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Archive for the ‘Galaxies’ Category

We’ve Revealed A Galaxy Far, Far Away….


BETA_snap_smThe galaxy was uncovered in radio emission travelling to Earth using CSIRO’s Australian SKA Pathfinder telescope (ASKAP), located at the Murchison Radio-astronomy Observatory (MRO).

The team used a special technique to detect a change in radio waves coming from within the bright centre of the galaxy PKS B1740-517, located near the Ara constellation.

The five-billion-year-old radio emission was stamped with the ‘imprint’ of hydrogen gas it had travelled through on its way to Earth.

The gas absorbs some of the emission, creating a tiny dip in the signal. “At many observatories, this dip would have been hidden by background radio noise, but our site is so radio quiet it stood out clearly,” Dr Allison said.

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Astronomers ‘Unscramble’ Einstein Ring To Reveal Most Detailed View Ever Of Star Formation In The Distant Universe


Credit: ALMA (NRAO/ESO/NAOJ)/Y. Tamura (The University of Tokyo)/Mark Swinbank (Durham University)

Credit: ALMA (NRAO/ESO/NAOJ)/Y. Tamura (The University of Tokyo)/Mark Swinbank (Durham University)

ALMA’s Long Baseline Campaign produced spectacular images of the distant, gravitationally lensed galaxy called HATLAS J090311.6+003906, otherwise known as SDP.81. New analyses of these images reveal details never before seen in a galaxy so remote, including phenomenally massive yet concentrated clumps of star-forming material.

The ALMA observations of SDP.81, made at the end of 2014, were enabled by a cosmic effect known as gravitational lensing. A large galaxy nestled between SDP.81 and ALMA is acting as a lens, magnifying the more distant galaxy’s light and warping it into a near-perfect example of a phenomenon known as an Einstein Ring.

In the months following these observations, at least seven groups of scientists have independently analyzed the ALMA data on SDP.81. This flurry of research papers has divulged unprecedented information about the galaxy, including details about its structure, contents, motion, and other physical characteristics.

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Nearby “Dwarf” Galaxy Is Home To Luminous Star Cluster


The NGC 5253 galaxy as seen through the Hubble Space Telescope

The NGC 5253 galaxy as seen through the Hubble Space Telescope

A team of Tel Aviv University and UCLA astronomers have discovered a remarkable cluster of more than a million young stars are forming in a hot, dusty cloud of molecular gases in a tiny galaxy very near our own.

The star cluster is buried within a massive gas cloud dubbed “Cloud D” in the NGC 5253 dwarf galaxy, and, although it’s a billion times brighter than our sun, is barely visible, hidden by its own hot gases and dust. The star cluster contains more than 7,000 massive “O” stars: the most brilliant stars extant, each a million times more luminous than our sun.

“Cloud D is an incredibly efficient star and soot factory,” says Prof. Sara Beck of TAU’s Department of Astronomy and Astrophysics and co-author of the research, recently published in Nature. “This cloud has created a huge cluster of stars, and the stars have created an unprecedented amount of dust.”

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Exiled Stars Explode Far From Home


Artist's concept. Image by Dr. Alex H Parker, NASA and the SDSS

Artist’s concept. Image by Dr. Alex H Parker, NASA and the SDSS

Sharp images obtained by the Hubble Space Telescope confirm that three supernovae discovered several years ago exploded in the dark emptiness of intergalactic space, having been flung from their home galaxies millions or billions of years earlier.

Most supernovae are found inside galaxies containing hundreds of billions of stars, one of which might explode per century per galaxy.

These lonely supernovae, however, were found between galaxies in three large clusters of several thousand galaxies each. The stars’ nearest neighbors were probably 300 light years away, nearly 100 times farther than our sun’s nearest stellar neighbor, Proxima Centauri, 4.24 light years distant.

uch rare solitary supernovae provide an important clue to what exists in the vast empty spaces between galaxies, and can help astronomers understand how galaxy clusters formed and evolved throughout the history of the universe.

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NASA’s WISE Spacecraft Discovers Most Luminous Galaxy In Universe

May 21, 2015 1 comment

Artist's concept. Image credit: N/A

Artist’s concept. Image credit: N/A

A remote galaxy shining with the light of more than 300 trillion suns has been discovered using data from NASA’s Wide-field Infrared Survey Explorer (WISE). The galaxy is the most luminous galaxy found to date and belongs to a new class of objects recently discovered by WISE — extremely luminous infrared galaxies, or ELIRGs.

“We are looking at a very intense phase of galaxy evolution,” said Chao-Wei Tsai of NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, lead author of a new report appearing in the May 22 issue of The Astrophysical Journal. “This dazzling light may be from the main growth spurt of the galaxy’s black hole.

The brilliant galaxy, known as WISE J224607.57-052635.0, may have a behemoth black hole at its belly, gorging itself on gas. Supermassive black holes draw gas and matter into a disk around them, heating the disk to roaring temperatures of millions of degrees and blasting out high-energy, visible, ultraviolet, and X-ray light. The light is blocked by surrounding cocoons of dust. As the dust heats up, it radiates infrared light.

