The superearths are perfect for follow-up research in which scientists – in search of traces of life – search their atmospheres.

The star Gliese 887 is just 11 light-years away from Earth. And around that star, researchers have discovered two superearths: Gliese 887b and Gliese 887c.

Rocky and livable
The planets are larger than Earth and most likely rocky. The planets also appear to be in the habitable zone. This is a zone around the star in which the temperature is high enough to prevent any liquid water from freezing on the superearths surface, but not so high that the water evaporates. In other words, the superearths could harbor liquid water – an important ingredient for life as we know it.

The two planets take just 9.3 and 21.8 days to complete a round around their parent star. And thus they are much closer to their star than the Earth is to the sun. The fact that the two planets are still in the habitable zone is because the star Gliese 887 is much smaller and fainter, so that the habitable zone is closer to the star.

Only good news
The research also shows that the star Gliese 887 has few sunspots and is therefore considerably less active than our own parent star. That is good news. Because if the star were as active as ours, it would likely generate a powerful stellar wind that would severely degrade or even completely destroy the super-Earth’s atmosphere. The fact that the star remains calm also indicates that the superearths still have an atmosphere (possibly even one that is thicker than that of Earth) and can therefore be habitable. In addition, the researchers show that the brightness of Gliese 887 is almost constant. And that makes it much easier to detect and filter out the atmospheres of the superearths. This means that Gliese 887b and -c are ideal for follow-up research using the James Webb space telescope (see box). “These planets are best suited for more detailed research, and the search for life outside our solar system,” said researcher Sandra Jeffers.

Considered the successor to the Hubble space telescope, James Webb is the most powerful space telescope built to date. The telescope is expected to play a major role in the search for life. For example, astronomers can use the telescope to sift through the atmospheres of planets outside our solar system and check whether they contain elements that indicate the presence of life. Unfortunately, it is currently unclear when James Webb will take to the skies. The launch has been postponed many times. It was hoped that the launch would be possible sometime in the spring of 2021. But partly due to the coronavirus – which means that work on the telescope came to rest – postponement seems inevitable again. However, NASA hopes that the telescope – which has already cost about $ 9.7 billion and is 95 percent more expensive than budgeted – can still be launched sometime in 2021.–

Jeffers and colleagues discovered the two superearths by long-term monitoring of the star Gliese 887. They specifically looked for small wobbling movements of the star that indicate that planets are pulling at the star with their gravity. Similarly, within the same research project, called Red Dots, there was also previously a planet around the nearest star Proxima Centauri discovered. And also the candidate planet Star of Barnard b – just 6 light-years away from Earth – was discovered within the Red Dots project and betrayed by its star’s wobbling motion.