Title: NASA’s Kepler Space Telescope Solves the Mystery of ‘Missing’ Exoplanets
NASA’s retired Kepler Space Telescope was crucial in uncovering a newfound understanding of the “missing” exoplanets between super-Earths and sub-Neptunes, according to a recent study. Scientists have long pondered the disparity in the number of exoplanets within the size range of 1.5 to 2 times the size of Earth; however, new evidence suggests that these missing planets may not be missing at all.
Observations made using the Kepler Space Telescope have allowed scientists to witness certain exoplanets losing their atmospheres and gradually shrinking. Researchers now believe that the shrinking is attributed to the planets’ cores pushing their atmospheres away, from the inside out.
The recent findings support the theory that the “size gap” of exoplanets can be explained by sub-Neptunes losing their atmospheres over time if their mass is insufficient to retain them. Consequently, these planets shrink and assume the appearance of super-Earths, creating a noticeable gap between the two size categories.
Two mechanisms have been proposed to explain this atmospheric loss: core-powered mass loss and photoevaporation. However, the study using data from NASA’s K2 mission argues in favor of the core-powered mass loss mechanism.
Core-powered mass loss occurs when radiation emitted from a planet’s hot core gradually pushes its atmosphere away over an extended period. On the other hand, photoevaporation transpires when the high-energy radiation from the planet’s host star strips off its atmosphere.
To investigate further, the research team examined star clusters Praesepe and Hyades, both estimated to be 600 to 800 million years old, utilizing data from NASA’s K2 mission. Strikingly, they discovered that nearly 100% of stars in these clusters have sub-Neptune planets or planet candidates in their orbit, indicating a lack of photoevaporation in these systems.
As a result, the team deduced that core-powered mass loss is the primary explanation for the gradual atmospheric loss experienced by less massive sub-Neptunes.
While this study has shed light on the missing exoplanets, scientists emphasize that research is ongoing, and further investigations will be conducted to refine our understanding of these mechanisms.
The NASA Exoplanet Archive, operated by Caltech in Pasadena under contract with NASA, provided vital data for this study. The Kepler Space Telescope, which successfully discovered more than 2,600 confirmed planets and thousands of additional candidates during its nine-year mission, continues to leave an indelible mark on our understanding of the universe, even after running out of fuel in 2018.
In conclusion, the Kepler Space Telescope has been instrumental in cracking the enigma of the “missing” exoplanets, unveiling the mechanisms of core-powered mass loss and photoevaporation. This discovery paves the way for a deeper comprehension of the universe and inspires further investigations into the mysteries of the cosmos.