In the tandem planet formation regime, planets form at two distinct sites where solid particles are densely accumulated due to the on/off state of the magnetorotational instability (MRI). We found that tandem planet formation can reproduce the solid component distribution of the Solar System and tends to produce a smaller number of large planets through continuous pebble flow into the planet formation sites. In the present paper, we investigate the dependence of tandem planet formation on the

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... rtical magnetic field of the protoplanetary disk. We calculated two cases of B z ¼ 3.4 Â 10 À3 G and B z ¼ 3.4 Â 10 À5 G at 100 AU as well as the canonical case of B z ¼ 3.4 Â 10 À4 G. We found that tandem planet formation holds up well in the case of the strong magnetic field (B z ¼ 3.4 Â 10 À3 G). On the other hand, in the case of a weak magnetic field (B z ¼ 3.4 Â 10 À5 G) at 100 AU, a new regime of planetary growth is realized: the planets grow independently at different places in the dispersed area of the MRI-suppressed region of r ¼ 8À30 AU at a lower accretion rate of _ M < 10 À7:4 M 1 yr À1 . We call this the "dispersed planet formation" regime. This may lead to a system with a larger number of smaller planets that gain high eccentricity through mutual collisions. Ó 2016, China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).