Kelsey Johnson (P.I.; UVa), John Hibbard (NRAO), Sarah Gallagher (UCLA), Ann Hornschemeier (GSFC), Jane Charlton (PSU), Amanda Heiderman (NRAO-REU), et al.

This project involves Spitzer IRAC 3.6-8um and MIPS 24um observations of a sample of 12 nearby Hickson Compact Groups, chosen to sample a range of evolutionary stages. There are many aspects of this project, with different people in the above list taking charge of various scientific topics. My interest is in using the mid-IR indicators of activity to understand the evolution of the neutral hydrogen content. According to the evolutionary scenario of Verdes Montenegro et al. (2001), in less evolved compact groups the neutral hydrogen is normal or mildly deficient (compared to isolated spirals of similar Hubble Type and luminosity). In the intermediate stages, the HI is drawn into tidal features, and the group as a whole is deficient in HI. In the late stages, the spirals are highly deficient, and there is often an X-ray intergroup medium. I believe that studying this sequence will help us understand how star formation may be abruptly truncated as galaxies evolve, as suggested by some recent observations.

• Related Websites
  1. Paul Hickson's Compact Group webpage (through 1998) [DEFUNCT]
  2. Lourdes Verdes Montenegro's website of Compact Groups
  3. Spitzer/GALEX/SARA Spiral, Bridge & Tail Interacting Galaxy Sampl (Bev Smith)
  4. An HI Rogues Gallery, see esp. Figs. 154-162.
• Publications
  1. Galaxy Evolution in a Complex Environment: A Multi-wavelength Study of HCG 7, Konstantopoulos, I. S. et a., 2010, ApJ, 723, 197 (astro-ph/1007.3523)
  2. Mid-infrared Evidence for Accelerated Evolution in Compact Group Galaxies, Walker, Lisa May, Johnson, K.E., Gallagher, S. C., Hibbard, J. E., Hornschemeier, A. E., Tzanavaris, P., Charlton, J. C., Jarrett, T. H. 2010, AJ, 140, 1254 (astro-ph/1008.4581)
  3. Hierarchical Structure Formation and Modes of Star Formation in HCG 31, Gallagher, S.C. et al., 2010, AJ, 139, 545
  4. The Revealing Dust: Mid-Infrared Activity in Hickson Compact Group Galaxy Nuclei, Gallagher, S. C., Johnson, K. E., Hornschemeier, A. E., Charlton, J. C. & Hibbard, J. E. 2008, ApJ, 673, 730 (astro-ph/0710.0372)
  5. The Infrared Properties of Hickson Compact Groups, Johnson, K. E., Hibbard, J. E., Gallagher, S. C., Charlton, J. C., Hornschemeier, A. E., Jarrett, T. H. & Reines, A. E. 2007, AJ, 134, 1522 (astro-ph/0706.4461)
  6. Sarah's presentation at NNG
  7. John's ppt presentation from the ESO Workshop "Groups of galaxies in the nearby Universe", December 5-9 2005,
  8. Amandas presentation at 207th AAS
  9. Kelsey's presentation at 207th AAS