Astronomers from the Institute of Astrophysics of the Canary Islands have discovered a new super-Earth about 32 light-years from the Solar System. The exoplanet is orbiting a bright red dwarf star, GJ 536, and it’s estimated to have a mass of 5.4 Earths and an orbital period of just under nine days.
The planet, which is called GJ 536 b, is unlikely to be habitable, but the astronomers are interested in finding potential other worlds in the system that might be more life-friendly. This discovery was accepted for publication in Astronomy & Astrophysics.
"So far, the only planet we have found is GJ 536 b, but we are continuing to monitor the star to see if we can find other companions," said lead author Alejandro Suárez Mascareño, in a statement. "Rocky planets are usually found in groups, especially around stars of this type, and we are pretty sure that we can find other low-mass planets in orbits further from the star, with periods from 100 days up to a few years. We are preparing a programme of monitoring for transits of this new exoplanet to determine its radius and mean density."
The astronomers hope to discover a system similar to Trappist 1, which is a red dwarf with three rocky planets in the habitable zone around it. GJ 538 b is not in the habitable zone, but its potential companion might be. The star also has a similar magnetic cycle as the Sun, although on a much shorter period – three years instead of 11. All these characteristics make GJ 538 b a very attractive object.
"This rocky exoplanet is orbiting a star much smaller and cooler than the sun," said co-author Jonay Isaí González. "But it is sufficiently nearby and bright. It is also observable from both the northern and southern hemispheres, which is very interesting for future high-stability spectrographs, and in particular, for the possible detection of another rocky planet in the habitability zone of the star."
The observations were a cooperative effort by many different observatories. The planet was detected using the radial velocity method, which looks at the star’s wobble to work out if a nearby planet is tugging at it.
"To detect the planet, we had to measure the velocity of the star with an accuracy of the order of a meter per second," added co-author Rafael Rebolo. "With the construction of the new instrument ESPRESSO, co-directed by the IAC, we will improve this accuracy by a factor of 10, and will be able to extend our search to planets with conditions very similar to Earth, around this and many other nearby stars."