Crab nebula: The crab in action & the case of the dog that did not bark

May 16, 2011
Credit: NASA/CXC/MSFC/M.Weisskopf et al

A new movie from NASA's Chandra X-ray Observatory shows a sequence of Chandra images of the Crab Nebula, taken over an interval of seven months. Dramatic variations are seen, including the expansion of a ring of X-ray emission around the pulsar (white dot near center) and changes in the knots within this ring.

However, arguably the most striking result of these observations is the variations that were not observed, or in analogy with a famous Sherlock Holmes story1, this could be a case where the fact that the dog that did not bark helps to solve a mystery.

This video is not supported by your browser at this time.
Credit: NASA/CXC/MSFC/M.Weisskopf et al & A.Hobart

The pulsar at the center of the is a neutron star that spins around about 30 times a second. It was created from a in our galaxy that was observed by astronomers in China and other countries in the year 1054.

As the young pulsar slows down, large amounts of energy are injected into its surroundings. In particular, a high-speed wind of matter and particles plows into the surrounding nebula, creating a shock wave that forms the expanding ring seen in the movie. Jets from the poles of the pulsar spew X-ray emitting matter and antimatter particles in a direction perpendicular to the ring.

The goal of these latest Chandra observations was to pinpoint the location of remarkable gamma-ray flares observed by NASA's Fermi and Italy's AGILE Satellite. A strong gamma-ray flare was observed from the Crab in September 2010, followed by an even stronger series of "superflares" in April 2011. The gamma-ray observatories were not able to locate the source of the flares within the nebula, but it was hoped that Chandra, with its high-resolution images, would.

Chandra began observing the Crab on monthly intervals beginning six days after the discovery of the gamma-ray flare in September 2010. This established a baseline of seven images of the nebula before the superflare was seen just last month.

When Fermi scientists saw that more flaring activity was beginning in April 2011, a pre-planned set of five Chandra observations was initiated. Two of these observations were made when strong gamma-ray flares occurred, but no clear evidence was seen for correlated flares in the Chandra images. The movie shows the April observations in "slow motion" to focus on the time when the gamma-ray superflares occurred. The movie shows three loops through the sequence of images, along with a timeline near the bottom.

Despite the lack of a "barking dog" in the X-ray data, these observations, as in the Sherlock Holmes story 1, will help scientists to home in on an explanation of the gamma-ray flares. The Chandra data provide strong constraints on the behavior, at relatively low energies, of the particles that have been accelerated to produce the gamma-ray flares. Another possible explanation follows if the gamma-ray flaring occurred in regions very close to the pulsar. Then they would have been missed by Chandra, because the Crab pulsar is so bright that the detectors are in essence "overexposed" so variations from that region cannot be observed. Note that in the movie an artificial source of constant brightness is included to show the position of the .

Explore further: Swirling electrons in the whirlpool galaxy

add to favorites email to friend print save as pdf

Related Stories

Fingers, Loops and Bays in the Crab Nebula

Nov 06, 2008

( -- This image gives the first clear view of the faint boundary of the Crab Nebula's X-ray-emitting pulsar wind nebula. The nebula is powered by a rapidly-rotating, highly-magnetized neutron star, ...

A young pulsar shows its hand

Apr 03, 2009

A small, dense object only twelve miles in diameter is responsible for this beautiful X-ray nebula that spans 150 light years. At the center of this image made by NASA's Chandra X-ray Observatory is a very ...

Dark energy, black holes and exploding stars

Aug 12, 2004

On Aug. 12, 1999, NASA's Chandra X-ray Observatory opened its sunshade doors for the first time, allowing celestial X-ray light to reach the observatory's mirrors. This one small step for the observatory pro ...

Recommended for you

Swirling electrons in the whirlpool galaxy

3 hours ago

The whirlpool galaxy Messier 51 (M51) is seen from a distance of approximately 30 million light years. This galaxy appears almost face-on and displays a beautiful system of spiral arms.

A spectacular landscape of star formation

9 hours ago

This image, captured by the Wide Field Imager at ESO's La Silla Observatory in Chile, shows two dramatic star formation regions in the Milky Way. The first, on the left, is dominated by the star cluster NGC ...

Exoplanet measured with remarkable precision

Aug 19, 2014

Barely 30 years ago, the only planets astronomers had found were located right here in our own solar system. The Milky Way is chock-full of stars, millions of them similar to our own sun. Yet the tally ...

New star catalog reveals unexpected 'solar salad'

Aug 19, 2014

( —An Arizona State University alumnus has devised the largest catalog ever produced for stellar compositions. Called the Hypatia Catalog, after one of the first female astronomers who lived in ...

User comments : 6

Adjust slider to filter visible comments by rank

Display comments: newest first

1 / 5 (5) May 16, 2011
Thanks for these new images of the object that powers the Crab Nebula.

The energy source seems to be neutron repulsion, the same energy source that powers the cores of the Sun, other ordinary stars, and the cores of galaxies.

Neutron Repulsion", The APEIRON Journal, in press (2011), 19 pages

With kind regards,
Oliver K. Manuel
May 17, 2011
This comment has been removed by a moderator.
1 / 5 (5) May 17, 2011
When Al Gore and the UN's IPCC figure out how to control the neutron star at the core of the Sun, they will be able to control Earth's climate.

1. "Neutron repulsion confirmed as energy source",
Journal of Fusion Energy 20, 197-201 (2003)

2. "Super-fluidity in the solar interior:
Implications for solar eruptions and climate",
Journal of Fusion Energy 21, 193-198 (2002)
1 / 5 (1) May 17, 2011
Sure looks like the torus of a dense plasma focus to me. Would explain the X-ray (and all EMF) emissions, as well as the morphology of it. Can't trust our own eyes tho, right? >.O
not rated yet May 18, 2011
Is that burst coming from the equator of the star? or how is it aligned with our perspective? I thought we were looking at the crab nebula's pulsar orthogonal to the axis?
1 / 5 (5) May 18, 2011
Is that burst coming from the equator of the star? or how is it aligned with our perspective? I thought we were looking at the crab nebula's pulsar orthogonal to the axis?

Probably we do not see the pulsar, but rapidly spinning ATOMIC material near it.

Atomic material is produced by:

a.) Neutron repulsion causes neutron emission:

Pulsar =(neutron-emission)=>free neutrons + ~10-22 MeV

b.) Neutron decay produces hydrogen

neutron =(neutron-decay)=> H + 0.782 MeV

c.) Fusion may produce He, as in the Sun

4 H =(fusion)=> He + 27 MeV

d.) etc., etc.

See: 1. "Neutron Repulsion", The
APEIRON Journal, in press, 19 pages (2011)

With kind regards,
Oliver K. Manuel
Former NASA Principal
Investigator for Apollo

1 / 5 (4) May 18, 2011
Also see:

2. "Composition of the solar interior: Information from isotope ratios",
Proceedings SOHO/GONG Conference on Helioseismology:
ESA SP-517, pp. 345-348 (2003)

With kind regards,
Oliver K. Manuel
Former NASA Principal
Investigator for Apollo