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Publication Details
AFRICAN RESEARCH NEXUS
SHINING A SPOTLIGHT ON AFRICAN RESEARCH
earth and planetary sciences
Dust-penetrated arm classes: Insights from rising and falling rotation curves
Monthly Notices of the Royal Astronomical Society, Volume 359, No. 3, Year 2005
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Description
In the last decade, near-infrared imaging has highlighted the decoupling of gaseous and old stellar discs: the morphologies of optical (Population I) tracers compared to the old stellar disc morphology, can be radically different. Galaxies which appear multi-armed and even flocculent in the optical may show significant grand-design spirals in the near-infrared. Furthermore, the optically determined Hubble classification scheme does not provide a sound way of classifying dust-penetrated stellar discs: spiral arm pitch angles (when measured in the near-infrared) do not correlate with Hubble type. The dust-penetrated classification scheme of Block & Puerari provides an alternative classification based on near-infrared morphology, which is thus more closely linked to the dominant stellar mass component. Here we present near-infrared K-band images of 14 galaxies, on which we have performed a Fourier analysis of the spiral structure in order to determine their near-infrared pitch angles and dust-penetrated arm classes. We have also used the rotation curve data of Mathewson et al. to calculate the rates of shear in the stellar discs of these galaxies. We find a correlation between near-infrared pitch angle and rate of shear: galaxies with wide open arms (the γ class) are found to have rising rotation curves, while those with falling rotation curves belong to the tightly wound α bin. The major determinant of nearinfrared spiral arm pitch angle is the distribution of matter within the galaxy concerned. The correlation reported in this study provides the physical basis underpinning spiral arm classes in the dust-penetrated regime and underscores earlier spectroscopic findings by Burstein and Rubin that Hubble type and mass distributions are unrelated. © 2005 RAS.
Authors & Co-Authors
Seigar, Marc S.
United States, Irvine
University of California, Irvine
United States, Honolulu
University Hawaii Institute for Astronomy
Block, David L.
South Africa, Johannesburg
University of the Witwatersrand
Puerari, Iv̂anio
Mexico, Puebla
Instituto Nacional de Astrofisica Optica y Electronica
Chorney, N. E.
United States, Honolulu
University Hawaii Institute for Astronomy
Canada, Victoria
University of Victoria
James, Philip A.
United Kingdom, Liverpool
Liverpool John Moores University
Statistics
Citations: 52
Authors: 5
Affiliations: 6
Identifiers
Doi:
10.1111/j.1365-2966.2005.08970.x
ISSN:
00358711
Study Design
Cross Sectional Study