An early-type galaxy with an inner star-forming disk
  Early-type galaxies (ETGs) are composed of two distinct populations:
high-mass and low-mass, which are likely to be built via gas-poor merging and
gas-rich merging/accretion, respectively. However, it is difficult to directly
associate low-mass ETGs with gas-rich processes, because currently they are gas
poor with no signs of ongoing star formation. We report a discovery of an ETG
(SDSS J142055.01+400715.7) with Mstellar=10^10 Msun that offers direct evidence
for gas-rich merging as the origin of low-mass ETGs. The integrated properties
of the galaxy are consistent with a typical low-mass ETG, but the outer and
inner regions show distinct dispersion- and rotation-dominated kinematics,
respectively. There are some tidal features surrounding the galaxy. These two
facts suggest very recent galaxy merging. Furthermore, the inner disk harbors
on-going star formation, indicating the merging to be gas rich. This type of
galaxy is rare but it may be a demonstration of the role the transient phase of
gas-rich merging plays in making a low-mass ETG.
