HIGH-RESOLUTION H I DISTRIBUTIONS AND MULTI-WAVELENGTH ANALYSES OF MAGELLANIC SPIRALS NGC 4618 AND NGC 4625

Journal Article · Wed Aug 15 04:00:00 EDT 2012 · Astronomical Journal (New York, N.Y. Online)

DOI:https://doi.org/10.1088/0004-6256/144/2/67· OSTI ID:22034374

Kaczmarek, Jane F ^[1]

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1. Now at Sydney Institute for Astronomy, School of Physics A29, The University of Sydney, NSW 2006 (Australia)

We present a detailed analysis of high-resolution H I observations of the Magellanic spiral galaxies NGC 4618 and NGC 4625. While the H I disk of NGC 4625 is remarkably quiescent with a nearly uniform velocity dispersion and no evidence of H I holes, there is a dynamic interplay between star formation and the distribution of neutral hydrogen in NGC 4618. We calculate the critical density for widespread star formation in each galaxy and find that star formation proceeds even where the surface density of the atomic gas is well below the critical density necessary for global star formation. There are strong spatial correlations in NGC 4618 between UV emission, 1.4 GHz radio continuum emission, and peaks in the H I column density. Despite the apparent overlap of the outer disks of the two galaxies, we find that they are kinematically distinct, indicating that NGC 4618 and NGC 4625 are not interacting. The structure of NGC 4618 and, in particular, the nature of its outer ring are highly suggestive of an interaction, but the timing and nature of such an interaction remain unclear.

• OSTI ID: 22034374
• Journal Information: Astronomical Journal (New York, N.Y. Online), Journal Name: Astronomical Journal (New York, N.Y. Online) Journal Issue: 2 Vol. 144; ISSN 1538-3881
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ASTRONOMY
ASTROPHYSICS
CORRELATIONS
DENSITY
EMISSION SPECTROSCOPY
GHZ RANGE
HYDROGEN
MAGELLANIC CLOUDS
PHOTON EMISSION
RESOLUTION
SPATIAL DISTRIBUTION
STARS
ULTRAVIOLET SPECTRA