Toroidal wisps of a dynamic Crab
Credit: Salt Lake Astronomical Society and the Faulkes North Telescope Project, Haleakala, Maui, Hawaii taken Jan. 15, 2010
Copyright: Salt Lake Astronomical Society
Click here for feature labeled image

Our view of the structure of the dynamic Crab Nebula (Messier 1) is obscured by our two-dimensional perspective, and time, which allows us to see only a limited amount of movement.  But much can be deduced from this image -- made with the 2-meter Faulkes North Telescope -- when examined in light of other studies. This false color image reveals M1's pulsar and as well as the central cavity (light-blue).  The pulsar's movement had been "heard" by radio telescopes as it rotates at 30 times a second.  The pulsar's magnetic field generates a synchrotron disk about 1 light-year in diameter.  Movement of gas in the synchrotron disk is so swift (50% of light-speed) that changes can be detected month to month.  The synchrotron disk emits toroidal wisps of gas - seen in the image - that travel at 8% of light-speed.  Movement of the torodial wisps are detectable over an annual time scale.  The pulsar heats and stirs gas in the central cavity, contributing to the expansion of the nebula. Moving at 1160 km. per second, the nebula has reached a diameter of 10 light-years in the nearly 1 thousand years since the explosion of its progenitor star was seen in 1054 C.E.   Movement of central cavity's boundary can be seen over two decades.  Heated gas of the central cavity rises into outer dense nebula layers, cools and then falls back towards the pulsar in tube-like fingers (false-colored pink)   Spectroscopic measurement of these fingers confirms the oblate spherical shape of the Crab in three dimensions.  Most of the Crab's outer dense-gas layer is outside of the image frame. A large filamentary jet protrudes through that layer.

Related links

Jodrell Bank Centre for Astrophysics, Univ. of Manchester. 12-23-2008. The Sounds of Pulsars (audio recording of Crab pulsar). APOD. 3-26-2005. Composite Crab (composite image of puslar and synchrotron). Chandra X-Ray Observatory. 12-28-2009. Crab Nebula Movie Animations (central pulsar over two years). Faulkes Telescope Project. 2009. Crab Nebula animation - pulsar shock blasting out at almost speed of light. News Release. (O. Gomez animation assembled from 2 1/2 years of Faulkes Telescope Project archive images). APOD. 12-27-2001. The Incredible Expanding Crab (animation of two Kitt Peak M1 images taken 24 years apart). Hester, J.J., Stone, J.M, Scowen, P.A. and Jun, B. et al. 1996. WFPC2 Studies of the Crab Nebula. III. Magnetic Rayleigh-Taylor Instabilities and the Origin of the Filaments. Astrophysical J. 456:225-233 at 231 (Fig. 2 illustrates central cavity heating and cooling gas forming Rayleigh-Taylor fingers).

APOD. 10-25-2009. M1: The Crab Nebula from Hubble (detail of the tube-like Rayleigh-Tayler filaments). Space Science Institute. Dec. 1, 2005. Crab Nebula: a Dead Star Creates Celestial Havoc (showing filament jet protruding from outer wall of Crab Nebula at top of image). Fesen, R. A. and Gull, T. R. July 1986. The optical structure of the Crab Nebula's 'jet'.  Astrophysical J. 306(1):259-265 (Figure 1 shows the filamentary jet in relation to the nebula). Cadez, A., Carramiņana, A,.and Vidrih, S. July 2004. Spectroscopy and Three-Dimensional Imaging of the Crab Nebula. Astrophysical J. 609(2):797-809 (Shell is expanding at 1160 kms-1). Vidrih, Simon. 2005. Simon Vidrih Publications List (with link to Crab Nebula 3D movie). APOD. 11-22-1999. VTL-ESO Image of the Crab Nebula (similar image). ESO. 11-17-1999. Centre of the Crab Nebula in Taurus.