References

Bedogni & Woodward 1990, A&A, 231, 481.
Danforth, C., Blair, W. P. & Raymond, J. C. 1999, in prep.
Fesen, R. A., Kwitter, K. B., and Downes, R. A. 1992, AJ, 104, 719.
Hester, et al. 1996, ApJ, 456, 225.
Jun, Stone, & Norman, 1995, ApJ, 453, 322.
McKee & Cowie 1975, ApJ, 195, 715.
McKee, Cowie, & Ostriker 1978, ApJ, 219, L23.
Sgro, A. G. 1975, ApJ, 197, 621.
Spitzer, L. 1982, ApJ, 262, 315.
Stone & Norman 1992, ApJ, 390, L17.
Valzquez, et al. 1998, A&A, in prep.

 

Figure: A composite image of the Cygnus Loop H$\alpha$ courtesy of Nancy Levenson. The Northeast Filament is a classic non-radiative filament. XA and the Southeast Cloud are two good examples of cloud shock interactions.

 

Figure: a) Rayleigh-Taylor instability - a dense medium is accelerated by a light one. b) Kelvin-Helmholtz instability - velocity sheer leads to interface turbulence. Time advances to the right in each figure.

 

Figure: Calculations done by Jun, Stone and Norman (1995) show the inhibition of RT instabilities by magnetic fields. Notice the small-scale structure has vanished while the large-scale fingers are still present.

 

Figure: Six frames from one of the models of Bedogni & Woodward (1990). A spherical cloud is being struck from the left by a planar shock. In this case M=40 and $\rho_{cloud}/\rho_{ISM}=18.3$. The contours plotted are natural log of density.

 

Figure: A three dimensional numerical simulation by Stone and Norman (1992) for intermediate conditions (M=10, $\rho_{cloud}/\rho_{ISM}=10$). Displayed is a 3-D projection of log density at times equal to 0.5, 2.0 and 4.5 times the shock crossing time. See the text.

 

Figure: H$\alpha$ observation of the SE cloud in the Cygnus Loop (FKD, 1992).

 

Figure: Color image of XA in the Cygnus Loop. Red is H$\alpha$, green is [OIII], blue is the ultraviolet B5 band (1550$\AA$). Shock is incident from the right.