Different Formation Scenarios of Counter-rotating Stellar Disks in
  Nearby Galaxies
  Using the integral field unit (IFU) data from Mapping Nearby Galaxies at
Apache Point Observatory (MaNGA) survey, we select a sample of 101 galaxies
with counter-rotating stellar disks and regularly-rotating ionized gas disk. We
classify the 101 galaxies into four types based on the features of their
stellar velocity fields. The relative fractions and stellar population age
radial gradients of the four types are different in blue cloud (BC), green
valley (GV) and red sequence (RS) populations. We suggest different formation
scenarios for the counter-rotating stellar disks, and the key factors in the
formation of counter-rotating stellar disks include: (1) the abundance of
pre-existing gas in progenitor, (2) the efficiency in angular momentum
consumption.
