Recent Results from the Spitzer Space Telescope: A New View of Galaxy Morphology and Classification

  • Giovanni G. Fazio
  • Michael A. Pahre
  • Steven P. Willner
  • Matthew L. N. Ashby
Part of the Astrophysics and Space Science Library book series (ASSL, volume 319)


The IRAC instrument on the Spitzer Space Telescope has imaged two dozen nearby galaxies. The images reveal the reddening-free spatial distributions of the stellar photospheric emission and of the warm dust in the ISM. These two components provide a new framework for galaxy morphological classification, in which the presence of spiral arms and their emission strength relative to the starlight can be measured directly and with high contrast. Four mid-infrared classification methods are explored, three of which are based on quantitative global parameters (colors, bulge-to-disk ratio) similar to those used in the past for optical studies. In this limited sample, all correlate well with traditional B-band classification.

Two lenticular galaxies exhibit warm dust emission emanating from spiral arms—an IR feature that is not apparent even in an HST color map. Spiral arms of dust in lenticular galaxies may provide evidence for an evolutionary link between them and early-type spiral galaxies.

Warm dust emission in M 81 can be traced all the way to the nucleus, unlike the near-ultraviolet emission. Finally, the presence of an AGN in M 81 can be inferred both from nuclear colors redder than the bulge and the presence of a point source at the center.


infrared galaxy classification interstellar dust 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Athey, A., Bregman, J., Temi, P., & Sauvage, M. 2002, ApJ, 571, 272ADSCrossRefGoogle Scholar
  2. Bregman, J. N., Snider, B. A., Grego, L., & Cox, C. V. 1998, ApJ, 499Google Scholar
  3. Buta, R. 1995, ApJS, 96, 39ADSCrossRefGoogle Scholar
  4. Caldwell, N. 1984, PASP, 96, 287ADSCrossRefGoogle Scholar
  5. Erwin, R & Sparke, L. S. 2003, ApJS, 146, 299ADSCrossRefGoogle Scholar
  6. Fazio, G. G.,2004, ApJS, in press (astro-ph/0405616)Google Scholar
  7. Helou, G. X.,2004, ApJS, in pressGoogle Scholar
  8. Ho, L. C., Filippenko, A. V., & Sargent, W. L. W. 1997, ApJS, 112, 315ADSCrossRefGoogle Scholar
  9. Hubble, E. P. 1926, ApJ, 64, 321ADSCrossRefGoogle Scholar
  10. Hubble, E. P. 1936, Realm of the Nebulae ( New Haven: Yale University Press )Google Scholar
  11. Jura, M., Kim, D. W., Knapp, G. R., & Guhathakurta, P. 1987, ApJ, 312, L11ADSCrossRefGoogle Scholar
  12. Knapp, G. R., Guhathakurta, P., Kim, D., &Jura, M. A. 1989, ApJS, 70, 329ADSCrossRefGoogle Scholar
  13. Kormendy, J. 1979, ApJ, 227, 714ADSCrossRefGoogle Scholar
  14. Li, A. & Draine, B. T. 2001, ApJ, 554, 778ADSCrossRefGoogle Scholar
  15. Lu, N., 2003, ApJ, 588, 199ADSCrossRefGoogle Scholar
  16. Marcum, P. M., 2001, ApJS, 132, 129ADSCrossRefGoogle Scholar
  17. Pahre, M. A., Ashby, M. L. N., Fazio, G. G., & Willner, S. P. 2004a, ApJS, in press (astroph/0405594)Google Scholar
  18. Pahre, M. A., Ashby, M. L. N., Fazio, G. G., &Willner, S. P. 2004b, ApJS, submittedGoogle Scholar
  19. Phillips, M. M., Jenkins, C. R., Dopita, M. A., Sadler, E. M., & Binette, L. 1986, AJ, 91, 1062Google Scholar
  20. Sandage, A. 1961, The Hubble Atlas of Galaxies ( Washington: Carnegie Institution )Google Scholar
  21. de Vaucouleurs, G. 1959, Handbuch der Physik, 53, 275ADSCrossRefGoogle Scholar
  22. de Vaucouleurs, G., de Vaucouleurs, A., Corwin, H. G., Buta, R. J., Paturel, G., & Fouque, P. 1991, Third Reference Catalogue of Bright Galaxies ( Springer-Verlag: New York )CrossRefGoogle Scholar
  23. Wang, Z., 2004, ApJS, in pressGoogle Scholar
  24. Werner, M. W., 2004, ApJS, this issueGoogle Scholar
  25. Willner, S. P., 2004, ApJS, in press (astro-ph/0405626)Google Scholar
  26. Xilouris, E. M., Madden, S. C., Galliano, F., Vigroux, L., & Sauvage, M. 2004, A&A, 416, 41ADSCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 2004

Authors and Affiliations

  • Giovanni G. Fazio
    • 1
  • Michael A. Pahre
    • 1
  • Steven P. Willner
    • 1
  • Matthew L. N. Ashby
    • 1
  1. 1.Harvard-Smithsonian Center for AstrophysicsCambridgeUSA

Personalised recommendations