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Huge Outburst from a Magnetar

We get yet another example of space-based observatories complementing each other with the recent outburst of X-rays and gamma rays detected last August. The Swift satellite first noted the event on August 22, while the European Space Agency’s XMM-Newton satellite began making detailed spectral studies of the radiation twelve hours later, followed by the Integral observatory. The outburst went on for more than four months, accompanied by hundreds of smaller bursts.

The source for these events was a magnetar, a type of neutron star that is the most highly magnetized object known, with a magnetic field some 10,000 million times stronger than Earth’s. The new magnetar, christened SGR 0501+4516, is of the type known as Soft Gamma-Ray Repeaters (SGR), and is the first such found in the last decade. Magnetars are known for spectacular periods of irregular burst activity, changing their luminosity up to ten orders of magnitude on timescales of just a few milliseconds.


We occasionally discuss doomsday scenarios from nearby supernovae and the like, speculating on conditions that could limit planetary habitability, but in these troubled financial times, ESA’s own comparison may be even more dire. Speculating on what effect a magnetar at half the Moon’s distance from the Earth would have, ESA notes that its magnetic field would wipe the data off every credit card on the planet (more here).

Image: Illustration of a magnetar. Magnetars are the most intensely magnetized objects in the Universe. Their magnetic fields are some 10 000 million times stronger than Earth’s. Credit: NASA.

SGR 0501+4516, though, is about 15,000 light years away, unknown until the recent outburst. We still have much to learn about magnetars, including the crucial question of how they form. With only fifteen of them known in the Milky Way, competing ideas circulate, including the notion that a magnetar is the remaining stellar core of a highly magnetic star at the end of its life. The other suggestion involves the death of a normal star, its core accelerated in its last convulsions to provide a dynamo that strengthens its magnetic field. Both ideas are still in play.

Up next for SGR 0501+4516 is to observe it in a quiescent state, comparing these data with the results of the outburst. XMM-Newton will be on the case next year. The paper is Rea et al., “The first outburst of the new magnetar candidate SGR 0501+4516,” published online in Monthly Notices of the Royal Astronomical Society (June 12, 2009). Preprint available. Interesting to see that the paper suggests the distinction between SGRs and the other type of magnetar — Anomalous X-Ray Pulsars (AXP) — may not stand up to scrutiny. We may be on our way to unifying these sub-groups into a single family of magnetars.

Comments on this entry are closed.

  • Chris Winter June 19, 2009, 19:56

    The ESA article says: “If a magnetar were to magically appear at half the Moon’s distance from Earth, its magnetic field would wipe the details off every credit card on Earth.”

    Not to mention audio and video tape recordings, most hard disks and gyroscopes (unless they are ring laser gyros), and many scientific instruments. But I think this would be the least of our worries.

    “Magnetar outbursts can supply as much energy to Earth as solar flares, despite the fact they are far across our Galaxy…”



    “In December 2004, the magnetar SGR 1806-20 underwent such a starquake. In one-tenth of a second the subsequent blast released something like 2 times 1046 ergs of energy — equal to about 50 trillion times the Sun’s output during that same period.

    “This star sits about 50,000 light years from the Earth: literally halfway across the Milky Way galaxy from us. Yet, even from that forbidding distance, this titanic event was able to physically affect the Earth. It compressed our magnetic field and partially ionized our atmosphere, causing it to puff up measurably.

    “Mind you, it was 500 quadrillion kilometers (300 quadrillion miles) from us at the time.

    “So you can see why these things are a bit unnerving. But really, this one is so far away! Sure, it can hurt us, but at that distance really all it can do is what it did; we don’t expect it can have a bigger event, so we’re safe enough. Moreover, these objects are so bright in X-rays that we think we’ve found all the really big bruisers in the Galaxy. If one were closer to us, there’s no way to hide it. We’d see it.”

    Add to this the non-trivial problem of an object with the mass of the Sun inside the Moon’s orbit. All in all, it’s not a pleasant prospect.

  • James M. Essig June 19, 2009, 22:49

    Hi Paul;

    A magnetar may have an magnetic field of about 10 EXP 10 Tesla whereas the Earth has a magnetic field of roughly 50 x 10 EXP – 6 Tesla. The magnetic field of a magnetar can perhaps appoach 2 x 10 EXP 14 times the strength of the Earth’s magnetic field.

    The really awesome fact is that for magnetic fields within the vacuum of space, the energy stored within the field is equal to (B dot B)/[2(mu naught))] = (B dot B)/[2( 4 pi)(10 EXP – 7)]. As a result, one cubic meter of space occupied by a 1 Tesla magnetic field has about 400 kilojoules of magnetic energy. A region of space occupied by a 10 EXP 10 Tesla magnetic field has a whopping (10 EXP 10)(10 EXP 10)/[ 2 (4 pi)( 10 EXP – 7)] Joules of magnetic energy or the equivalent of about 4 x 10 EXP 25 Joules of magnetic energy. This is the equivalent of the conversion of about 400,000 tons of matter into energy or about 20,000 times the mattergy density of lead.

