brown dwarfs, life on

The possibility that low-mass brown dwarfs might contain liquid water suggests that they might also be capable of supporting some kind of life, an idea first put forward by Harlow Shapley.1 Conceivably, organisms might evolve to be able to exploit the deep infrared radiation given off by such an object, both for photosynthesis and perception, the latter through eyes equipped for infrared vision or thermal sensors like those of snakes. Wrote Shapley:


The imagination boggles at the possibilities of self-heating planets that do not depend, as we do, on the inefficient process of getting our warmth through radiation from a hot source, the sun, millions of miles away. What a strange biology might develop in the absence of the violet-to-red radiation!


One problem would be the high gravity – 100 times stronger than on Earth. However, considering the ability of ants, for example, to lift around 160 times their own body weight, it is not out of the question that life could evolve under gravitationally extreme conditions (see gravitational life). Other obstacles to life on brown dwarfs would include the lack of available surfaces for chemical reactions, suitable temperatures, and the relative lack of heavy elements such as potassium, calcium, and iron, which are necessary for living processes with which we are familiar.


A more conventional possibility would be life on planets that are orbiting brown dwarfs. Andryeschchev and Scalo, for example, modeled habitable distances and time scales for such planets.2



1. Shapley, H. "Crusted Stars and Self-Heating Planets," Matemática y Teorética, Serie A (Tucumán National University, Argentina), 14 (1962).
2. Andreyeschchev, A. and Scalo, J. "Duration and Habitability of Brown Dwarf Planets." Bioastronomy 2002: Great Barrier Reef Conference Proceedings(2002).