Cygnus loop

Fig. 3.29. Physical parameters and line emissivities in the post-shock gas according to a model of the Cygnus Loop SNR. Adapted from Cox (1972).

A second example of an explosion remnant is the fine lacework of the Cygnus loop, located 2500 light-years from Earth. In supersonic expansion, the gas produces shock waves that excite and ionise interstellar matter, causing it to glow. 

Emission line features in the Cygnus Loop Intensity Line energy (photonssec"1 cm 2) (keV)... 

Fig. 2. Wide band X-ray spectrum for the whole Cygnus Loop with GSPC. Superposed the best fit NEI model spectra with two Te components. region...

Previous observations so far with employing PC reported that the Cygnus Loop could be represented with a single Te component of 2 4X106K (Gorenstein et al. 1971). The high spatial observation of the Loop with the Einstein Observatory (Charles et a 1.1985) found Te in the limb to be lower than that of the interior. Vedder et al. (1986) observed a limited portion of the Loop with FPCS on the Einstein Observatory and found that the CIE condition has not been reached. Their results are 1.0 Energy(keV) shown in fig. 3 in dashed line. 

Image of a portion of the Cygnus Loop supernova remnant, taken by the Hubble space telescope. 

A view of the Cygnus Loop supernova. When all the fuel in a star is consumed, its core collapses and its outer layer explodes in a supernova. Elements through iron are formed in active stars and heavier elements are formed in supernovas. The models show H2, He, O2, P4, Sg, and Ag. 

FIGURE 21 Far-UV spectra, obtained with lUE, of diffuse nebulae, (a) Orion nebula, a typical H II region, showing continuum due to dust scattering of UV starlight, with nebular emission lines. [Reprinted with permission from Torres-Peimbert, S., et al. (1980). Astrophys. J. 293, 133.] (b) Cygnus Loop, a supernova remnant, showing emission lines due to shock-heated gas. [Reprinted with permission from Raymond, J. C., et al. (1980). Astrophys. J. 238, 881.]... 

FIGURE 22 Far-UV spectrum of a filament in the Cygnus Loop supernova remnant, obtained with the HUT in the 1990 Astro-1 shuttle mission. Emission features of O VI and other highly ionized species are revealed. [Blair, W. R, et al. (1991). Astrophys. J. 379, L33.]... 

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