Using data collected by the Kepler Space Telescope alongside a number of Earth-bound observatories, an international team of astronomers has confirmed the existence of over a hundred previously unknown exoplanets discovered in the direction of the Aquarius constellation. Among the throng of newly discovered worlds, two potentially habitable exoplanets have been identified orbiting a distant dwarf star.
The Kepler Space Telescope has been responsible for the confirmed discovery of almost 2,500 exoplanets since its launch from Cape Canaveral in 2009. Kepler's primary mission was terminated when the loss of a second reaction wheel stripped the telescope of its ability to precisely fix its position in space.
However, engineers were able to develop a system for steadying the telescope that made use of the pressure exerted by sunlight to compensate for the damaged reaction wheel, allowing it to once again carry out its purpose.
Having been saved from an early retirement, the resurrected Kepler began its K2 mission in June 2014. K2 has been responsible for the discovery of hundreds more exoplanets that have revolutionized our understanding of distant solar systems and how they came to form.
The initial discovery of the most recent batch of exoplanets was made by Kepler as it patiently watched for the periodic dimming in the light signature of one of the many M dwarf (also known as red dwarf) stars that fell under its gaze known as K2-72. This dimming is created as an exoplanet passes across a star's surface, blocking a portion of its light.
Follow-up observations were then carried out by numerous terrestrial telescopes, which captured high-resolution data and spectrographic readings on the planets, allowing the team to confirm 104 exoplanets out of a possible 197 candidate bodies.
All of the exoplanets discovered in the effort are estimated to be around 20 to 50 percent larger than our planet by diameter. The vast majority of the worlds were deemed to be too hostile for the creation and evolution of life. However, astronomers did identify four rocky planets orbiting K2-72, two of which may posses the vital characteristics for harboring life.
K2-72 is situated roughly 181 light years from Earth in roughly the same region as the constellation Aquarius. Two of the rocky planets in orbit around the star are considered to be too hot to be viable candidates for the development of extraterrestrial life. However, the two remaining worlds are thought to orbit within the red dwarf's habitable zone.
On average, red dwarfs such as K2-72 are significantly dimmer, and less than half of the diameter of our own Sun. Because of this, their habitable zone — the region in which a planet can orbit its star and maintain liquid water on its surface — occupies an area much closer to a red dwarf's surface.
K2-72c, which is thought to be the innermost of the two potentially habitable planets, is estimated to be around 10 percent warmer than Earth, and completes a circuit of its parent star once every 15 Earth days. K2-72e, which is believed to traverse a more distant orbit, is roughly 6 percent colder than our planet, and has a more leisurely 24-day yearly cycle.
According to the team, it is possible for life to arise on rocky planets such as K2-72c and K2-72e even though they orbit a cool red dwarf star. A recent discovery suggests that tidally locked exoplanets, which make up the majority of the worlds detected in orbit around red dwarfs, could be rendered habitable by a form of atmospheric climate control process. This revelation paired with the prevalence of red dwarf stars will make them an attractive target for the next generation of terrestrial and spacebound telescopes.