The Nature of Turbulence in the LITTLE THINGS Dwarf Irregular Galaxies
- Department of Physics and Astronomy, Northern Arizona University, NAU Box 6010, Flagstaff, AZ 86011 (United States)
- IBM T. J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, New York, NY 10598 (United States)
- Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001 (United States)
- Department of Physics, Florida International University, CP 204, 11200 SW 8th Street, Miami, FL 33199 (United States)
We present probability density functions and higher order (skewness and kurtosis) analyses of the galaxy-wide and spatially resolved distributions of H i column density in the LITTLE THINGS sample of dwarf irregular galaxies. This analysis follows that of Burkhart et al. for the Small Magellanic Cloud (SMC). About 60% of our sample have galaxy-wide values of kurtosis that are similar to that found for the SMC, with a range up to much higher values, and kurtosis increases with integrated star formation rate. Kurtosis and skewness were calculated for radial annuli and for a grid of 32 pixel × 32 pixel kernels across each galaxy. For most galaxies, kurtosis correlates with skewness. For about half of the galaxies, there is a trend of increasing kurtosis with radius. The range of kurtosis and skewness values is modeled by small variations in the Mach number close to the sonic limit and by conversion of H i to molecules at high column density. The maximum H i column densities decrease with increasing radius in a way that suggests molecules are forming in the weak-field limit, where H{sub 2} formation balances photodissociation in optically thin gas at the edges of clouds.
- OSTI ID:
- 22663709
- Journal Information:
- Astronomical Journal (Online), Vol. 153, Issue 4; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1538-3881
- Country of Publication:
- United States
- Language:
- English
Similar Records
H i Clouds in LITTLE THINGS Dwarf Irregular Galaxies
THE STELLAR AND GAS KINEMATICS OF THE LITTLE THINGS DWARF IRREGULAR GALAXY NGC 1569