from background objects called quasars—supermassive black holes sucking in surrounding material—that glow very brightly.

“Previous experiments led us to expect molecules in about 10 of the 90 young galaxies we observed, but we found just one case,” said Associate Professor Michael Murphy from Swinburne University of Technology in Australia. He co-led the study with Jorgenson.

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Small, But Plentiful: How The Faintest Galaxies Illuminated The Early Universe


Astronomers investigating behaviour of the universe shortly after the Big Bang have made a surprising discovery: the properties of the early universe are determined by the smallest galaxies. The team report their findings in a paper published today in the journal Monthly Notices of the Royal Astronomical Society.

Shortly after the Big Bang, the universe was ionised: ordinary matter consisted of hydrogen with its positively charged protons stripped of their negatively charged electrons. Eventually, the universe cooled enough for electrons and protons to combine and form neutral hydrogen. This cool gas will eventually form the first stars in the universe but for millions of years, there are no stars. Astronomers therefore aren’t able to see how the cosmos evolved during these ‘dark ages’ using conventional telescopes. The light returned when newly forming stars and galaxies re-ionised the universe during the ‘epoch of re-ionisation’.

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E-ELT (European Extremely Large Telescope)


The E-ELT (European Extremely Large Telescope) project aims to provide European astronomers with the largest optical-infrared telescope in the world. With a diameter of 40m and incorporating a large deformable mirror, the E-ELT is expected to tackle the biggest scientific challenges of our time, and aim for a number of notable firsts, including tracking down Earth-like planets around other stars in the “habitable zones” where life could exist. It will also perform “stellar archaeology” in nearby galaxies, as well as make fundamental contributions to cosmology by measuring the properties of the first stars and galaxies and probing the nature of dark matter and dark energy.

The telescope will gather 15 times more light than the largest optical telescopes operating today. The telescope has an innovative five-mirror design that includes advanced adaptive optics to correct for the turbulent atmosphere, giving exceptional image quality. The main mirror will be made up from almost 1000 hexagonal segments.

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A Turbulent Birth for Stars In Merging Galaxies


Using state of the art computer simulations, a team of French astrophysicists have for the first time explained a long standing mystery: why surges of star formation (so called ‘starbursts’) take place when galaxies collide. The scientists, led by Florent Renaud of the AIM institute near Paris in France, publish their results in a letter to the journal Monthly Notices of the Royal Astronomical Society.

Stars form when the gas inside galaxies becomes dense enough to collapse, usually under the effect of gravitation. When galaxies merge however, this increases the random motions of their gas generating whirls of turbulence which should hinder the collapse of the gas. Intuitively this turbulence should then slow down or even shut down the formation of stars, but in reality astronomers observe the opposite.

The new simulations were made using two of the most powerful supercomputers in Europe. The team modelled a galaxy like our own Milky Way and the two colliding Antennae galaxies.

For the Milky Way type galaxy, the astrophysicists used 12 million hours of time on the supercomputer Curie, running over a period of 12 months to simulate conditions across 300,000 light years. For the Antennae type system, the scientists used the supercomputer SuperMUC to cover 600,000 light years. This time they needed 8 million hours of computational time over a period of 8 months. With these enormous computing resources the team were able to model the systems in great detail, investigating details that were only a fraction of a light year across.

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