The near-circular orbits of the major planets in our solar system are not directly the result of the net rotational momentum of the accretion disk at its formation. The process of planetary formation is complex and involves several factors that contribute to the final orbital configurations.
During the early stages of the solar system's formation, a rotating disk of gas and dust known as the protoplanetary disk formed around the young Sun. Over time, small solid particles within the disk collided and stuck together, gradually forming larger bodies called planetesimals. These planetesimals further accreted material and grew into protoplanets, eventually becoming the planets we see today.
The process of planet formation involved numerous random impacts, which influenced the orbital evolution of the growing bodies. These impacts can indeed contribute to the redistribution of angular momentum and orbital energy, leading to changes in the orbital characteristics of the planets. However, the exact details of how these impacts affected the final orbits are still a subject of ongoing scientific research and debate.
Jupiter, being the largest planet in our solar system, played a significant role in shaping the structure of the solar system. Its strong gravitational influence had a profound impact on the dynamics of the surrounding material, including other planets. This phenomenon, known as gravitational scattering or the "Jupiter effect," could have influenced the orbital evolution of the major planets, potentially driving some towards more circular orbits.
While Jupiter's influence may have played a role in the circularization of some orbits, it is important to note that the overall formation and evolution of the solar system involved a combination of various factors, including the initial conditions of the protoplanetary disk, interactions between growing bodies, and the effects of other planets and celestial objects. Therefore, attributing the circularity of the major planet orbits solely to Jupiter or the net rotational momentum of the accretion disk would be an oversimplification of the complex processes at play.