Minimal conditions for survival of technological civilizations in the face of stellar evolution

Abstract

The ease of interstellar rocket travel is an issue with implications for the long term fate of our own and other civilizations and for the much-debated number of technological civilizations in the Galaxy. We show that the physical barrier to interstellar travel can be greatly reduced if voyagers are patient, and wait for the close passage of another star. For a representative time of $\sim$1 Gyr, characteristic of the remaining time that Earth will remain habitable, one anticipates a passage of another star within $\sim 1500$~AU. This lowers the travel time for interstellar migration by $\sim$ two orders of magnitude compared with calculated travel times based on distances comparable to average interstellar separations (i.e., $\sim$1 pc) in the solar vicinity. We consider the implications for how long-lived civilizations may respond to stellar evolution, including the case of stars in wide binaries, and the difficulties of identifying systems currently undergoing a relevant close encounter. Assuming that life originates only around G-type stars, but migrates primarily to lower mass hosts when the original system becomes uninhabitable, the fraction of extant technological civilizations that exist as diaspora can be comparable to the fraction that still orbit their original host stars.

9 pages, 0 figures, to appear in the Astronomical Journal

References in corpus (13)

• The Occurrence and Mass Distribution of Close-in Super-Earths, Neptunes, and Jupiters
• A Re-appraisal of the Habitability of Planets Around M Dwarf Stars
• Kepler-62: A five-planet system with planets of 1.4 and 1.6 Earth radii in the Habitable Zone
• The Occurrence of Rocky Habitable Zone Planets Around Solar-Like Stars from Kepler Data
• A Statistical Reconstruction of the Planet Population Around Kepler Solar-Type Stars
• Influence of Stellar Multiplicity On Planet Formation. II. Planets Are Less Common in Multiple-Star Systems with Separations Smaller than 1500 AU
• Synthesizing Exoplanet Demographics from Radial Velocity and Microlensing Surveys, II: The Frequency of Planets Orbiting M Dwarfs
• The Ĝ Infrared Search for Extraterrestrial Civilizations with Large Energy Supplies. I. Background and Justification
• The Occurrence of Wide-Orbit Planets in Binary Star Systems
• The stellar velocity distribution function in the Milky Way galaxy
• Accounting for Multiplicity in Calculating Eta Earth
• A search for technosignatures from TRAPPIST-1, LHS 1140, and 10 planetary systems in the Kepler field with the Green Bank Telescope at 1.15-1.73 GHz
• 8 in 10 Stars in the Milky Way Bulge Experience Stellar Encounters Within 1000 AU in a Gigayear

Cited by in corpus (7)

• The Case for Technosignatures: Why They May Be Abundant, Long-lived, Highly Detectable, and Unambiguous
• Infrared and Optical Detectability of Dyson Spheres at White Dwarf Stars
• Unbound Close Stellar Encounters in the Solar Neighborhood
• Galactic Traversability: A New Concept for Extragalactic SETI
• Galactic settlement of low-mass stars as a resolution to the Fermi paradox
• SETI in 2021
• Stellar encounters in the solar neighbourhood and the special case of GJ~710