Results of the summarizing process for the arXiv paper: 2207.09752v1

This review article explores the impact of stellar flybys and encounters on planet-forming discs around young stars. With most stars under 2 million years old hosting protoplanetary discs, tidal perturbations can significantly affect planet formation. The authors first examine the probability of experiencing flybys or encounters, finding that over 50% of stars with planet-forming discs in a typical star-forming environment should experience a close encounter or flyby within 1000 au. The paper then delves into the dynamical effects of different types of flybys on planet-forming discs, with prograde, parabolic, disc-penetrating flybys being the most destructive. Grazing and penetrating flybys can lead to the capture of disc material by the secondary star, forming a highly misaligned circumsecondary disc with respect to the primary's disc. One or both discs may undergo extreme accretion and outburst events similar to those observed in FU Orionis-type stars. Retrograde flybys leave distinct signatures such as warps and broken discs. The authors also review recently observed stellar systems where a stellar flyby or encounter is suspected, including UX Tau, RW Aur, AS 205, Z CMa, and FU Ori. Finally, they discuss the implications of stellar flybys for planet formation and exoplanet demographics. Possible imprints of a past flyby in our own Solar System are discussed in relation to trans-Neptunian objects' orbits and the Sun's obliquity. The paper includes detailed figures showing face-on views of gas column density for different angles (β) at various times after periastron passage during prograde encounters. The size of the disc increases with β: prograde encounters truncate it more heavily compared to retrograde ones. A bridge appears between both stars shortly after periastron for prograde orbits; remarkably for β=45° , a bridge of material connects both stars around 500 years after periastron passage. The authors also present edge-on views of the gas column density for different angles and times as well as xy- and xz-views of dust column density in centimeter-sized grains during prograde versus retrograde encounters. Overall, this review highlights the significant impact that stellar flybys can have on planet formation while providing insights into observed systems where such events may have occurred.

• Stellar flybys and encounters can significantly affect planet formation in protoplanetary discs around young stars
• Over 50% of stars with planet-forming discs in a typical star-forming environment should experience a close encounter or flyby within 1000 au
• Prograde, parabolic, disc-penetrating flybys are the most destructive while grazing and penetrating flybys can lead to the capture of disc material by the secondary star
• Retrograde flybys leave distinct signatures such as warps and broken discs
• Recently observed stellar systems where a stellar flyby or encounter is suspected include UX Tau, RW Aur, AS 205, Z CMa, and FU Ori
• Possible imprints of a past flyby in our own Solar System are discussed in relation to trans-Neptunian objects' orbits and the Sun's obliquity
• Detailed figures show face-on views of gas column density for different angles (β) at various times after periastron passage during prograde encounters. The size of the disc increases with β: prograde encounters truncate it more heavily compared to retrograde ones.
• The authors also present edge-on views of the gas column density for different angles and times as well as xy- and xz-views of dust column density in centimeter-sized grains during prograde versus retrograde encounters.
• Overall, this review highlights the significant impact that stellar flybys can have on planet formation while providing insights into observed systems where such events may have occurred.

The Impact of Stellar Flybys and Encounters on Planet-Forming Discs

Planets form from the material in protoplanetary discs around young stars. With most stars under 2 million years old hosting these discs, tidal perturbations can significantly affect planet formation. In a recent review article, researchers explored the impact of stellar flybys and encounters on planet-forming discs around young stars.

Probability of Experiencing Flybys or Encounters

The authors first examined the probability of experiencing flybys or encounters, finding that over 50% of stars with planet-forming discs in a typical star-forming environment should experience a close encounter or flyby within 1000 au. The paper then delved into the dynamical effects of different types of flybys on planet-forming discs.

Dynamical Effects

Grazing and penetrating flybys can lead to the capture of disc material by the secondary star, forming a highly misaligned circumsecondary disc with respect to the primary's disc. One or both discs may undergo extreme accretion and outburst events similar to those observed in FU Orionis-type stars. Retrograde flybys leave distinct signatures such as warps and broken discs. Prograde, parabolic, disc-penetrating flybys were found to be particularly destructive due to their ability to truncate gas columns more heavily compared to retrograde ones while also creating bridges between both stars shortly after periastron passage for prograde orbits (β=45°).

Observed Systems Suspected To Have Experienced Flyby Events

The authors reviewed recently observed stellar systems where a stellar flyby or encounter is suspected including UX Tau, RW Aur, AS 205, Z CMa, and FU Ori. They discussed possible imprints of past flyby events in our own Solar System in relation to trans-Neptunian objects' orbits and the Sun's obliquity as well as implications for exoplanet demographics and overall planet formation processes.

Figures Showing Gas Column Density at Different Angles & Times After Periastron Passage During Prograde Encounters

Detailed figures showing face-on views of gas column density for different angles (β) at various times after periastron passage during prograde encounters were included in this review article along with edge-on views of gas column density for different angles & times as well as xy & xz views of dust column density in centimeter sized grains during prograde versus retrograde encounters . These figures showed how size increases with β: prograde encounters truncate it more heavily compared to retrograde ones while also demonstrating how bridges appear between both stars shortly after periastron passage for β=45° .

Conclusion

Overall , this review highlights the significant impact that stellar flybys can have on planet formation while providing insights into observed systems where such events may have occurred .