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BepiColombo launch moved to 2017

Astronomy News - 31 March 2015 - 9:06am

The launch of BepiColombo, an ESA mission to explore the planet Mercury in collaboration with the Japanese space agency, JAXA, is now planned to take place during a one month long window starting on 27 January 2017.

Mercury 'painted black' by comets

Astronomy News - 31 March 2015 - 9:04am

The mystery of Mercury's dark surface can be explained by a steady dusting of carbon from passing comets, research suggests.

New insights found in black hole collisions

Astronomy News - 30 March 2015 - 9:13am

An international team of astronomers, including from the University of Cambridge, have found solutions to decades-old equations describing what happens as two spinning black holes in a binary system orbit each other and spiral in toward a collision.

The results, published in the journal Physical Review Letters, should significantly impact not only the study of black holes, but also the search for elusive gravitational waves – a type of radiation predicted by Einstein’s theory of general relativity – in the cosmos.

Unlike planets, whose average distance from the sun does not change over time, general relativity predicts that two black holes orbiting around each other will move closer together as the system emits gravitational waves.

“An accelerating charge, like an electron, produces electromagnetic radiation, including visible light waves,” said Dr Michael Kesden of the University of Texas at Dallas, the paper’s lead author. “Similarly, any time you have an accelerating mass, you can produce gravitational waves.”

The energy lost to gravitational waves causes the black holes to spiral closer and closer together until they merge, which is the most energetic event in the universe, after the big bang. That energy, rather than going out as visible light, which is easy to see, goes out as gravitational waves, which are much more difficult to detect.

While Einstein’s theories predict the existence of gravitational waves, they have not been directly detected. But the ability to ‘see’ gravitational waves would open up a new window to view and study the universe.

Optical telescopes can capture photos of visible objects, such as stars and planets, and radio and infrared telescopes can reveal additional information about invisible energetic events. Gravitational waves would provide a qualitatively new medium through which to examine astrophysical phenomena.

“Using gravitational waves as an observational tool, you could learn about the characteristics of the black holes that were emitting those waves billions of years ago, information such as their masses and mass ratios, and the way they formed” said co-author and PhD student Davide Gerosa, of Cambridge’s Department of Applied Mathematics and Theoretical Physics. “That’s important data for more fully understanding the evolution and nature of the universe.”

Later this year, upgrades to the Laser Interferometer Gravitational-Wave Observatory (LIGO) in the US and VIRGO in Europe will be completed, and the first direct measurements of gravitational waves may be just around the corner. Around the same time, the LISA Pathfinder mission will be launched as a test mission for establishing a gravitational wave detector of unprecedented sensitivity in space. 

“The equations that we solved will help predict the characteristics of the gravitational waves that LIGO would expect to see from binary black hole mergers,” said co-author Dr Ulrich Sperhake, who, along with Gerosa, is also a member of Cambridge’s Centre for Theoretical Cosmology. “We’re looking forward to comparing our solutions to the data that LIGO collects.”

The equations the researchers solved deal specifically with the spin angular momentum of binary black holes and a phenomenon called precession.

“Like a spinning top, black hole binaries change their direction of rotation over time, a phenomenon known as procession,” said Sperhake. “The behaviour of these black hole spins is a key part of understanding their evolution.”

Just as Kepler studied the motion of the earth around the sun and found that orbits can be ellipses, parabola or hyperbolae, the researchers found that black hole binaries can be divided into three distinct phases according to their rotation properties.

The researchers also derived equations that will allow statistical tracking of such spin phases, from black hole formation to merger, far more efficiently and quickly than was possible before.

“With these solutions, we can create computer simulations that follow black hole evolution over billions of years,” said Kesden. “A simulation that previously would have taken years can now be done in seconds. But it’s not just faster. There are things that we can learn from these simulations that we just couldn’t learn any other way.”

“With these tools, new insights into the dynamics of black holes will be unveiled,” said Gerosa. “Gravitational wave signals can now be better interpreted to unveil mysteries of the massive universe.”

Researchers from the Rochester Institute of Technology and the University of Mississippi also contributed to the Physical Review Letters paper. The researchers were supported in part by the Science and Technology Facilities Council, the European Commission, the National Science Foundation, UT Dallas and the University of Cambridge.