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Galaxy’s Snacking Habits Revealed


Images Credit: Angel Lopez-Sanchez (AAO/MQU) and Baerbel Koribalski (CSIRO)

Images Credit: Angel Lopez-Sanchez (AAO/MQU) and Baerbel Koribalski (CSIRO)

A team of Australian and Spanish astronomers have caught a greedy galaxy gobbling on its neighbours and leaving crumbs of evidence about its dietary past.

Galaxies grow by churning loose gas from their surroundings into new stars, or by swallowing neighbouring galaxies whole. However, they normally leave very few traces of their cannibalistic habits.

A study published today in Monthly Notices of the Royal Astronomical Society (MNRAS) not only reveals a spiral galaxy devouring a nearby compact dwarf galaxy, but shows evidence of its past galactic snacks in unprecedented detail.

Australian Astronomical Observatory (AAO) and Macquarie University astrophysicist, Ángel R. López-Sánchez, and his collaborators have been studying the galaxy NGC 1512 to see if its chemical story matches its physical appearance.

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Discovery Of An Extremely Young Stellar Clump In The Distant Universe


Credits: CEA/HST

Credits: CEA/HST

As part of an observing program carried out with the Subaru Telescope and the Hubble Space Telescope, a group of researchers from the “Service d’Astrophysique-Laboratoire AIM” of CEA-IRFU led by Anita Zanella discovered the birth cry of a massive star-forming clump in the disk of a very distant galaxy. This giant clump is less than 10 million years old, and it is the very first time that such a young star-forming region is observed in the distant Universe. This discovery sheds new light on how stars were born within distant galaxies. The physical properties of this object reveal that newly-born clumps in such galaxies survive from stellar winds and supernovae feedback, and can thus live for a few hundred million years unlike the predictions from several theoretical models. Their long lifetime could enable their migration toward the inner regions of the galaxy, hence contributing to the total mass of the galactic bulge and the growth of the central black hole. These results are published in the “Nature” journal from May 2015.

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Scientists At Keck Discover The Fluffiest Galaxies


Credit: P. van Dokkum, R. Abraham, J. Brodie

Credit: P. van Dokkum, R. Abraham, J. Brodie

An international team of researchers led by Pieter van Dokkum at Yale University have used the W. M. Keck Observatory to confirm the existence of the most diffuse class of galaxies known in the universe. These “fluffiest galaxies” are nearly as wide as our own Milky Way galaxy – about 60,000 light years – yet harbor only one percent as many stars. The findings were recently published in the Astrophysical Journal Letters.

“If the Milky Way is a sea of stars, then these newly discovered galaxies are like wisps of clouds”, said van Dokkum. “We are beginning to form some ideas about how they were born and it’s remarkable they have survived at all. They are found in a dense, violent region of space filled with dark matter and galaxies whizzing around, so we think they must be cloaked in their own invisible dark matter ‘shields’ that are protecting them from this intergalactic assault.”

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Cause Of Galactic Death: Strangulation


Artist’s impression. Credit: re-active

Artist’s impression. Credit: re-active

As murder mysteries go, it’s a big one: how do galaxies die and what kills them? A new study, published today in the journal Nature, has found that the primary cause of galactic death is strangulation, which occurs after galaxies are cut off from the raw materials needed to make new stars.

Researchers from the University of Cambridge and the Royal Observatory Edinburgh have found that levels of metals contained in dead galaxies provide key ‘fingerprints’, making it possible to determine the cause of death.

There are two types of galaxies in the Universe: roughly half are ‘alive’ galaxies which produce stars, and the other half are ‘dead’ ones which don’t. Alive galaxies such as our own Milky Way are rich in the cold gas – mostly hydrogen – needed to produce new stars, while dead galaxies have very low supplies. What had been unknown is what’s responsible for killing the dead ones.

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Hubble Finds Massive Halo Around The Andromeda Galaxy


University of Notre Dame astrophysicist Nicolas Lehner has led a team of scientists who have used NASA’s Hubble Space Telescope to identify an immense halo of gas surrounding the Andromeda Galaxy, the nearest major galaxy to Earth. The halo stretches about a million light-years from Andromeda, halfway to the Milky Way. The discovery will tell astronomers more about the evolution and structure of giant spiral galaxies such as the Milky Way and Andromeda.

“Halos are the gaseous atmospheres of galaxies,” said Lehner, the lead investigator. “The properties of these gaseous halos control the rate at which stars form in galaxies.” The gargantuan halo is estimated to contain at least as much mass in its diffuse gas as half of the stars in the Andromeda Galaxy.

The Andromeda Galaxy, also known as Messier 31 or M31, is the most massive galaxy in the Local Group of galaxies that also includes the Milky Way and about 45 other known galaxies. M31 contains one trillion stars, about double the number of stars in the Milky Way. It is estimated to be about 25 percent more luminous than the Milky Way and lies 2.5 million light-years away.

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