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Posts Tagged ‘galaxy’

Athena To Study The Hot And Energetic Universe


Artist's impression of an active galaxy. Copyright: ESA/AOES Medialab

Artist’s impression of an active galaxy. Copyright: ESA/AOES Medialab

ESA has selected the Athena advanced telescope for high-energy astrophysics as its second ‘Large-class’ science mission.

The observatory will study the hot and energetic Universe and takes the ‘L2’ slot in ESA’s Cosmic Vision 2015–25 plan, with a launch foreseen in 2028.

By combining a large X-ray telescope with state-of-the-art scientific instruments, Athena will address key questions in astrophysics, including: how and why does ordinary matter assemble into the galaxies and galactic clusters that we see today? How do black holes grow and influence their surroundings?

Scientists believe that black holes lurk at the centre of almost all galaxies and that they play a fundamental role in their formation and evolution.

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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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The Dusty Heart Of An Active Galaxy


Credit: NASA HST, News Release STScI-2000-37

Credit: NASA HST, News Release STScI-2000-37

An international research team led by Konrad Tristram from the Max-Planck-Institute for Radio Astronomy in Bonn, Germany, obtained the most detailed view so far of the warm dust in the environment of a supermassive black hole in an active galaxy. The observations of the Circinus galaxy show, for the first time, that the dust directly illuminated by the central engine of the active galaxy is located in two distinct components: an inner warped disk and a surrounding larger distribution of dust. Most likely, the larger component is responsible for most of the obscuration of the inner regions close to the supermassive black hole. Such a configuration is significantly more complex than the simple dusty doughnut, which has been favoured for the last few decades.

In active galactic nuclei, enormous amounts of energy are released due to the feeding of the supermassive black hole in the centre of the galaxy. Such black holes have masses of a million or billion times the mass of the sun. The matter spiralling in onto the black hole becomes so hot and luminous that it outshines its entire galaxy with billions of stars. The huge amounts of energy released also affect the surrounding galaxy. Active galactic nuclei are therefore thought to play an important role in the formation and evolution of galaxies and hence in the formation of the universe as presently seen.

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Hubble Watches Stars’ Clockwork Motion In Nearby Galaxy

February 19, 2014 Leave a comment

Artist's Concept. Image Credit: NASA, ESA, A. Feild and Z. Levay (STScI), Y. Beletsky (Las Campanas Observatory), and R. van der Marel (STScI)

Artist’s Concept. Image Credit: NASA, ESA, A. Feild and Z. Levay (STScI), Y. Beletsky (Las Campanas Observatory), and R. van der Marel (STScI)

Using the sharp-eyed NASA Hubble Space Telescope, astronomers have for the first time precisely measured the rotation rate of a galaxy based on the clock-like movement of its stars.

According to their analysis, the central part of the neighboring galaxy, called the Large Magellanic Cloud (LMC), completes a rotation every 250 million years. Coincidentally, it takes our Sun the same amount of time to complete a rotation around the center of our Milky Way galaxy. The arrows in this photo illustration represent the highest-quality Hubble measurements of the motion of the LMC’s stars to show how the galaxy rotates.

The Hubble team, composed of Roeland van der Marel of the Space Telescope Science Institute in Baltimore, Md., and Nitya Kallivayalil of the University of Virginia in Charlottesville, Va., used Hubble to measure the average motion of hundreds of individual stars in the LMC, located 170,000 light-years away. Hubble recorded the stars’ slight movements over a seven-year period.

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IBEX Research Shows Influence Of Galactic Magnetic Field Extends Well Beyond Our Solar System

February 13, 2014 Leave a comment

In a report published today, new research suggests the enigmatic “ribbon” of energetic particles discovered at the edge of our solar system by NASA’s Interstellar Boundary Explorer (IBEX) may be only a small sign of the vast influence of the galactic magnetic field.

IBEX researchers have sought answers about the ribbon since its discovery in 2009. Comprising primarily space physicists, the IBEX team realized that the galactic magnetic field wrapped around our heliosphere — the giant “bubble” that envelops and protects our solar system — appears to determine the orientation of the ribbon and the placement of energetic particles measured in it.

An unlikely teaming of IBEX researchers with ultra-high-energy cosmic ray physicists, however, has produced complementary insights that dovetail with IBEX’s studies to produce a more complete picture of the interactions at the solar system boundary and how they reach much farther out into the space between the stars.

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Supernova In Messier 82 Discovered By UCL Students

January 23, 2014 Leave a comment

The supernova in M 82. Credit: UCL/University of London Observatory/Steve Fossey/Ben Cooke/Guy Pollack/Matthew Wilde/Thomas Wright

The supernova in M 82.
Credit: UCL/University of London Observatory/Steve Fossey/Ben Cooke/Guy Pollack/Matthew Wilde/Thomas Wright

Students and staff at UCL’s teaching observatory, the University of London Observatory, have spotted one of the closest supernova to Earth in recent decades. At 19:20 GMT on 21 January, a team of students – Ben Cooke, Tom Wright, Matthew Wilde and Guy Pollack – assisted by Dr Steve Fossey, spotted the exploding star in nearby galaxy Messier 82 (the Cigar Galaxy).

