Mohsen Shadmehri, Bruce G. Elmegreen
Mon. Not. R. Astron. Soc.
The number of barred (SB-type) galaxies relative to the total number of spiral galaxies in binary and group systems and in the field has been examined. Among field and group galaxies, 0.32 ± 0.09 and 0.28 ± 0.02 of all early Hubble-type spirals are SB, whereas in binary systems, 0.50 ± 0.05 are SB. There is no obvious correlation like this for intermediate and late-type galaxies. This result implies that close galaxy companions are associated with bar formation, but primarily for early Hubble-types. In addition, the relative fraction of early-type galaxies (Sa-Sb) among all types Sa-Scd is examined. Among binary SB galaxies, the early-type fraction is 0.77 ± 0.05 whereas among all SA types in any environment the early-type fraction is only 0.44 ± 0.02. Thus binary galaxies tend to be both barred and early type. Considering recent N-body simulations, we suggest that galaxy interactions produce strong spirals, which, because of their torques, lead to bar formation and a significant mass inflow in the disk. For a prolonged encounter, the mass inflow can apparently change a nonbarred galaxy of intermediate Hubble-type, Sbc-Scd, to a barred galaxy of early Hubble-type, SBa-SBb, by making the galaxy density larger in the inner region and by removing a significant amount of the gas mass and, therefore star formation, from the outer disk.
Mohsen Shadmehri, Bruce G. Elmegreen
Mon. Not. R. Astron. Soc.
Bruce G. Elmegreen
Island Universes 2005
Debra Meloy Elmegreen, Bruce G. Elmegreen, et al.
Astrophysical Journal
Trisha Ashley, Caroline E. Simpson, et al.
Astronomical Journal