SIMBAD references

We present VLA H I observations and University of Hawaii 88 inch (2.2 m) deep optical B- and R-band observations of the IR-luminous merger Arp 299 (=NGC 3690+IC 694). These data reveal a gas-rich (M_HI=3.3x10⁹ M_☉) optically faint (µ_B≳27 mag.arcsec^–2, µ_R_≳26 mag.arcsec^–2) tidal tail with a length of over 180 kpc. The size of this tidal feature necessitates an old interaction age for the merger (≳750 Myr since first periapse), which is currently experiencing a very young starburst (≲20 Myr). The observations reveal a most remarkable structure within the tidal tail: it appears to be composed of two parallel filaments separated by approximately 20 kpc. One of the filaments is gas-rich with little if any starlight, while the other is gas-poor. We believe that this bifurcation results from a warped disk in one of the progenitors. The quantities and kinematics of the tidal H I suggest that Arp 299 results from the collision of a retrograde Sab-Sb galaxy (IC 694) and a prograde Sbc-Sc galaxy (NGC 3690) that occurred 750 Myr ago and will merge into a single object in roughly 60 Myr. We suggest that the present IR-luminous phase in this system is due in part to the retrograde spin of IC 694. Finally, we discuss the apparent lack of tidal dwarf galaxies within the tail.