Grand design and flocculent spirals in the Spitzer Survey of Stellar Structure in Galaxies (S4G)

Debra Meloy Elmegreen, Bruce G. Elmegreen, Andrew Yau, E. Athanassoula, Albert Bosma, Ronald J. Buta, George Helou, Luis C. Ho, Dimitri A. Gadotti, Johan H. Knapen, Eija Laurikainen, Barry F. Madore, Karen L. Masters, Sharon E. Meidt, Karin Menendez-Delmestre, Michael W. Regan, Heikki Salo, Kartik Sheth, Dennis Zaritsky, Manuel AravenaRamin Skibba, Joannah L. Hinz, Jarkko Laine, Armando Gil de Paz, Juan-Carlos Munoz-Mateos, Mark Seibert, Trisha Mizusawa, Taehyun Kim, Santiago Erroz Ferrer

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Abstract

Spiral arm properties of 46 galaxies in the Spitzer Survey of Stellar Structure in Galaxies (S4G) were measured at 3.6 μm, where extinction is small and the old stars dominate. The sample includes flocculent, multiple arm, and grand design types with a wide range of Hubble and bar types. We find that most optically flocculent galaxies are also flocculent in the mid-IR because of star formation uncorrelated with stellar density waves, whereas multiple arm and grand design galaxies have underlying stellar waves. Arm-interarm contrasts increase from flocculent to multiple arm to grand design galaxies and with later Hubble types. Structure can be traced further out in the disk than in previous surveys. Some spirals peak at mid-radius while others continuously rise or fall, depending on Hubble and bar type. We find evidence for regular and symmetric modulations of the arm strength in NGC 4321. Bars tend to be long, high amplitude, and flat-profiled in early-type spirals, with arm contrasts that decrease with radius beyond the end of the bar, and they tend to be short, low amplitude, and exponential-profiled in late Hubble types, with arm contrasts that are constant or increase with radius. Longer bars tend to have larger amplitudes and stronger arms.
Original languageEnglish
JournalThe Astrophysical Journal
Volume737
Issue number1
DOIs
Publication statusPublished - 10 Aug 2011

Keywords

  • galaxies: photometry
  • galaxies: spiral
  • galaxies: structure
  • infrared: galaxies

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