Inset image: Illustration of two rotating black holes in orbit. Both, the black hole spins (red arrows) and the orbital angular momentum (blue arrow) precess about the total angular momentum (grey arrow) in a manner that characterizes the black-hole binary system. Gravitational waves carry away energy and momentum from the system and the orbital plane (light blue) tilts and turns accordingly. Credit: Graphic by Midori Kitagawa

Adapted from University of Texas at Dallas press release.

New research provides revelations about the most energetic event in the universe — the merging of two spinning, orbiting black holes into a much larger black hole.

The behaviour of these black hole spins is a key part of understanding their evolutionUlrich SperhakeNASA's Marshall Space Flight CenterBlack Holes Go 'Mano a Mano' (NASA, Chandra, 10/06/09)

The text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

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Scorch marks left by spacecraft on Mars soon fade

Astronomy News - 30 March 2015 - 9:11am

The Red Planet cleans up our mess for us within a few years, a new study shows – which could be important for NASA's next lander

Twin Earths may lurk in our nearest star system

Astronomy News - 30 March 2015 - 9:10am

Alpha Centauri, just 4.3 light years away, may hold two planets like our own, according to observations with the Hubble Space Telescope

Planet or not, Ceres rocks

Astronomy News - 30 March 2015 - 9:09am

All eyes are on the space drama unfolding in the asteroid belt. It matters not a jot whether Ceres is a planet or a dwarf

Hubble and Chandra Discover Dark Matter Is Not as Sticky as Once Thought

Astronomy News - 27 March 2015 - 10:16am

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In particle physics labs, like the Large Hadron Collider in Geneva, Switzerland, scientists smash atoms together to study the underpinnings of matter and energy. On the scale of the macrocosm, nature provides a similar experiment by crashing clusters of galaxies together. Besides galaxies and gas, the galaxy clusters contain huge amounts of dark matter. Dark matter is a transparent form of matter that makes up most of the mass in the universe. During collisions, the clouds of gas enveloping the galaxies crash into each other and slow down or stop. Astronomers found that the dark matter continued straight through the violent collisions, without slowing down relative to the galaxies. Their best explanation is that the dark matter did not interact with visible particles, and it also interacted less frequently with other dark matter than previously thought. Astronomers used the Hubble Space Telescope and Chandra X-ray Observatory to study 72 large galaxy cluster collisions. Chandra traced the hot gas, and Hubble saw how the invisible dark matter warps space and distorts the images of background stars. This allowed for the distribution of dark matter in the collision to be mapped. The finding narrows down the options for what this dark matter might be.

Best View Yet of Dusty Cloud Passing Galactic Centre Black Hole

Astronomy News - 27 March 2015 - 10:15am
The best observations so far of the dusty gas cloud G2 confirm that it made its closest approach to the supermassive black hole at the centre of the Milky Way in May 2014 and has survived the experience. The new result from ESO’s Very Large Telescope shows that the object appears not to have been significantly stretched and that it is very compact. It is most likely to be a young star with a massive core that is still accreting material. The black hole itself has not yet shown any increase in activity.

Dark matter even darker than once thought - Hubble explores the dark side of cosmic collisions [heic1506]

Astronomy News - 27 March 2015 - 10:14am

Astronomers using observations from the NASA/ESA Hubble Space Telescope and NASA's Chandra X-ray Observatory have studied how dark matter in clusters of galaxies behaves when the clusters collide. The results, published in the journal Science on 27 March 2015, show that dark matter interacts with itself even less than previously thought, and narrow down the options for what this mysterious substance might be.

NASA’s Hubble, Chandra Find Clues that May Help Identify Dark Matter

Astronomy News - 27 March 2015 - 10:13am

Using observations from NASA’s Hubble Space Telescope and Chandra X-ray Observatory, astronomers have found that dark matter does not slow down when colliding with itself, meaning it interacts with itself less than previously thought. Researchers say this finding narrows down the options for what this mysterious substance might be.

NASA Asteroid Hunter Spacecraft Data Available to Public

Astronomy News - 27 March 2015 - 10:13am

Millions of images of celestial objects, including asteroids, observed by NASA's Near-Earth Object Wide-field Survey Explorer (NEOWISE) spacecraft now are available online to the public. The data was collected following the restart of the asteroid-seeking spacecraft in December 2013 after a lengthy hibernation.

