In 2009, astronomers discovered an exoplanet, identified as Gilese 581b, that possessed the right conditions to harbor liquid water on its surface. The exoplanet is described as a “super-Earth”, as it is seven times larger. However, in 2014, after conducting further research, astronomers reneged on their thoughts about the validity of their initial findings. They thought the Earth-like exoplanet many not even exist at all, having been a mistaken indication from the stars.
Even though over 2,000 extrasolar worlds have been located and observed, the search for an Earth-like planet beyond the Solar System is still in its beginning stages. Astronomers claim the signals that originally provoked the notions of a new exoplanet may been background noise from the cosmos. Due to this reason, astronomers who first found Gilese 581b, by using a spectrograph, among other techniques, dismissed its existence as being a small change in wavelengths of light from a red dwarf star nearby. This star is orbited by Gilese 581d, one of four additional exoplanets thought to exist in the system.
Since then, astronomers have been revisiting the former potential home away from home, and have unearthed some astonishing findings. In a new study, conducted by Mikko Tuomi and Guillem Anglada-Escudé from the Center for Astrophysics Research at the University of Hertfordshire, researchers found that the techniques used to demote Gilese 581b from its super-Earth status were wrongfully applied. The calculations used did not pertain to an exoplanet of this size and mass.
Gilese 581b is located in the acknowledged “Goldilocks zone”, the area in a star system in which liquid water is able to exist. Moreover, the exoplanet has a mass of seven Earths, resulting in a surface gravity that is twice as forceful of that on Earth. To put this into perspective, someone weighing 200 pounds on Earth would experience the relative weight of someone who is 400 pounds.
Although the methods used to discount the existence of the exoplanet have been applied to larger alien worlds, the effect on the host star was significant enough to discount errors in the statistical results. Therefore, it was improbable that the most minuscule planetary signals would have been found, having been perturbed by the noise caused by background radiation and stellar variations.
The researchers stated their use of periodograms of data findings were incompatible, thus inadequate for identifying an exoplanet like Gilese 581b. Periodograms are used to calculate the intensity of varying frequencies from stellar bodies over time that identify integral periodic signals, such as orbits of planets around stars. Considering this claim questions the viability of the original techniques of detecting exo-Earths, the researchers are encouraging astronomers to revisit data collected from periodograms and spectrographs to determine if a potential Earth has been missed. As stated in the study published in the latest issue of the journal Science, the team is confident that Gilese 581b has a signal that equates to that of an Earth-like exoplanet.
By revisiting the findings that first provoked astronomers to consider Gilese 581b as an Earth-like planet, then discounting it, these new studies can be conducted to find other stellar bodies in the area that may resemble Earth. Therefore, by using these new techniques to differentiate between background noise and radiation, more exoplanets may possibly be found that could potentially be a new Earth.
By Alex Lemieux
Photo by Bill Lile – Flickr License