A → galaxy bulge that shows
a boxy or peanut-like morphology. These bulges are usually featureless and show no signs
of → dust obscuration,
young → stellar populations,
or → star-forming regions.
They are also kinematically cold and usually referred to as
→ pseudo-bulges. A number of studies have shown that these structures
are just the inner parts of → bars
that grow vertically thick due to vertical → resonances.
They have basically the same dynamics and stellar content
as bars, just their geometry is somewhat different. Box/peanut bulges are not seen
if the galaxy is not inclined enough. In a → face-on galaxy,
if it has a box/peanut, it will be seen as part of the bar. The
→ Milky Way shows a box/peanut bulge. Another remarkable case
is that of → M31, known to have a bar, with its box/peanut inner part
(Combes & Sanders 1981, A&A 96, 164; Combes et al. 1990, A&A 233, 82;
Kormendy & Kennicutt, 2004, ARA&A 42, 603).
See also: → box; → peanut;
→ bulge.
