Why the negativity?

Here are a few lines from the linked sciencemag article, with problems bolded.

Some 7 billion or 8 billion years ago, specks of stardust were ejected at escape velocity speeds from supernovae and the outer atmospheres of aging stars, some made of hardy materials such as graphite, diamond, and silicon carbide. The size of smoke particles, they lost that linear momentum and, susceptible to the gravitational attraction of nearby particles also without linear momentum drifted in space, settling in a nameless interstellar cloud.

In the next phase, that formless cloud gained angular momentum and collapsed into a disk swirling around the newborn Sun, generating frictional heat that roasted everything but those presolar grains