An article published in “The Astrophysical Journal Supplement Series” reports the identification of five new exoplanets, the detection of eight exoplanet candidates that will be verified, and the confirmation of three exoplanets previously detected but not yet confirmed. A team of astronomers led by Fabo Feng and Paul Butler of the Carnegie Institution for Science selected and reanalyzed data gathered in the survey conducted with the UVES instrument mounted on ESO’s VLT using other verification instruments. Two of the new exoplanets are super-Earths in their system’s habitable zone, the first of this type that orbit around red dwarfs not tidally locked,, a positive factor because having always day on one face and always night on the other generates extreme temperatures that lower the chances of life being born.
The survey conducted with the UVES )Ultraviolet and Visual Echelle Spectrograph) instrument mounted on the VLT (Very Large Telescope) was conducted between 2000 and 2007 for a data release in 2009. Since then a lot of progress was made in the search for exoplanets with other instruments, but archive data can be useful even after several years to be re-examined with new algorithms or to examine data about possible exoplanets with other instruments. In this case, the data for 33 red dwarfs were reviewed and the researchers used three other instruments to improve their accuracy: the Carnegie PFS (Planet Finder Spectrograph) at the Las Campanas Observatory, HARPS (High Accuracy Radial velocity Planet Searcher) at ESO’s La Silla Observatory and HIRES (High Resolution Echelle Spectrometer) at the Keck Observatory. Paul Butler explained that combining data from multiple telescopes increases the number of observations and their time baseline and minimizes instrumental bias.
Nearly 40 light years from Earth, GJ180d is one of the identified super-Earths, with an estimated mass of about 7.5 times the Earth’s and a year lasting about 106 Earth days. It has a big mass but is in its system’s habitable zone and is far enough away from its star not to be tidally locked. It’s the closest super-Earth not tidally locked to its star, a factor that increases its habitability potential because each area on its surface has an alternation of day and night. This means that if it has an atmosphere there are no extremes of heat and cold at the levels of the planets on which it’s always day on one face and always night on the other.
About 19 light years from Earth, GJ229Ac is the other identified super-Earth, with an estimated mass of 7.9 times the Earth’s and a year lasting about 122 Earth days. Its system is interesting because the star, with mass and size slightly higher than half the Sun’s, has a brown dwarf as a companion, GJ 229B, one of the first brown dwarfs confirmed in 1995. The interest is due to the fact that a system that from an astronomical point of view is in the neighborhood offers the possibility to study the processes of planetary formation and evolution in binary systems with a brown dwarf.
This research also offers confirmation of the existence of GJ 433 c, a very cold super-Neptune in a system almost 30 light years from Earth. Its first traces were discovered several years ago but there were doubts about its existence. It may be the first candidate of this type to be directly photographed.
The new analysis offered interesting results and will allow follow-up studies. It confirms that red dwarfs can be interesting targets for the search for exoplanets, although doubts remain due to the fact that they’re small but often very active stars with powerful flares. In the future we can expect new information on the confirmed exoplanets and the candidates.
