A paper that will soon appear in the Monthly Notices of the Royal Astronomical Society theorizes that the search for extraterrestrial life might stand a better chance of success if telescopes focus on planets orbiting any of the 500 closest white dwarf stars. These dying stars are about the size of Earth and dimmer than our Sun, so spotting any planets will be a challenge, but researcher Dan Maoz says that NASA’s James Webb Space Telescope (JWST) should be ideal for the job when it launches at the end of this decade.
What’s the Big Idea?
Planets are spotted when they cross between the observing telescope and the star it orbits. When a planet crosses a white dwarf, the light from the star illuminates any atmosphere present and leaves a chemical signal. If the planet, like the star, is approximately Earth-sized, the signal is especially obvious. Maoz and colleague Avi Loeb demonstrated that in such cases a telescope like JWST should be able to spot both oxygen and water vapor after only a few hours of observation. The discovery of oxygen is of particular interest to astronomers because it’s regularly replenished in the atmosphere through plant photosynthesis.