The article mentions the star being an ultra-cool dwarf star, but doesn't give an explanation of what that means. Here's some info from Wikipedia that I found u

The article mentions the star being an ultra-cool dwarf star, but doesn't give an explanation of what that means. Here's some info from Wikipedia that I found useful: TRAPPIST-1 is an ultracool dwarf star that is approximately 8% the mass of and 11% the radius of the Sun. It has a temperature of 2550 K and is at least 500 million years old. In comparison, the Sun is about 4.6 billion years old and has a temperature of 5778 K. Due to its mass, the star has the ability to live for up to 4–5 trillion years ... https://en.wikipedia.org/wiki/TRAPPIST-1 https://en.wikipedia.org/wiki/TRAPPIST-1