The Velocity Structure and Turbulence at the Center of the Orion Nebula
Abstract
Using the Coude Feed System of the Kitt Peak National Observatory at its highest possible dispersion and a CCD detector with wide dynamic range it was possible to examine in detail the radial and turbulent velocities of the Orion Nebula at the seeing limit. For the first time, multiple components of the spectral lines were resolved and the Gaussian profiles fit to them. Using four different observing runs, two circular areas 2 minutes in diameter were observed, the first centered on the theta^{1} Orionis and the second centered on theta^{2} Orionis. The velocity resolution of 1 km/s combined with the angular resolution of 2 seconds allowed observation in detail at line splitting as well as the location and measurement of high internal motions, about 50 km/s with respect to the bulk of ionized matter. Because over 900 different positions were measured, modern statistical techniques were used for the analysis of turbulence, so that the dispersion relation and the structure function could be calculated and compared with predictions of the Kolmogorov theory. The random motions showed correlation with spatial separation, as expected for turbulence; but comparison with predictions of the classical theory for nebular turbulence showed poor agreement. If Kolmogorov theory applies, then the energy must be input at many scales.
 Publication:

The Astrophysical Journal Supplement Series
 Pub Date:
 May 1988
 DOI:
 10.1086/191268
 Bibcode:
 1988ApJS...67...93C
 Keywords:

 Kolmogoroff Theory;
 Orion Nebula;
 Statistical Correlation;
 Turbulence;
 Velocity;
 Angular Resolution;
 Line Spectra;
 Spectral Resolution;
 Astrophysics;
 LINE PROFILES;
 NEBULAE: H II REGIONS;
 NEBULAE: INTERNAL MOTIONS;
 NEBULAE: ORION NEBULA;
 TURBULENCE