Black holes devour stars in gulps and nibbles

Astronomy News - 27 March 2015 - 10:12am

Black holes rip stars apart and feast on them when they approach too close – but some black holes are gluttons while others play with their food

Galaxy smash-ups show dark matter wants to be alone

Astronomy News - 27 March 2015 - 10:10am

Hints that dark matter might interact with itself via a new force are dashed

Dark matter flits through collisions

Astronomy News - 27 March 2015 - 10:00am

A long-running study shows dark matter coasts unscathed through galactic collisions, betraying a ghostly lack of interaction with the known Universe.

How black holes clear galaxies of star-making gas

Astronomy News - 26 March 2015 - 10:17am

Astronomers have found proof that the strong winds blown by a supermassive black hole are dispersing the gas reservoir of its host galaxy. The new finding relies on the observation of two related phenomena in the same galaxy: a large-scale galactic outflow, seen by ESA's Herschel space observatory, and a black-hole driven wind at the galaxy's core, detected with the Japanese/US Suzaku X-ray observatory. By showing how the black hole wind is in fact driving the gas outflow that affects the entire galaxy, the discovery demonstrates the key role played by black holes in regulating the formation of stars in their host galaxies.

Bright spots on Ceres could be active ice

Astronomy News - 26 March 2015 - 10:17am

Bright spots on Ceres could be active ice

Nature 519, 7544 (2015).

Author: Alexandra Witze

Early data from Dawn spacecraft bring scientists closer to clearing up mystery about dwarf planet.

Wind from the black-hole accretion disk driving a molecular outflow in an active galaxy

Astronomy News - 26 March 2015 - 10:16am

Wind from the black-hole accretion disk driving a molecular outflow in an active galaxy

Nature 519, 7544 (2015). doi:10.1038/nature14261

Authors: F. Tombesi, M. Meléndez, S. Veilleux, J. N. Reeves, E. González-Alfonso & C. S. Reynolds

Powerful winds driven by active galactic nuclei are often thought to affect the evolution of both supermassive black holes and their host galaxies, quenching star formation and explaining the close relationship between black holes and galaxies. Recent observations of large-scale molecular outflows in ultraluminous infrared galaxies support this quasar-feedback idea, because they directly trace the gas from which stars form. Theoretical models suggest that these outflows originate as energy-conserving flows driven by fast accretion-disk winds. Proposed connections between large-scale molecular outflows and accretion-disk activity in ultraluminous galaxies were incomplete because no accretion-disk wind had been detected. Conversely, studies of powerful accretion-disk winds have until now focused only on X-ray observations of local Seyfert galaxies and a few higher-redshift quasars. Here we report observations of a powerful accretion-disk wind with a mildly relativistic velocity (a quarter that of light) in the X-ray spectrum of IRAS F11119+3257, a nearby (redshift 0.189) optically classified type 1 ultraluminous infrared galaxy hosting a powerful molecular outflow. The active galactic nucleus is responsible for about 80 per cent of the emission, with a quasar-like luminosity of 1.5 × 1046 ergs per second. The energetics of these two types of wide-angle outflows is consistent with the energy-conserving mechanism that is the basis of the quasar feedback in active galactic nuclei that lack powerful radio jets (such jets are an alternative way to drive molecular outflows).

Galaxy formation: When the wind blows

Astronomy News - 26 March 2015 - 10:16am

Galaxy formation: When the wind blows

Nature 519, 7544 (2015). doi:10.1038/519423a

Authors: James E. Geach

Astronomical observations of a luminous galaxy that has a central, mass-accreting supermassive black hole reveal how such entities launch and propel gas through galaxies at high speeds. See Letter p.436

Planetary science: Rings proposed for orbiting rock

Astronomy News - 26 March 2015 - 10:13am

Planetary science: Rings proposed for orbiting rock

Nature 519, 7544 (2015). doi:10.1038/519393a

An asteroid-sized rock orbiting between Saturn and Uranus may have a system of rings.Amanda Bosh of the Massachusetts Institute of Technology in Cambridge and her team observed the minor planet 2060 Chiron passing in front of a star, using NASA's Infrared Telescope Facility on

Mars rover detects 'useful nitrogen'

Astronomy News - 26 March 2015 - 10:12am

The Curiosity rover makes a detection of nitrogen compounds which provide further evidence that ancient Mars would have been a habitable world.