Secondary Infall in the Seyfert's Sextet: A Plausible Way Out of the
  Short Crossing Time Paradox
  We used integral field spectroscopy from CALIFA DR3 and multiwavelength
publicly-available data to investigate the star-formation histories of galaxies
in the Seyfert's Sextet (SS, HCG 79). The galaxies H79a, H79b, H79c, and H79f
have low star-formation rates despite showing strong signs of interaction. By
exploring their individual specific star formation histories (sSFH), we
identified three earlier episodes of strong star formation common to these four
galaxies. We use the last two episodes as markers of the epochs when the
galaxies were crossing. We suggest that after the first turn-around, initially
gas-rich galaxies crossed for the first time, consuming most of their gas.
Hence after the second turn-around most mergers from second crossings would be
mixed or dry. The exception would be gas-rich galaxies intruding for the first
time. Therefore, we suggest that SS galaxies have survived one crossing during
a Hubble time. Strong Balmer absorption lines and the presence of
counter-rotating disks provide independent bounds to the second and first
crossing, respectively. This scenario provides a plausible way out of the short
crossing time paradox.
