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Posts Tagged ‘neutron stars’

NASA’s Fermi Satellite Finds Hints Of Starquakes In Magnetar ‘Storm’

October 24, 2014 Leave a comment

Image Credit: NASA's Goddard Space Flight Center/S. Wiessinger

Image Credit: NASA’s Goddard Space Flight Center/S. Wiessinger

NASA’s Fermi Gamma-ray Space Telescope detected a rapid-fire “storm” of high-energy blasts from a highly magnetized neutron star, also called a magnetar, on Jan. 22, 2009. Now astronomers analyzing this data have discovered underlying signals related to seismic waves rippling throughout the magnetar.

Such signals were first identified during the fadeout of rare giant flares produced by magnetars. Over the past 40 years, giant flares have been observed just three times — in 1979, 1998 and 2004 — and signals related to starquakes, which set the neutron stars ringing like a bell, were identified only in the two most recent events.

“Fermi’s Gamma-ray Burst Monitor (GBM) has captured the same evidence from smaller and much more frequent eruptions called bursts, opening up the potential for a wealth of new data to help us understand how neutron stars are put together,” said Anna Watts, an astrophysicist at the University of Amsterdam in the Netherlands and co-author of a new study about the burst storm. “It turns out that Fermi’s GBM is the perfect tool for this work.”

Link To Full Story And Video

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With A Deadly Embrace, ‘Spidery’ Pulsars Consume Their Mates

February 24, 2014 Leave a comment

Artist's concept. Image Credit: NASA's Goddard Space Flight Center

Artist’s concept. Image Credit: NASA’s Goddard Space Flight Center

Black widow spiders and their Australian cousins, known as redbacks, are notorious for their tainted love, expressed as an unsettling tendency to kill and devour their male partners. Astronomers have noted similar behavior among two rare breeds of binary system that contain rapidly spinning neutron stars, also known as pulsars.

“The essential features of black widow and redback binaries are that they place a normal but very low-mass star in close proximity to a millisecond pulsar, which has disastrous consequences for the star,” said Roger Romani, a member of the Kavli Institute for Particle Astrophysics and Cosmology, an institute run jointly by Stanford and SLAC National Accelerator Laboratory in Menlo Park, Calif. Black widow systems contain stars that are both physically smaller and of much lower mass than those found in redbacks.

So far, astronomers have found at least 18 black widows and nine redbacks within the Milky Way, and additional members of each class have been discovered within the dense globular star clusters that orbit our galaxy.

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Neutron Stars In The Computer Cloud: Einstein@Home Discovers 24 New Pulsars In Archival Data

August 29, 2013 Leave a comment

The combined computing power of 200,000 private PCs helps astronomers take an inventory of the Milky Way. The Einstein@Home project connects home and office PCs of volunteers from around the world to a global supercomputer. Using this computer cloud, an international team lead by scientists from the Max Planck Institutes for Gravitational Physics and for Radio Astronomy analysed archival data from the CSIRO Parkes radio telescope in Australia. Using new search methods, the global computer network discovered 24 pulsars – extraordinary stellar remnants with extreme physical properties. These can be used as testbeds for Einstein’s general theory of relativity and could help to complete our picture of the pulsar population.

“We could only conduct our search thanks to the enormous computing power provided by the Einstein@Home volunteers,” says Benjamin Knispel, researcher at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute/AEI) in Hannover, and lead author of the study now published in The Astrophysical Journal. “Through the participation of the public, we discovered 24 new pulsars in our Milky Way, which had previously been missed – and some of them are particularly interesting.”

Full Story: http://www.aei.mpg.de/480062/Einstein_Home_24PSRs_PMPS
Einstein@Home Home Page: http://einstein.phys.uwm.edu

Earth’s Gold Came From Colliding Dead Stars


Artist's conception. Credit: Dana Berry, SkyWorks Digital, Inc.

Artist’s conception. Credit: Dana Berry, SkyWorks Digital, Inc.

