  We study the formation of the 9:7 mean motion resonance in a system of two
low-mass planets ($m_{1}=m_{2}=3M_{\oplus}$) embedded in a gaseous
protoplanetary disk employing a full 2D hydrodynamic treatment of the
disk-planet interactions. Our aim is to determine the disk properties that
favor a capture of two equal-mass super-Earths into this second-order
resonance. For this purpose, we have performed a series of numerical
hydrodynamic simulations of the system of two super-Earths migrating in disks
with a variety of different initial parameters and found conditions for the
permanent or temporary locking in the 9:7 resonance. We observe that capture
occurs during the convergent migration of planets if their resonance angle at
the moment of arrival at the resonance assumes values in a certain range
(inside a window of capture). The width of such a window depends on the
relative migration and circularization rates that are determined by the disk
parameters. The window is wide if the relative migration rate is slow, and it
becomes narrower as the relative migration rate increases. The window will be
closed if the migration rate is sufficiently high, and the capture will not
take place. We illustrate also how the 9:7 resonance window of capture is
affected by the initial eccentricities and the initial orbits of the planets.
