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Posts Tagged ‘Milky Way’

Dark Matter Half What We Thought, Say Scientists

October 9, 2014 Leave a comment

A new measurement of dark matter in the Milky Way has revealed there is half as much of the mysterious substance as previously thought.

Australian astronomers used a method developed almost 100 years ago to discover that the weight of dark matter in our own galaxy is 800 000 000 000 (or 8 x 1011) times the mass of the Sun.

They probed the edge of the Milky Way, looking closely, for the first time, at the fringes of the galaxy about 5 million trillion kilometres from Earth.

Astrophysicist Dr Prajwal Kafle, from The University of Western Australia node of the International Centre for Radio Astronomy Research, said we have known for a while that most of the Universe is hidden.

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Dramatic New Portrait Helps Define Milky Way’s Shape, Contents


Credit: NASA/JPL-Caltech/University of Wisconsin-Madison

Credit: NASA/JPL-Caltech/University of Wisconsin-Madison

Using more than 2 million images collected by NASA’s orbiting Spitzer Space Telescope, a team of Wisconsin scientists has stitched together a dramatic 360-degree portrait of the Milky Way, providing new details of our galaxy’s structure and contents.

The new composite picture, using infrared images gathered over the last decade, was unveiled today at a TED conference in Vancouver. The galactic portrait provides an unprecedented look at the plane of our galaxy, using the infrared imagers aboard Spitzer to cut through the interstellar dust that obscures the view in visible light.

“For the first time, we can actually measure the large-scale structure of the galaxy using stars rather than gas,” explains Edward Churchwell, a University of Wisconsin-Madison professor of astronomy whose group compiled the new picture, which looks at a thin slice of the galactic plane. “We’ve established beyond the shadow of a doubt that our galaxy has a large bar structure that extends halfway out to the sun’s orbit. We know more about where the Milky Way’s spiral arms are.”

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Milky Way Amidst A ‘Council Of Giants’


We live in a galaxy known as the Milky Way – a vast conglomeration of 300 billion stars, planets whizzing around them, and clouds of gas and dust floating in between.

Though it has long been known that the Milky Way and its orbiting companion Andromeda are the dominant members of a small group of galaxies, the Local Group, which is about 3 million light years across, much less was known about our immediate neighbourhood in the universe.

Now, a new paper by York University Physics & Astronomy Professor Marshall McCall, published today in the journal Monthly Notices of the Royal Astronomical Society, maps out bright galaxies within 35-million light years of the Earth, offering up an expanded picture of what lies beyond our doorstep.

“All bright galaxies within 20 million light years, including us, are organized in a ‘Local Sheet’ 34-million light years across and only 1.5-million light years thick,” says McCall. “The Milky Way and Andromeda are encircled by twelve large galaxies arranged in a ring about 24-million light years across – this ‘Council of Giants’ stands in gravitational judgment of the Local Group by restricting its range of influence.”

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Countdown To Launch Of ESA’S Billion-Star Surveyor

October 21, 2013 Leave a comment

ESA’s billion-star surveyor Gaia will be launched from Europe’s spaceport in Kourou on 20 November to begin a five-year mission to map the stars with unprecedented precision.

Gaia’s main goal is to create a highly accurate 3D map of our Milky Way Galaxy by repeatedly observing a billion stars to determine their positions in space and their movement through it.

Other measurements will assess the vital physical properties of each star, including temperature, luminosity and composition. The resulting census will allow astronomers to determine the origin and the evolution of our Galaxy.

Gaia will map the stars from an orbit around the Sun, near a location some 1.5 million km beyond Earth’s orbit known as the L2 Lagrangian point.

The spacecraft will spin slowly, sweeping its two telescopes across the entire sky and focusing their light simultaneously onto a single digital camera, the largest ever flown in space – it has nearly a billion pixels.

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The Inside Of Our Milky Way In 3D

September 19, 2013 Leave a comment

Scientists at the Max Planck Institute for Extraterrestrial Physics have produced the first detailed three-dimensional map of the stars that form the inner regions of our Milky Way, using publicly available VVV survey data from the science archive facility at ESO. They find a box/peanut shaped bulge with an elongated bar and a prominent X-structure, which had been hinted at in previous studies. This indicates that the Milky Way was originally a pure disk of stars, which then formed a thin bar, before buckling into the box/peanut shape seen today. The new map can be used for more detailed studies of the dynamics and evolution of our Milky Way.

Our Sun resides right inside the galactic disk, about 27 000 light-years from the core of our Milky Way. Due to the obscuring effects of dense gas and dust clouds it is therefore difficult to get accurate information about the shape and properties of the inner regions of our galaxy. By using a large number of so-called “red clump” giant stars from the new VVV survey scientists at the Max Planck Institute for Extraterrestrial Physics have now produced a three-dimensional map of the galactic bulge.

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Hubble Finds Source Of Magellanic Stream


Astronomers using NASA’s Hubble Space Telescope have solved a 40-year mystery on the origin of the Magellanic Stream, a long ribbon of gas stretching nearly halfway around our Milky Way galaxy.

