NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-06-17 T06:15:20 PDT
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For refcode 2016ApJ...827L...2P:
Retrieve 41 NED objects in this reference.
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Copyright by American Astronomical Society. Reproduced by permission
2016ApJ...827L...2P Strong Evidence for the Density-wave Theory of Spiral Structure in Disk Galaxies Pour-Imani, Hamed; Kennefick, Daniel; Kennefick, Julia; Davis, Benjamin L.; Shields, Douglas W.; Shameer Abdeen, Mohamed Abstract. The density-wave theory of galactic spiral-arm structure makes a striking prediction that the pitch angle of spiral arms should vary with the wavelength of the galaxy's image. The reason is that stars are born in the density wave but move out of it as they age. They move ahead of the density wave inside the co-rotation radius, and fall behind outside of it, resulting in a tighter pitch angle at wavelengths that image stars (optical and near-infrared) than those that are associated with star formation (far-infrared and ultraviolet). In this study we combined large sample size with wide range of wavelengths, from the ultraviolet to the infrared to investigate this issue. For each galaxy we used an optical wavelength image (B-band: 445 nm) and images from the Spitzer Space Telescope at two infrared wavelengths (infrared: 3.6 and 8.0 micron) and we measured the pitch angle with the 2DFFT and Spirality codes. We find that the B-band and 3.6 micron images have smaller pitch angles than the infrared 8.0 micron image in all cases, in agreement with the prediction of density-wave theory. We also used images in the ultraviolet from Galaxy Evolution Explorer, whose pitch angles agreed with the measurements made at 8 micron. Key words: galaxies: evolution, galaxies: fundamental parameters, galaxies: spiral, galaxies: structure
Retrieve 41 NED objects in this reference.
Please click here for ADS abstract

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