Universe  ID: 10708

A Flickering X-ray Candle

The Crab Nebula, created by a supernova seen nearly a thousand years ago, is one of the sky's most famous "star wrecks." For decades, most astronomers have regarded it as the steadiest beacon at X-ray energies, but data from orbiting observatories show unexpected variations, showing astronomers their hard X-ray "standard candle" isn't as steady as they once thought. From 1999 to 2008, the Crab brightened and faded by as much as 3.5 percent a year, and since 2008, it has faded by 7 percent. The Gamma-ray Burst Monitor on NASA's Fermi satellite first detected the decline, and Fermi's Large Area Telescope also spotted two gamma-ray flares at even higher energies. Scientists think the X-rays reveal processes deep within the nebula, in a region powered by a rapidly spinning neutron star — the core of the star that blew up. But figuring out exactly where the Crab's X-rays are changing over the long term will require a new generation of X-ray telescopes.

For More Information

http://www.nasa.gov/mission_pages/GLAST/news/crab-nebula-surprise.html


Credits

Scott Wiessinger (UMBC): Animator
Scott Wiessinger (UMBC): Narrator
Scott Wiessinger (UMBC): Producer
Colleen Wilson-Hodge (NASA/MSFC): Scientist
Francis Reddy (SPSYS): Writer
Please give credit for this item to:
NASA/Goddard Space Flight Center. However, each image should be credited as indicated above.

Science Paper:
http://iopscience.iop.org/2041-8205/727/2/L40/pdf/apjl_727_2_40.pdf

Short URL to share this page:
http://svs.gsfc.nasa.gov/10708

Missions:
Fermi Gamma-ray Space Telescope
RXTE
Swift

Data Used:
Fermi
Swift
Fermi/LAT
Note: While we identify the data sets used in these visualizations, we do not store any further details nor the data sets themselves on our site.

This item is part of these series:
Narrated Movies
Fermi
Goddard Shorts
Astrophysics Stills
Astrophysics Features

Goddard TV Tape:
G2011-005 -- Crab Nebula Variability

Keywords:
SVS >> HDTV
SVS >> Neutron Star
SVS >> Satellite
SVS >> X-ray
GCMD >> Earth Science >> Spectral/Engineering >> Gamma Ray
SVS >> Pulsar
SVS >> Swift
SVS >> Fermi
DLESE >> Narrated
SVS >> Supernova
SVS >> Star
SVS >> Nebula
SVS >> RXTE
NASA Science >> Universe

GCMD keywords can be found on the Internet with the following citation: Olsen, L.M., G. Major, K. Shein, J. Scialdone, S. Ritz, T. Stevens, M. Morahan, A. Aleman, R. Vogel, S. Leicester, H. Weir, M. Meaux, S. Grebas, C.Solomon, M. Holland, T. Northcutt, R. A. Restrepo, R. Bilodeau, 2013. NASA/Global Change Master Directory (GCMD) Earth Science Keywords. Version 8.0.0.0.0