  We measure the power spectrum of HI intensity fluctuations in the extremely
faint (M_B ~ -10.9) dwarf galaxy DDO 210 using a visibility based estimator
that is well suited in very low signal to noise ratio regimes. DDO 210's HI
power spectrum is well fit by a power law $P_HI(U)= A U^{\alpha}$ with
$\alpha=-2.75 \pm0.45$ over the length-scales 80 pc to 500 pc. We also find
that the power spectrum does not change with an increase in the velocity
channel width, indicating that the measured fluctuations correspond mainly to
density fluctuations. However, Kolmogorov turbulence (with a velocity structure
function spectral slope of 2/3) cannot be ruled out from the present
observations. The value of the slope $\alpha$ is similar to that obtained in
the Milkyway. In contrast to the Milkyway, DDO 210 has three orders of
magnitude less HI, no spiral arms, and also no measurable ongoing star
formation. The fact that the power spectrum slope is nonetheless similar in
these two galaxies (and also similar to the values measured for the LMC and
SMC) suggests that there is some universal, star formation independent,
phenomenon responsible for producing fine scale structure in the gas.

Astrophysics