The Large and Small Magellanic Clouds, two dwarf galaxies orbiting the Milky Way, are at the head of the gaseous stream. Since the stream’s discovery by radio telescopes in the early 1970s, astronomers have wondered whether the gas comes from one or both of the satellite galaxies. Now, new Hubble observations reveal that most of the gas was stripped from the Small Magellanic Cloud about 2 billion years ago, and a second region of the stream originated more recently from the Large Magellanic Cloud.

“What’s interesting is that all the other nearby satellite galaxies of the Milky Way have lost their gas,” Andrew J. Fox (of the Space Telescope Science Institute in Baltimore, Md). said. “The Magellanic Clouds have been able to retain their gas and are still forming stars because they’re more massive than the other satellites. However, as they’re now approaching the Milky Way, they’re feeling its gravity more and also encountering its halo of hot gas, which puts pressure on them.”

Full Story and Images: http://hubblesite.org/newscenter/archive/releases/2013/27/full/

For The Milky Way, It’s Snack Time

October 26, 2012 Leave a comment

Yale astronomers have caught the Milky Way having a snack.

Using the Sloan Digital Sky Survey, researchers have discovered a band, or stream, of stars believed to be the remnant of an ancient star cluster slowly being ingested by the Milky Way, Earth’s home galaxy.

“The Milky Way is constantly gobbling up small galaxies and star clusters,” said Ana Bonaca, a Yale graduate student and lead author of a study forthcoming in Astrophysical Journal Letters. “The more powerful gravity of our Milky Way pulls these objects apart and their stars then become part of the Milky Way itself.”

Researchers have previously found evidence of the Milky Way eating up dwarf galaxies. Bonaca argues that the newly found stellar stream is the remnant of a star cluster rather than of a larger galaxy, because the stream is very narrow.”Our discovery is more of a light snack than a big meal for the Milky Way,” says Marla Geha, associate professor of astronomy at Yale and a co-author of the study. “Studying this digestion process in detail is important because it gives us new insight into how all galaxies form and evolve.”

Full Story: http://news.yale.edu/2012/10/25/milky-way-it-s-snack-time

Milky Way’s Black Hole Getting Ready For Snack

October 23, 2012 Leave a comment

Get ready for a fascinating eating experience in the center of our galaxy.
The event involves a black hole that may devour much of an approaching cloud of dust and gas known as G2. A supercomputer simulation prepared by two Lab physicists and a former postdoc suggests that some of G2 will survive, although its surviving mass will be torn apart, leaving it with a different shape and questionable fate.

The findings are the work of computational physicist Peter Anninos and astrophysicist Stephen Murray, both of AX division within the Weapons and Complex Integration Directorate (WCI), along with their former postdoc Chris Fragile, now an associate professor at the College of Charleston in South Carolina, and his student, Julia Wilson.

Previous simulations of the upcoming event had been done in two-dimensions, but the Cosmos++ code includes 3D capability, as well as a unique “moving mesh” enhancement, allowing the simulation to more-efficiently follow the cloud’s progression toward the black hole.

Full Story: https://www.llnl.gov/news/newsreleases/2012/Oct/NR-12-10-07.html

The Milky Way Now Has A Twin (Or Two)

August 23, 2012 Leave a comment

Image Credit: Dr Aaron Robotham, ICRAR/St Andrews using GAMA data

The Milky Way is a fairly typical galaxy on its own, but when paired with its close neighbours – the Magellanic Clouds – it is very rare, and could have been one of a kind, until a survey of our local Universe found another two examples just like us.

Astronomer Dr Aaron Robotham, jointly from the University of Western Australia node of the International Centre for Radio Astronomy Research (ICRAR) and the University of St Andrews in Scotland, searched for groups of galaxies similar to ours. “We’ve never found another galaxy system like the Milky Way before, which is not surprising considering how hard they are to spot! It’s only recently become possible to do the type of analysis that lets us find similar groups,” says Dr Robotham.

“We found about 3% of galaxies similar to the Milky Way have companion galaxies like the Magellanic Clouds, which is very rare indeed. In total we found 14 galaxy systems that are similar to ours, with two of those being an almost exact match,” says Dr Robotham.

Full Story: http://www.icrar.org/news/news_items/media-releases/the-milky-way-now-has-a-twin-or-two

Billions of Rocky Planets in Habitable Zones Around Red Dwarfs

March 28, 2012 Leave a comment

Image Credit: ESO/L. Calçada

Image Credit: ESO/L. Calçada

A new result from ESO’s HARPS planet finder shows that rocky planets not much bigger than Earth are very common in the habitable zones around faint red stars. The international team estimates that there are tens of billions of such planets in the Milky Way galaxy alone, and probably about one hundred in the Sun’s immediate neighbourhood. This is the first direct measurement of the frequency of super-Earths around red dwarfs, which account for 80% of the stars in the Milky Way.

This first direct estimate of the number of light planets around red dwarf stars has just been announced by an international team using observations with the HARPS spectrograph on the 3.6-metre telescope at ESO’s La Silla Observatory in Chile. A recent announcement (eso1204), showing that planets are ubiquitous in our galaxy used a different method that was not sensitive to this important class of exoplanets.

The HARPS team has been searching for exoplanets orbiting the most common kind of star in the Milky Way — red dwarf stars (also known as M dwarfs). These stars are faint and cool compared to the Sun, but very common and long-lived, and therefore account for 80% of all the stars in the Milky Way.

Full Story: http://www.eso.org/public/news/eso1214/