HIGH STAR FORMATION RATES IN TURBULENT ATOMIC-DOMINATED GAS IN THE INTERACTING GALAXIES IC 2163 AND NGC 2207

Journal Article · Fri May 20 00:00:00 EDT 2016 · Astrophysical Journal

DOI:https://doi.org/10.3847/0004-637X/823/1/26· OSTI ID:22666266

Elmegreen, Bruce G. ^[1]; Kaufman, Michele ^[2]; Bournaud, Frédéric; Juneau, Stéphanie ^[3]; Elmegreen, Debra Meloy ^[4]; Struck, Curtis ^[5]; Brinks, Elias ^[6]

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1. IBM Research Division, T.J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, NY 10598 (United States)
2. 110 Westchester Rd, Newton, MA 02458 (United States)
3. Laboratoire AIM-Paris-Saclay, CEA/DSM-CNRS-Université Paris Diderot, Irfu/Service d’Astrophysique, CEA Saclay, Orme des Merisiers, F-91191 Gif sur Yvette (France)
4. Department of Physics and Astronomy, Vassar College, Poughkeepsie, NY 12604 (United States)
5. Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States)
6. University of Hertfordshire, Centre for Astrophysics Research, College Lane, Hatfield AL10 9AB (United Kingdom)

CO observations of the interacting galaxies IC 2163 and NGC 2207 are combined with HI, H α , and 24 μ m observations to study the star formation rate (SFR) surface density as a function of the gas surface density. More than half of the high-SFR regions are HI dominated. When compared to other galaxies, these HI-dominated regions have excess SFRs relative to their molecular gas surface densities but normal SFRs relative to their total gas surface densities. The HI-dominated regions are mostly located in the outer part of NGC 2207 where the HI velocity dispersion is high, 40–50 km s{sup −1}. We suggest that the star-forming clouds in these regions have envelopes at lower densities than normal, making them predominantly atomic, and cores at higher densities than normal because of the high turbulent Mach numbers. This is consistent with theoretical predictions of a flattening in the density probability distribution function for compressive, high Mach number turbulence.

• OSTI ID: 22666266
• Journal Information: Astrophysical Journal, Vol. 823, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
CARBON MONOXIDE
DENSITY
DISPERSIONS
DISTRIBUTION
DISTRIBUTION FUNCTIONS
FORECASTING
GALAXIES
INTERACTIONS
MACH NUMBER
MOLECULES
STARS
SURFACES
TURBULENCE