The Discovery and Characteristics of Exoplanet K2-90 c: A Super Earth
The search for exoplanets—planets that orbit stars beyond our solar system—has captivated astronomers for decades. Among the many discoveries made over the years, the discovery of exoplanet K2-90 c has been a noteworthy addition to our growing understanding of distant planetary systems. K2-90 c is a Super Earth, an exoplanet that is larger than Earth but smaller than the gas giants like Uranus and Neptune. It was discovered in 2016 through the powerful data-gathering capabilities of the Kepler Space Telescope during its K2 mission. This discovery provides valuable insights into the nature of exoplanets within distant star systems, shedding light on their potential habitability and the various factors that govern their physical and orbital characteristics.
The K2 Mission and the Discovery of K2-90 c
Launched in 2009, NASA’s Kepler Space Telescope was designed specifically to detect Earth-like exoplanets using a method called the transit method. This technique involves observing the dimming of a star’s light as a planet passes, or transits, in front of it from the telescope’s point of view. The K2 mission, which began in 2014, was a continuation of Kepler’s original mission and focused on a broader range of stars, including those in more distant and varied regions of space.
In 2016, one of the exciting discoveries made by the Kepler Space Telescope during the K2 mission was K2-90 c. The planet was identified as part of the K2-90 system, located approximately 438 light-years away from Earth. This discovery was part of a larger effort to catalog and study exoplanets in the Milky Way galaxy, using the detailed photometric data gathered by Kepler’s sensors. The discovery of K2-90 c, as well as the other planets in the K2-90 system, provided a critical dataset for astronomers studying the formation and characteristics of Super Earths.
Characteristics of K2-90 c
K2-90 c is classified as a Super Earth, a type of exoplanet that is larger than Earth but smaller than the gas giants in our solar system. It has several key physical and orbital characteristics that make it an intriguing object of study. These characteristics include its mass, radius, orbital parameters, and its eccentric orbit, all of which contribute to the understanding of how such planets form and behave in distant star systems.
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Mass and Radius:
K2-90 c has a mass that is about 2.24 times that of Earth, which places it firmly in the Super Earth category. Super Earths are typically defined as planets with a mass between 1.5 and 10 times that of Earth. The planet also has a radius that is 1.3 times the radius of Earth. This combination of mass and radius indicates that K2-90 c could have a rocky or potentially icy composition, with a thick atmosphere or possibly even an oceanic surface, depending on its environmental conditions. The exact composition of the planet is still under investigation, but these measurements suggest that K2-90 c could be a solid, rocky planet with characteristics similar to Earth, but potentially with a much different atmosphere and surface conditions. -
Orbital Radius and Period:
K2-90 c orbits its host star at a very close distance of only 0.035 astronomical units (AU), which is much smaller than Earth’s distance from the Sun (1 AU). This places K2-90 c in the category of “hot” planets, as it is located very close to its star and likely experiences extreme temperatures on its surface. The orbital period of K2-90 c, or the time it takes to complete one orbit around its star, is remarkably short: just 0.0079 days, or about 11.4 hours. Such a quick orbit means that K2-90 c is subject to intense stellar radiation and likely experiences significant tidal forces due to its proximity to the star. -
Eccentricity:
The orbit of K2-90 c is slightly elliptical, with an eccentricity of 0.19. Eccentricity measures how much an orbit deviates from being a perfect circle, with values ranging from 0 (a perfect circle) to 1 (an elongated ellipse). A moderately eccentric orbit like K2-90 c’s suggests that the planet’s distance from its star varies throughout its orbit. This could lead to varying climatic conditions on the planet, with potential changes in temperature and atmospheric pressure during different phases of its orbit. Such characteristics are important when considering the potential habitability of exoplanets, as variations in climate could impact the planet’s ability to support life, if any exists.
The Star System: K2-90
K2-90 c resides in the K2-90 system, which is located about 438 light-years from Earth in the constellation of Leo. The host star of K2-90 c is a relatively faint star with a stellar magnitude of 13.707, meaning it is not visible to the naked eye and can only be detected with telescopes. Despite its faintness, the K2-90 system has garnered significant interest from astronomers due to the presence of K2-90 c and the other planets in the system. The system is likely to be composed of several planets, each with its own unique characteristics.
The discovery of K2-90 c within this system provides valuable insights into the diversity of exoplanet types and the conditions that prevail in distant star systems. As one of the Super Earths identified in the K2 mission, K2-90 c represents a type of planet that could potentially offer clues about the processes that lead to planet formation in our galaxy. Studies of such exoplanets may help scientists understand how planetary systems evolve and how planets of varying sizes and compositions can exist in close proximity to their stars.
Detection Method: Transit
The primary method used to detect exoplanets like K2-90 c is the transit method, which involves observing the dimming of a star’s light as a planet passes in front of it. This method relies on the fact that the planet blocks a small portion of the star’s light during its orbit, causing a slight but measurable dip in the star’s brightness. By carefully monitoring these dips, astronomers can infer the presence of an exoplanet and calculate its size, orbital period, and other important parameters.
The transit method has been highly successful in detecting exoplanets, particularly those that are located in or near the so-called “habitable zone” of their star—where conditions might be right for liquid water to exist. While K2-90 c orbits far too close to its star to be within a habitable zone, the method is still valuable for discovering planets that may hold clues to the potential for life elsewhere in the universe. The data gathered from such transits can also be used to study the atmospheres and compositions of exoplanets, providing further insights into their suitability for hosting life.
Future Studies and the Potential for Habitability
Although K2-90 c is unlikely to be within the habitable zone of its star due to its proximity, the study of such planets is crucial for understanding the potential for life on other planets. Super Earths like K2-90 c could have characteristics that make them suitable for life, albeit with a very different environment compared to Earth. Future missions, such as those involving the James Webb Space Telescope (JWST) or the upcoming Nancy Grace Roman Space Telescope, may provide more detailed observations of planets like K2-90 c, enabling scientists to study their atmospheres, weather patterns, and possible signs of habitability in greater detail.
Additionally, the study of K2-90 c’s eccentric orbit and its relationship with its host star can provide important clues about the conditions under which planets form and evolve. These insights could help refine models of planetary system formation and guide the search for exoplanets that might be more similar to Earth, with more favorable conditions for life.
Conclusion
The discovery of K2-90 c, a Super Earth located 438 light-years from Earth, represents an exciting advancement in our understanding of exoplanets. This planet, with its mass of 2.24 times that of Earth and radius 1.3 times greater than Earth’s, offers scientists a unique opportunity to study planets that are larger than Earth but smaller than the gas giants. With its close orbit to its star and eccentric orbital path, K2-90 c may not be a candidate for habitability, but it contributes to our understanding of planetary systems and their diverse characteristics.
As astronomers continue to explore distant stars and their planetary systems, the study of planets like K2-90 c will help answer fundamental questions about the formation of planets and the potential for life elsewhere in the universe. The ongoing exploration of such exoplanets is crucial for advancing our knowledge of the cosmos and deepening our understanding of the forces that shape the worlds beyond our own solar system.