We value gold for many reasons: its beauty, its usefulness as jewelry, and its rarity. Gold is rare on Earth in part because it’s also rare in the universe. Unlike elements like carbon or iron, it cannot be created within a star. Instead, it must be born in a more cataclysmic event – like one that occurred last month known as a short gamma-ray burst (GRB). Observations of this GRB provide evidence that it resulted from the collision of two neutron stars – the dead cores of stars that previously exploded as supernovae. Moreover, a unique glow that persisted for days at the GRB location potentially signifies the creation of substantial amounts of heavy elements – including gold.

“We estimate that the amount of gold produced and ejected during the merger of the two neutron stars may be as large as 10 moon masses – quite a lot of bling!” says lead author Edo Berger of the Harvard-Smithsonian Center for Astrophysics (CfA).

Full Story: http://www.cfa.harvard.edu/news/2013/pr201319.html

Blitzars: Fast Radio Bursts From Supramassive Rotating Neutron Stars


Image Credit: Nasa

Image Credit: Nasa

Radio telescopes have picked up some bright radio flashes that appear for only a brief moment on the sky and do not repeat (Thornton et al. 2013, Science). So, what causes these unusual radio signals? We suggest in a recent paper (Falcke & Rezzolla 2013, ArXiv.org) that this could be the final farewell greetings of a supramassive rotating neutron star (SURON) collapsing into a black hole and shedding its magnetic field.

Full Story: http://www.astro.ru.nl/~falcke/PR/blitzar/

The Violent Birth Of Neutron Stars


A team of researchers at the Max Planck Institute for Astrophysics conducted the most expensive and most elaborate computer simulations so far to study the formation of neutron stars at the center of collapsing stars with unprecedented accuracy. These worldwide first three-dimensional models with a detailed treatment of all important physical effects confirm that extremely violent, hugely asymmetric sloshing and spiral motions occur when the stellar matter falls towards the center. The results of the simulations thus lend support to basic perceptions of the dynamical processes that are involved when a star explodes as supernova.

Stars with more than eight to ten times the mass of our Sun end their lives in a gigantic explosion, in which the stellar gas is expelled into the surrounding space with enormous power. Such supernovae belong to the most energetic and brightest phenomena in the universe and can outshine a whole galaxy for weeks. They are the cosmic origin of chemical elements like carbon, oxygen, silicon, and iron, of which the Earth and our bodies are made of, and which are bred in massive stars over millions of years or freshly fused in the stellar explosion.

Supernovae are also the birth places of neutron stars, those extraordinarily exotic, compact stellar remnants, in which about 1.5 times the mass of our Sun is compressed to a sphere with the diameter of Munich. This happens within fractions of a second when the stellar core implodes due to the strong gravity of its own mass. The catastrophic collapse is stopped only when the density of atomic nuclei – gargantuan 300 million tons in a sugar cube – is exceeded.

Full Story: http://www.mpa-garching.mpg.de/mpa/institute/news_archives/news1306_ddd/news1306_ddd-en.html

The University Of Alicante Finds The First Evidence Of A New Phase In Neutron Stars


A study led by the University of Alicante, in which in the National Research Council (CSIC) has participated, has detected what may be the first observational evidence of existence of a new exotic phase of matter in the inner crust of neutron stars (pulsars).

The latest issue of Nature Physics shows the results of a research project that addresses one of the unknowns in the field of X-ray pulsars, the existence of a limit higher than 12 seconds in the rotation periods of isolated neutron stars. This limit is actually due to the existence of new exotic phases of matter. Pulsars are neutron stars (ultracompact and strongly magnetized stars) in rotation, which emit electromagnetic radiation with amazing precision in their periodicity.

As José A. Pons says, lecturer at the University of Alicante’s Relativistic Astrophysics Group and Director of the Department of Applied Physics, who led the work: “This may be the first observational evidence of existence of the phase of nuclear ‘pasta’ inside neutron stars, which may allow that future missions of X-ray observatories can be used to define aspects of how nuclear interaction works, which is not yet entirely clear”.

Nuclear Pasta, named for its resemblance to the Italian pasta, occurs when the combination of nuclear and electromagnetic forces, at densities close to the atomic nuclei, favours the ordering of the nucleons (protons and neutrons) in non-spherical shapes , as sheets or filaments (lasagna or spaghetti).

Full Story: http://www.alphagalileo.org/ViewItem.aspx?ItemId=132027&CultureCode=en