The shapes of isolated Bok globules and embedded dense cores of molecular clouds are analyzed using a nonparametric kernel method , using the alternate hypotheses that they are randomly oriented prolate objects or that they are randomly oriented oblate objects .
In all cases , the prolate hypothesis gives a better fit to the data .
If Bok globules are oblate spheroids , they must be very flattened ; the average axis ratio is < \gamma > \approx 0.3 , and no globules can have \gamma \gtrsim 0.7 .
If Bok globules are prolate , their intrinsic flattening is not as great , with a mean axis ratio < \gamma > \approx 0.5 .
For most data samples of dense cores embedded within molecular clouds , the randomly-oriented oblate hypothesis can be rejected at the 99 \% one-sided confidence level .
If the dense cores are prolate , their mean axis ratio is in the range < \gamma > = 0.4 \to 0.5 .
Analysis of the data of Nozawa et al .
( 1991 ) reveals that dense cores are significantly different in shape from the clouds in which they are embedded .
The shapes of dense cores are consistent with their being moderately flattened prolate spheroids ; clouds have flatter apparent shapes , and are statistically inconsistent with a population of axisymmetric objects viewed at random angles .