Other
Scientific paper
Jul 1978
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1978apj...223..161b&link_type=abstract
Astrophysical Journal, Part 1, vol. 223, July 1, 1978, p. 161-167. Research supported by the Science Research Council of Englan
Other
9
Astronomical Models, H Ii Regions, Nebulae, Shock Wave Propagation, Cooling, Mach Number, Numerical Integration, Spectral Line Width
Scientific paper
The structure of the cooling region behind weak shocks (speeds no more than 30 km/s, isothermal Mach number, Mzero, no more than about 3) in H II regions is determined by numerical integration. The cooling region behind the shock is too thin to be spatially resolved even in nearby H II regions. The observable quantities are, therefore, the various line strengths in the equilibrium regions ahead of and behind the shock. The line strengths can be approximately understood in terms of the effects of the compression upon their parent ionic abundances. The increase in strength of lines of the principal stage of ionization of an element is about the same as the increase in the hydrogen line strengths. For lines from stages lower than the principal stage, the increase is greater than for the hydrogen lines, and vice versa for higher stages. Qualitative criteria are given for distinguishing shocks from changes in path length or discontinuities in extinction from point to point in the nebula. The determination of Mzero from line ratios is discussed; the problem is the separation of the contribution of unshocked material superposed upon the shock. The best procedure is the simplest; obtain a lower limit to Mzero from the increase in a hydrogen line across the shock. Other, more elaborate procedures are not more accurate.
Brand Peter W. J. L.
Mathis John S.
No associations
LandOfFree
The properties of weak shocks in H II regions does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The properties of weak shocks in H II regions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The properties of weak shocks in H II regions will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1698738