Formation of Planetary Systems in Binary Systems via Accretion:

https://phys.org/news/2020-03-scientists-seize-rare-chance-faraway.html

Scientists seize rare chance to watch faraway star system evolve:

At only 1% the age of the sun, the DS Tuc binary system shows us how a planet might naturally develop before its orbit is disturbed by external forces.
A young planet located 150 light-years away has given UNSW Sydney astrophysicists a rare chance to study a planetary system in the making.

The findings, recently published in the Astronomical Journal, suggest that the planet DS Tuc Ab—which orbits a star in a binary system—formed without being heavily impacted by the gravitational pull of the second star.

"We expected the pull from the second star to tilt the rotating disk of gas and dust that once surrounded the main star—a process that would skew the orbit of the planet," says Dr. Benjamin Montet, Scientia Fellow at UNSW Sydney and lead author of the study.
extract:
"Surprisingly, we found no evidence the planet's orbit was impacted. We also found the planet formed through relatively calm processes—which means it could be possible for Earth-like planets to survive in binary systems like this."
more at link.......

the paper:
https://iopscience.iop.org/article/10.3847/1538-3881/ab6d6d

The Young Planet DS Tuc Ab Has a Low Obliquity:

Abstract:
The abundance of short-period planetary systems with high orbital obliquities relative to the spin of their host stars is often taken as evidence that scattering processes play important roles in the formation and evolution of these systems. More recent studies have suggested that wide binary companions can tilt protoplanetary disks, inducing a high stellar obliquity that form through smooth processes like disk migration. DS Tuc Ab, a transiting planet with an 8.138 day period in the 40 Myr Tucana–Horologium association, likely orbits in the same plane as its now-dissipated protoplanetary disk, enabling us to test these theories of disk physics. Here, we report on Rossiter–McLaughlin observations of one transit of DS Tuc Ab with the Planet Finder Spectrograph on the Magellan Clay Telescope at Las Campanas Observatory. We confirm the previously detected planet by modeling the planet transit and stellar activity signals simultaneously. We test multiple models to describe the stellar activity-induced radial velocity variations over the night of the transit, finding the obliquity to be low: λ = 12° ± 13°, which suggests that this planet likely formed through smooth disk processes and its protoplanetary disk was not significantly torqued by DS Tuc B. The specific stellar activity model chosen affects the results at the ≈5° level. This is the youngest planet to be observed using this technique; we provide a discussion on best practices to accurately measure the observed signal of similar young planets.