No influence of passing stars on paleoclimate reconstructions over the past 56 million years

TL;DR

This study demonstrates that passing stars have no significant impact on Earth's paleoclimate over the past 56 million years when using a comprehensive solar system model.

Contribution

It shows that including detailed physics in solar system models negates the previously suggested influence of stellar flybys on paleoclimate reconstructions.

Findings

Passing stars do not affect Earth's orbital evolution in advanced models.

Even extreme stellar flyby scenarios show no impact on Earth's climate history.

Complete physics modeling is crucial for accurate assessment of stellar flybys' effects.

Abstract

Passing stars (also called stellar flybys) have notable effects on the solar system's long-term dynamical evolution, injection of Oort cloud comets into the solar system, properties of trans-Neptunian objects, and more. Based on a simplified solar system model, omitting the Moon and the Sun's quadrupole moment J2, it has recently been suggested that passing stars are also an important driver of paleoclimate before ~50 Myr ago, including a climate event called the Paleocene-Eocene Thermal Maximum (~56 Myr ago). In contrast, using a state-of-the-art solar system model, including a lunar contribution and J2, and random stellar parameters (>400 simulations), we find no influence of passing stars on paleoclimate reconstructions over the past 56 Myr. Even in an extreme flyby scenario in which the Sun-like star HD 7977 (m = 1.07 M_Sun) would have passed within ~3,900 au about 2.8 Myr ago (with 5% likelihood), we detect no discernible change in Earth's orbital evolution over the past 70 Myr, compared to our standard model. Our results indicate that a complete physics model is essential to accurately study the effects of stellar flybys on Earth's orbital evolution.