A super-earth with a size of only 5 earth masses
Red dwarfs have proven to be a treasure trove for exoplanet hunters in recent years. In addition to a few exoplanet candidates found around the TRAPPIST-1 stars, Glise 581, Glise 667C and Kepler 296, do not forget the recent discovery by the European Southern Observatory of the planet in orbit within the zone of habitation of the nearest neighbor of our Sun, Proxima Centauri.
And it seems, this trend will continue, judging by the latest discovery by a team of European scientists. Using data from the HARPS tools and the HARPS-N of the European Southern Observatory, they found a candidate for exoplanets in orbit around the GJ 536 red M-class dwarf located at 32.7 light years (10.03 parsec) from the Earth.
According to their study "Super Earth in the orbit of an adjacent M-dwarf GJ 536", this planet is a super-earth - a class of exoplanets, whose mass is from 1 to 15 Earth masses. In this case, the planet can boast at least 5.36 ± 0.69 Earth masses, has an orbital period of 8.7076 ± 0.0025 days and an orbit radius around its parent star of 0.066661 astronomical units.
The team was led by Dr. Alejandro Suárez Mascarenjo from the Canary Institute of Astrophysics (IAC). The discovery of the planet was part of his thesis work, which was conducted under the guidance of Dr. Raphael Rebolo (professor at the University of LA-Laguna, member of the Higher Council for Scientific Research of Spain and the Canary Institute of Astrophysics). And although this planet is not a potentially habitable world, it provides interesting opportunities for exploring the planets.
The sky survey in which this planet was discovered was part of a joint effort between the IAC (Spain) and the Geneva Observatory (Switzerland). The data came from the HARPS and HARPS-N instruments, which are mounted on a 3.6-meter telescope at the La Silva Observatory in Chile and the 3,6-meter La Palma telescope in Spain. They are combined with photometric data from the sky review of the All Sky Automated Survey (ASAS) in Chile and Maui.
The research team relied on the measurement of the radial velocity of the star to distinguish the presence of the planet, as well as data on the spectrographic observations of the star in 8.6 years. With all this, they not only discovered a candidate in exoplanets with a mass of 5 terrestrial masses, but also derived information about the star itself, which showed that the star has a period of revolution of about 44 days and a magnetic cycle lasting more than 3 years.
For comparison, our Sun has a period of rotation around its axis of 25 days and a magnetic cycle of about 11 years, which are characterized by changes in the levels of solar radiation emitted by it, coronal mass ejections and the appearance of sunspots. In addition, a recent study by the Harvard-Smithsonian Institute of Astrophysics has shown that Proxima Centauri has a 7-year star-shaped magnetic cycle.
This discovery is only the last in a long series of discoveries of exoplanets near red dwarfs of M-class with low mass, low luminosity. And looking ahead, the team hopes to continue studying the GJ 536 to see if it has a planetary system in which there could be a land-like planet or several gas giants.
"So far we've only discovered one planet, but we plan to continue monitoring the star to find other companions in large orbits," said Dr. Mascarenjo. "According to our estimates, there is still a place for other planets with low mass or even with a mass of Neptune in orbit from hundreds of days to several years."