Der solare Masseverlust hat anscheinend viel größere Auswirkungen auf die langfristige Entwicklung der Planetenbahnen, als man bislang angenommen hatte. Dazu braucht es auch keinen Masseverlust von 50%, welcher zur völligen Auflösung der gravitativen Bindung führen würde, siehe Post #13 oben. Wie in der kürzlich publizierten Arbeit von Batygin et al. (siehe Post #10) gezeigt wird, haben nämlich die zu erwartenden starken Unregelmäßigkeiten im Masseverlust beim Übergang der Sonne zur und während der Rote Riesen Phase gravierende Auswirkungen auf die Stabilität der Planetenbahnen:
Konstantin Batygin, Jim Fuller, and Fred C. Adams: Terminal Instability of the Solar System Triggered by Stochastic Solar Mass Loss
From its birth, celestial mechanics has been deeply intertwined with the question of the solar system’s dynamical stability. For the inner planets, this question is now statistically settled: Mercury’s orbit carries a ∼1% chance of destabilization before the Sun leaves the main sequence. The outer solar system has seemed more secure, with its intrinsic dynamical lifetime estimated at ∼10^18 yr. Even accounting for the Sun’s mass loss and stellar flybys, the orbital architecture of the giant planets had been expected to persist for ∼100 Gyr. Here we show that these estimates rest on the assumption that solar mass loss is smooth. The recently measured white dwarf recoil demands asymmetric mass loss that is most readily attributed to discrete, independently directed ejections that impulsively perturb stellar motion. As the Sun sheds its envelope in such parcels, the planets’ orbits random-walk with amplitude set by the mass-loss granularity. At a coarseness corresponding to observationally permitted kicks, this stochastic forcing restructures the outer solar system concurrently with the Sun’s death. In particular, our numerical experiments reveal that orbit crossings can commence on the red giant branch, with ∼40% of realizations undergoing disruption or violent scattering before the white dwarf forms and ∼90% self-destructing within 3 Gyr. The outer solar system’s dynamical lifetime thus collapses from 10^18 yr to approximately a gigayear after white dwarf formation.
S&T - The Sun Has a New Life Expectancy, and It’s a Billion Times Shorter
New simulations suggest that the planets’ orbits will destabilize well before the Sun expands into its red giant phase.
Several studies have investigated what will happen to the orbits of planets in our solar system as the Sun sheds its mass during its transition to a white dwarf. These studies have found that while the semimajor axes of the planets will expand by approximately a factor of 2, their orbits remain stable on timescales longer than the age of the universe (approximately 1018 years). This expanded orbital architecture will make the solar system more prone to jostles from stellar flybys, but even accounting for this, the giant planets’ orbits wouldn’t disassemble for another 30–100 billion years.
However, all of these studies modeled solar mass loss as a smooth function, so the dismantling of the solar system was left up to external forcings. In reality, stars on the red giant branch undergo mass ejections that are random in time and direction, corresponding to velocity “kicks” that can alter the dynamics of the planets.
A team led by Konstantin Batygin at the California Institute of Technology conducted numerical experiments to analyze the orbital dynamics of the outer solar system under different solar mass-loss conditions. First, they tested the classic case of smooth mass loss and validated previous findings that, despite planetary orbits doubling in size, the dynamics are pretty tame. This holds true even when mass is ejected anisotropically: if the timing is smooth, the asymmetries cancel out.
Outer Solar System, Your Days Are Numbered
Next, they simulated stochastic kicks and found that the behavior of the outer planets was largely tied to the ejection mass of each kick. For very small ejection masses (≤ 10^-7 M☉), dynamics mimic the smooth mass-loss case. For intermediate values (10^-7 to 10^-6 M☉), there’s a roughly 20% chance Jupiter–Saturn and Uranus–Neptune enter mean-motion resonances: an orbital configuration where planets’ periods are a ratio of small integers. These resonant configurations don’t protect the giant planets, however: resonant simulations disassemble slightly more often than nonresonant simulations. For larger ejection masses (≥ 10^-5 M☉), the outer solar system disassembles on the timescale of billions of years.
Which ejection masses are the most accurate for our Sun? Well, unfortunately for our beloved outer planets, ejection models and observed kick amplitudes suggest a future ejection mass of 10-4 M☉. With kicks like these, not only is there a considerable chance of orbit destabilization, but it could happen before the white dwarf even forms. About 40% of simulations lead to disruption or violent scattering while the Sun is in its red giant phase, and roughly 90% break down within 3 billion years.
This new discovery reduces the life expectancy of the solar system from one billion billion years to a meager one billion years after white dwarf formation.
Gruß, Peter
), dass unsere Sonne jede Sekunde etwa 600 Millionen Tonnen Wasserstoff zu 596 Millionen Tonnen Helium verschmilzt. Die Differenz von vier Millionen Tonnen wird als Strahlungsenergie abgegeben. Im Laufe ihres bisherigen Daseis hat die Sonne auf diese Weise etwa die Masse von Saturn umgesetzt.