    If we could find a way to drop a space craft near such a star then suddenly switch on an electromagnet of the same polarity, just imagine how fast such a craft might accelerate away from the magnetar.Providing a way could be found for the craft not be destroyed in the process, jumps to extreme gamma factors in one feld swoop might be possible.

    Regardless, these extreme magnetic fields are probably useful for an intragalactic space faring civilization and so for us space heads, futher study of them makes sense.

  • ljk July 2, 2009, 11:14


    Cosmic Protons Gone Wild

    By Phil Berardelli

    ScienceNOW Daily News

    25 June 2009

    Shock waves launched into space by a supernova–the explosive death of a giant star–produce cosmic-ray particles carrying tremendous amounts of energy, astronomers have confirmed. The findings, reported today in Science, will give astronomers and physicists a better understanding of some of the universe’s more bizarre phenomena.
    Astronomers have suspected for more than a decade that supernova shock waves can act like giant particle accelerators. The basic idea is this: As the remnant of a dead star hurtles through space at up to 30 million kilometers per hour, it creates a shock wave as it interacts with the so-called interstellar medium (ISM). Protons in the shock wave get trapped by the magnetic field of the ISM, which bounces the protons back toward the remnant. But the remnant has its own magnetic field, which repels the protons.

    Each bounce adds more energy, and eventually the magnetic tennis match accelerates the protons to nearly the speed of light. Knocked free of the remnant and out into deep space, some of the protons finally hit Earth’s atmosphere. The particles are so energetic that astronauts have reported seeing flashes of light–caused by single protons striking their retinas–even when their eyes are closed.

    Now an international team of astronomers has finally observed the acceleration of protons within a shock wave. Using the Very Large Telescope in Paranal, Chile, and NASA’s Chandra spacecraft, they measured the visible light and x-ray emissions of the remnant of a supernova about 8200 light-years away in the direction of the constellation Circinus. These measurements, taken over several years, allowed them to calculate the energies of the protons behind and in front of the shock wave.

    The results suggest that the remnant’s energy accelerates protons as much as researchers had thought, says physicist and lead author Eveline Helder of Utrecht University in The Netherlands. “We did not expect such a high shock velocity,” she says, referring to the speed of the protons in the shock wave. Based on that velocity, the team concludes that more than 50% of the energy of the shock wave must be going to accelerating the protons instead of generating heat.

    It’s an important paper, says physicist Donald Ellison of North Carolina State University in Raleigh. “It confirms predictions that shocks can be extremely efficient proton accelerators,” he says, and it’s going to improve understanding “of the physics of the universe’s more exotic phenomenon,” such as gamma-ray bursts and quasars, which also produce strong shock waves, as well as supernovae.

  • Crystal July 31, 2009, 9:47

    This is an ‘interesting’ conclusion to make concerning the December 2004 magnetar blast which compressed our magnetic field and partially ionized our atmosphere, causing it to puff up measurably:
    “Sure, it can hurt us, but at that distance really all it can do is what it did; we don’t expect it can have a bigger event, so we’re safe enough. ”

    Do you not realize that the magnetar came in on the Pacific Ocean side at daybreak and hit Earth’s atmosphere at almost the exact moment that the Indonesian tsunami and quake occurred?
    Seems to me that it did a lot more damage than the ‘authorities’ would like us to believe.

  • ljk December 12, 2009, 22:25

    INTEGRAL – a status report

    Authors: Christoph Winkler

    (Submitted on 1 Dec 2009)

    Abstract: The ESA gamma-ray observatory INTEGRAL, launched on 17 October 2002, continues to produce a wealth of discoveries and new results on compact high energy Galactic objects, nuclear gamma-ray line emission, diffuse line and continuum emission, cosmic background radiation, AGN, high energy transients and sky surveys.

    The observing programme, fully open to the scientific community at large, is built from the community’s feedback to the Announcements of Opportunity, issued about once per year.

    The mission’s technical status is healthy and INTEGRAL is continuing its scientific operations well beyond its 5-year technical design lifetime. This paper will briefly summarize the overall current status.

    Comments: 8 pages, invited paper, Proc. of Workshop “The Extreme sky: Sampling the Universe above 10 keV”, Otranto (Lecce) Italy, October 13-17, 2009 Proceedings of Science, this http URL, accepted

    Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Instrumentation and Methods for Astrophysics (astro-ph.IM)

    Cite as: arXiv:0912.0077v1 [astro-ph.HE]

    Submission history

    From: Christoph Winkler [view email]

    [v1] Tue, 1 Dec 2009 11:01:06 GMT (268kb)


  • CLET December 22, 2009, 13:10

    In which constellation is the magnetar SGR 0501+4516, please ?