The discovery was a fluke – a 10 minute telescope workshop for undergraduate students that led to a global scramble to acquire confirming images and spectra of a supernova in one of the most unusual and interesting of our near-neighbour galaxies.

“The weather was closing in, with increasing cloud,” Fossey says, “so instead of the planned practical astronomy class, I gave the students an introductory demonstration of how to use the CCD camera on one of the observatory’s automated 0.35–metre telescopes.”

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Hidden Details Revealed In Nearby Starburst Galaxy: Green Bank Telescope’s New Vision Debuts

December 9, 2013 Leave a comment

Composite image of starburst galaxy M82. CREDIT: Bill Saxton (NRAO/AUI/NSF); Hubble/NASA

Composite image of starburst galaxy M82. CREDIT: Bill Saxton (NRAO/AUI/NSF); Hubble/NASA

Using the new, high-frequency capabilities of the National Science Foundation’s Robert C. Byrd Green Bank Telescope (GBT), astronomers have captured never-before-seen details of the nearby starburst galaxy M82. These new data highlight streamers of material fleeing the disk of the galaxy as well as concentrations of dense molecular gas surrounding pockets of intense star formation.

M82, which is located approximately 12 million light-years away in the constellation Ursa Major, is a classic example of a starburst galaxy — one that is producing new stars tens- to hundreds-of-times faster than our own Milky Way. Its relatively nearby location made it an ideal target for the GBT’s newly equipped “W-Band” receiver, which is capable of detecting the millimeter wavelength light that is emitted by molecular gas. This new capability makes the GBT the world’s largest single-dish, millimeter-wave telescope.

“With this new vision, we were able to look at M82 to explore how the distribution of molecular gas in the galaxy corresponded to areas of intense star formation,” said Amanda Kepley, a post-doctoral fellow at the National Radio Astronomy Observatory (NRAO) in Green Bank, West Virginia, and lead author on a paper accepted for publication in the Astrophysical Journal Letters. “Having this new capability may help us understand why stars form where they do.”

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Hubble Reveals First Scrapbook Pictures Of Milky Way’s Formative Years

November 21, 2013 Leave a comment

Artist's Illustration of the Early Milky Way. Credit: NASA, ESA, and Z. Levay (STScI/AURA)

Artist’s Illustration of the Early Milky Way. Credit: NASA, ESA, and Z. Levay (STScI/AURA)

According to new Hubble Space Telescope observations of our Milky Way’s siblings, which existed long ago, the night sky must have looked much emptier in the distant past, when our galaxy was still under construction. The vast majority of our Milky Way’s stars had not yet been born. Yet the heavens were ablaze with a firestorm of new star formation.

By tracing the Milky Way’s siblings, astronomers find that our galaxy built up most of its stars between 11 billion and 7 billion years ago. The Hubble telescope’s superb resolving power allowed the researchers to study how the structure of Milky Way-like galaxies changed over time. The observations suggest that our galaxy’s flat disk and central bulge grew simultaneously into the majestic spiral galaxy of today.

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Magnetic ‘Force Field’ Shields Giant Gas Cloud During Collision With Milky Way

November 5, 2013 Leave a comment

Image: Bill Saxton, NRAO/AUI/NSF

Image: Bill Saxton, NRAO/AUI/NSF

Doom may be averted for the Smith Cloud, a gigantic streamer of hydrogen gas that is on a collision course with the Milky Way Galaxy. Astronomers using the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) and Robert C. Byrd Green Bank Telescope (GBT) have discovered a magnetic field deep in the cloud’s interior, which may protect it during its meteoric plunge into the disk of our Galaxy.

This discovery could help explain how so-called high velocity clouds (HVCs) remain mostly intact during their mergers with the disks of galaxies, where they would provide fresh fuel for a new generation of stars.

Currently, the Smith Cloud is hurtling toward the Milky Way at more than 150 miles per second and is predicted to impact in approximately 30 million years. When it does, astronomers believe, it will set off a spectacular burst of star formation. But first, it has to survive careening through the halo, or atmosphere, of hot ionized gas surrounding the Milky Way.

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The Galactic Mosh Pit

October 23, 2013 Leave a comment

It is common knowledge that our Galaxy is permanently in motion. Being a barred spiral galaxy it rotates around the Galactic centre. It has now been discovered that our Galaxy, the Milky Way, also makes small wobbling or squishing movements. It acts like a Galactic mosh pit or a huge flag fluttering in the wind, north to south, from the Galactic plane with forces coming from multiple directions, creating a chaotic wave pattern. The source of the forces is still not understood however: possible causes include spiral arms stirring things up or ripples caused by the passage of a smaller galaxy through our own.

In this study, RAVE stars were used to examine the kinematics (velocities) of stars in a large, 3D region around the Sun – the region surveys 6500 light years above and below the Sun’s position as well as inwards and outwards from the Galactic centre, reaching a quarter of the way to the centre. Using a special class of stars, red clump stars, which all have about the same brightness, mean distances to the stars could be determined. This was important as then the velocities measured with RAVE, combined with other survey data, could be used to determine the full 3D velocities (up-down, in-out and rotational). The RAVE red clump giants gave an unprecedented number of stars with which it is possible to study 3D velocities in a large region around the Sun.

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