* Astronomy

Blobrana · L

RE: SGR 0418+5729

Blobrana · L

SGR 0418+5729: A Hidden Population of Exotic Neutron Stars

This graphic shows an exotic object in our galaxy called SGR 0418+5729 (SGR 0418 for short). As described in our press release, SGR 0418 is a magnetar, a type of neutron star that has a relatively slow spin rate and generates occasional large blasts of X-rays.
The only plausible source for the energy emitted in these outbursts is the magnetic energy stored in the star. Most magnetars have extremely high magnetic fields on their surface that are ten to a thousand times stronger than for the average neutron star. New data shows that SGR 0418 doesn't fit that pattern. It has a surface magnetic field similar to that of mainstream neutron stars.
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Blobrana · L

Mysterious pulsar with hidden powers discovered

Dramatic flares and bursts of energy - activity previously thought reserved for only the strongest magnetized pulsars - have been observed emanating from a weakly magnetised, slowly rotating pulsar.
The international team of astrophysicists who made the discovery believe that the source of the pulsar's power may be hidden deep within its surface.
Pulsars, or neutron stars, are the collapsed remains of massive stars. Although they are on average only about 30km in diameter, they have hugely powerful surface magnetic fields, billions of times that of our Sun.
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Blobrana · L

Are most pulsars really magnetars in disguise?

Astronomers using XMM-Newton and other world-class X-ray telescopes have probed a curious source, which emits flares and bursts just like a magnetar but lacks the extremely high external magnetic field typical of these objects. The detection of this source, which could be powered by a strong, internal magnetic field hidden to observations, may mean that many 'ordinary' pulsars are dormant magnetars waiting to erupt.
Massive stars remain objects of curiosity even well after their demise. Ending their lives in dramatic fashion, as supernova explosions, they leave a very dense and compact remnant behind - a neutron star or a black hole, depending on the mass of the star. These remnants, characterised by intense gravitational fields, are the source of some extremely energetic events and give rise to a variety of interesting phenomena which can be observed throughout the entire electromagnetic spectrum.
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Blobrana · L

Observations with NASA's Chandra, Swift, and Rossi X-ray observatories, Fermi Gamma-ray Space Telescope, and ESA's XMM-Newton have revealed that a slowly rotating neutron star with an ordinary surface magnetic field is giving off bursts of X-rays and gamma rays. This discovery may indicate the presence of an internal magnetic field much more intense than the surface magnetic field, with implications for how the most powerful magnets in the cosmos evolve.
The neutron star, SGR 0418+5729, was discovered on June 5, 2009 when the Fermi Gamma-ray Space Telescope detected bursts of gamma-rays from this object. Follow-up observations four days later with the Rossi X-Ray Timing Explorer (RXTE) showed that, in addition to sporadic X-ray bursts, the neutron star exhibits persistent X-ray emission with regular pulsations that indicate that the star has a rotational period of 9.1 seconds. RXTE was able to monitor this activity for about 100 days. This behaviour is similar to a class of neutron stars called magnetars, which have strong to extreme magnetic fields 20 to 1000 times above the average of the galactic radio pulsars.
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Blobrana · L

The Gran Telescopio CANARIAS (GTC) has observed an uncommon neutron star. Classified as magnetar, its nature is as peculiar as its official name: SGR 0418+5729. The observations of the largest optical telescope of the world reached an unprecedented depth at optical wavelengths for this kind of sources, helping in constraining the physical properties of this celestial body characterised by extremely strong magnetic fields.
Neutron stars form when massive stars, between 10 to 50 times the solar mass, explode as supernova at the end of their life. While the external layers of the star are ejected into space, its nucleus collapses under its own weight with such a strong force that protons and electrons joins into neutron to occupy less space, reaching unbelievably high densities and becoming neutron stars. The density is so high that these "stellar remnants concentrate a mass comparable to the one of the Sun within the volume of a sphere of only 30 kilometres in diameter, the space occupied by a large city", points out Paolo Esposito, principal investigator of the project from the Italian Institute of Astrophysics.
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Blobrana · L

S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, P. Oleynik, M. Ulanov, D. Svinkin on behalf of the Konus-RF team, report:

The first short burst from the newly discovered SGR 0418+5729 (van der Horst et al., GCN 9499) triggered Konus-RF gamma-ray spectrometer on-board the CORONAS-PHOTON solar space observatory at 2009-06-05 T0(KRF)=74449.134 s UT (20:40:49.134).

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