Ultraviolet Radiation from Low-Mass Stars Could Render Planets Uninhabitable

An artist’s impression of an active red dwarf star irradiating an orbiting planet. Credit: G. Bacon (STScI)/NASA/ESA
Low-mass stars are currently the most promising targets when searching for potentially habitable planets, but new research has revealed that some of these stars produce significant amounts of ultraviolet (UV) radiation throughout their lifetimes. Such radiation could hinder the development of life on any orbiting planets. 

By Amanda Doyle | SPACE.com

M-dwarfs are stars that are cooler and less massive than stars like our Sun, and are the most common type of star in the Galaxy, meaning that it is vital that we better understand them and the influence they have on their planets.

Detecting terrestrial planets in the habitable zone — the region where liquid water can exist on a planet’s surface — when they pass in front of, or transit, Sun-like stars is difficult. This is partly because we only see a small dip in the light as the planet crosses the star, and also partly because their orbits are long enough that we have to wait several years to observe multiple transits. However, because M-dwarfs are smaller and cooler, the planets in their habitable zone are much closer to their star, resulting in larger and more frequent drops in light, making them easier to detect. [How to Tell Star Types Apart (Infographic)]

This makes M-dwarfs ideal candidates when searching for potentially habitable planets, which has led to habitable zone terrestrial planets being discovered around M-dwarfs including Proxima Centauri, TRAPPIST-1 and Ross 128.

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