A Classical Morphological Analysis of Galaxies in the Spitzer Survey of
  Stellar Structure in Galaxies (S4G)
  The Spitzer Survey of Stellar Structure in Galaxies (S4G) is the largest
available database of deep, homogeneous middle-infrared (mid-IR) images of
galaxies of all types. The survey, which includes 2352 nearby galaxies, reveals
galaxy morphology only minimally affected by interstellar extinction. This
paper presents an atlas and classifications of S4G galaxies in the
Comprehensive de Vaucouleurs revised Hubble-Sandage (CVRHS) system. The CVRHS
system follows the precepts of classical de Vaucouleurs (1959) morphology,
modified to include recognition of other features such as inner, outer, and
nuclear lenses, nuclear rings, bars, and disks, spheroidal galaxies, X patterns
and box/peanut structures, OLR subclass outer rings and pseudorings, bar ansae
and barlenses, parallel sequence late-types, thick disks, and embedded disks in
3D early-type systems. We show that our CVRHS classifications are internally
consistent, and that nearly half of the S4G sample consists of extreme
late-type systems (mostly bulgeless, pure disk galaxies) in the range Scd-Im.
The most common family classification for mid-IR types S0/a to Sc is SA while
that for types Scd to Sm is SB. The bars in these two type domains are very
different in mid-IR structure and morphology. This paper examines the bar,
ring, and type classification fractions in the sample, and also includes
several montages of images highlighting the various kinds of "stellar
structures" seen in mid-IR galaxy morphology.
