In-spiraling Clumps in Blue Compact Dwarf Galaxies
  Giant star-formation clumps in dwarf irregular galaxies can have masses
exceeding a few percent of the galaxy mass enclosed inside their orbital radii.
They can produce sufficient torques on dark matter halo particles, halo stars,
and the surrounding disk to lose their angular momentum and spiral into the
central region in 1 Gyr. Pairs of giant clumps with similarly large relative
masses can interact and exchange angular momentum to the same degree. The
result of this angular momentum loss is a growing central concentration of old
stars, gas, and star formation that can produce a long-lived starburst in the
inner region, identified with the BCD phase. This central concentration is
proposed to be analogous to the bulge in a young spiral galaxy. Observations of
star complexes in five local BCDs confirm the relatively large clump masses
that are expected for this process. The observed clumps also seem to contain
old field stars, even after background light subtraction, in which case the
clumps may be long-lived. The two examples with clumps closest to the center
have the largest relative clump masses and the greatest contributions from old
stars. An additional indication that the dense central regions of BCDs are like
bulges is the high ratio of the inner disk scale height to the scale length,
which is comparable to 1 for four of the galaxies.
