A composite illustration of the AGILE satellite and the Crab Nebula imaged by the Chandra observatory. [Image courtesy of ASI, INAF and NASA]

Crab Nebula Flares

Article Updated: 24 Dec , 2015


The Crab Nebula is one of the most popular targets for astronomers of all stripes. It is readily viewable in moderate sized amateur telescopes and wows new viewers at star parties when they’re informed they’re looking at the remnant of a supernova that exploded in 1054 AD. The nebula is also a popular target for professional astronomers looking to study physics in the environment of a pulsar. Powered by synchrotron radiation from the pulsar, the nebula glows brightly across numerous wavelengths in a steady manner that is so consistent, that astronomers have used it to calibrate instruments in different portions of the spectrum. The largest regular variation discovered was a mere 3.5% in the X-ray portion of the spectrum.

But on September 22 of 2010, the Italian Space Agency’s AGILE satellite observed a sudden brightening in the nebula in the gamma ray portion of the spectrum. The Large Area Telescope (LAT) on board the Fermi Gamma-Ray Space Telescope, which observes the Crab regularly, confirmed this flaring. Strangely, telescopes observing the nebula in other spectral regimes showed no brightening at all. The lone exception was a small knot roughly one arcsecond in diameter seen by the Chandra X-ray telescope which is believed to correspond to the base of a jet emanating from the pulsar.

Many telescopes observed the central pulsar in X-rays as well as radio to attempt to discover if there had been a sudden change in the power source itself that caused the sudden brightening, but no changes were apparent. This suggests that the flare didn’t come directly from the pulsar, but rather from the nebula itself, perhaps as an interaction between the jet and the magnetic field of the nebula causing intense synchrotron radiation. If this is the cause, then the energy of the accelerated electrons is among the highest of any astronomical event. Such a case is of interest to astronomers and physicists because it provides a rare test bed into relativistic physics and particle acceleration theory.

While this event was certainly noteworthy, it was not entirely unique. AGILE detected a previous flare on October 7, 2007 and Fermi’s LAT had discovered another in February 2009. Currently, none of these events have been entirely explained but will likely give astronomers a target for future studies. Based on the amount of coverage the Crab Nebula receives from telescopes, astronomers are no expecting that such flares are a relatively common occurrence, happening about once a year. If so, this will provide an excellent opportunity to study such events with more scrutiny.

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8 Responses

  1. Aqua says:

    Hmm… synchronicity? or just that time of the year? But last week we got some rare clear sky so there I was, ski bib, longies, fleece over a sweater under a winter weight jacket, my gloves and toupe (Hat not hair), my 4 1/2″ reflector.. and there was the Crab Nebula! Very easy to find! Make a line from the base of the bulls horns in Taurus thru Aldebaran and continue that line until you reach the next fairly bright star (Zeta in Taurus – mag. 2) then go just a little north and a little west and BINGO! I’ve seen M1 with good binoculars and steady seeing but the best views are definitely through a good telescope! One clear night, with a friend’s 24″ Dobson… I was convinced I was actually seeing waves emanating from the neutron star though no one else present could see the effect…. hmm.

    • Aqua says:

      What I saw might have been atmospheric (probable)? or more remotely possible, superluminal light reflections?

  2. Foote says:

    Funny, how there seems to be energetic shifts occurring in many other heavenly bodies all around us…

    Highest solar activity in ~11,000 years… now
    Changes to Mercuries magnetosphere as seen by MESSENGER (’08) compared to Mariner 10 (’70s ) observations….2008
    Venus – 2500% increase in active oxygen between 1978 & 1999
    Mars polar ice caps melting…. 2001
    Jupiter’s white spot merger 1997 – 2000, Intense storms in 2008
    Jupiter’s band disappearance and emergence… what, last year?
    Saturn’s plasma torus +1000%
    Saturn’s massive X-ray emissions – 2004
    Uranus featureless in 1986… storms in 1999 and some banding between this period.
    Neptune – relatively few bright clouds in 1989…
    Neptune – 40% increase in Near Infrared Range…1996 – 2002 (also significant changes in surface features)
    Pluto – 300% increase in atmospheric preasure…1989 – 2002

    For links to published research and names of discoverers/authors, please see this vid.
    http://www.youtube.com/watch?v=FqOkMaaYaAs. (v=FqOkMaaYaAs).

    For a deeper insight into the theories that suggest an explanation, check out his Event Horizon video’s.

    Hope that whatever your take on the matter, that this raises awareness to the changes happening

  3. Aqua says:

    Radio and X-ray images barely hint at the magnetic field lines within M1..


    I’d love to see a ‘magnetogram’ style image of M1’s mag. field interaction with the galactic mag. field! Say in 3D so you could do a virtual reality fly around? Did Santa leave the room?

  4. Lawrence B. Crowell says:

    The neutron star has some sort of accretion disk around it that exhibits fluctuations. This is probably a signature that some excess activity dumped more matter on the neutron star with an increase in synchrotron radiation.


  5. Paul Eaton-Jones says:

    The You Tube clip waited about 10 seconds before the phrase, “2012 scholarship”. I think that tells us all we need to know.

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