Lazarus Stars: Modeling and searching for engineered stars

The aging and gradual brightening of the Sun will challenge Earth’s habitability in the next few
billion years. If life exists elsewhere in the Universe, the aging of its host star similarly poses
an existential threat. One solution, which we dub a Lazarus star, is for an advanced civilization
to remove (or star-lift) mass from their host star at a rate that offsets the increase in luminosity,
keeping the flux on the habitable planet(s) constant and extending the lifetime of their star.
While this idea has existed since 1985 when it was first proposed by Criswell, numerical
investigations of star-lifting have been lacking. Here, we use the stellar evolution code MESA
to find mass vs. age and ¤𝑀 vs. age relations which would hold the flux on surrounding planets
constant. We explore initial mass ranging from 0.2 M⊙ to 1.2 M⊙ . For most stars with a mass
initially below about 0.4M⊙ , we find that star-lifting increases their main-sequence lifetimes
up to 500 Gyr until they approach the hydrogen burning limit and star-lifting is no longer
possible. For more massive stars, star-lifting increases main-sequence lifetimes by 1 Gyr to
100 Gyr, though they still enter the red-giant phase. For example, a Sun-like star has a main-
sequence lifetime which can be increased by up to 3 Gyr. This requires a mass-loss rate of
about 0.05 MCeres per year. We compare star-lifting to other survival strategies and briefly
discuss methods for detecting these engineered stars