On the extinction of planetary nebulae and the turbulent structure of the Galaxy
Abstract
Fluctuations in the extinction of planetary nebulae provide strong support for the concept of a turbulent interstellar medium. The mean extinction and its variance as a function of height, z, above the galactic plane have been analyzed. The mean increases monotonically, and exponentially, to a saturation level. The variance increases as zsquared for small z and has damped oscillations for intermediate z, before levelling off at large z. The observed mean extinction and the observed variance are found to be in excellent agreement with these theoretical deductions. The spatial scale of the mean extinction is estimated to be 100 pc; the oscillation scale of the variance and the damping scale of the oscillations are estimated to be about 200 plus or minus 100 pc. The rms level of density fluctuations in the absorbing material causing the extinction is about equal to the mean value.
 Publication:

The Astronomical Journal
 Pub Date:
 January 1980
 DOI:
 10.1086/112627
 Bibcode:
 1980AJ.....85...13L
 Keywords:

 Galactic Structure;
 Interstellar Extinction;
 Interstellar Matter;
 Planetary Nebulae;
 Turbulence Effects;
 Damping;
 Fluctuation Theory;
 Saturation;
 Space Density;
 Variance (Statistics);
 Astrophysics