About 11 years away from Earth, a system of hot, rocky exoplanets rotates around a small, red dwarf star that is abnormally quiet. The fact that these two objects are so close makes them relatively easy to analyze, and a potential third planet in the star’s habitable zone makes the structure a rather interesting one.
GJ 887 is a red dwarf star with a size similar to that of the Sun. Sandra Jeffers from the University of Göttingen in Germany and her colleagues discovered its planets using the High Accuracy Radial Velocity Planet Searcher (HARPS) located at La Silla Observatory in Chile.
They spotted the system by looking for wobbles in the star’s light caused by the planets’ gravitational pull. The team observed wobbles with three different patterns: one suggested a planet that orbited the star every 9.3 days, another indicated to a planet that rotated every 21.8 days, and the third pointed to a world that circled about every 50 days. Both the inner planets are closer to the star than Mercury is to our Sun.
It’s an Existential Matter
The two closer planets are way too hot to host life, as their average temperatures were registered to 195°C (32° Fahrenheit) and 79°C (174° Fahrenheit) for the distant one. The third planet, if it actually exists, could be located within the star’s habitable zone, which is the area where water on the surface of a planet could be liquid rather than freezing or boiling.
However, there’s an issue regarding the planet’s existence. The team observed GJ 887 for 80 nights, so there was no time to look for more than one orbit of this probable planet. There is a possibility that the apparent 50-day wobble could be generated by the star itself, so the researchers are analyzing more data to try to confirm the third planet’s existence, Jeffer explains.
“GJ 887 is one of the most inactive stars we’ve ever seen,” says Jeffers. “It’s the best star close to the Sun to understand whether its exoplanets have atmospheres and to characterize those atmospheres, and to understand whether those planets have life. We’ll be able to look at these planets’ atmospheres with the James Webb Space Telescope, which is slated to launch in 2021.”