The velocity structure and turbulence at the center of the Orion Nebula
H. O. Castaneda;
ApJS, 1988, 67, 93
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 sup 1 Orionis and the second centered on
theta sup 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.
KEYWORDS: kolmogoroff theory, orion nebula, statistical correlation, turbulence, velocity, angular resolution, line spectra, spectral resolution
PERSOKEY:turbulence, ,
CODE: castaneda88