Kepler-442b: Traversing through a Potentially Habitable Exoplanet
By: Minha Shameer and Harshit Kishor Patil
Introduction
Does life exist on other planets? Are we alone in this universe? These are revolutionary questions and exoplanets uncover the boundless possibilities of worlds beyond our own.
5600 exoplanets have been discovered out of the billions that are believed to exist. The Kepler mission by NASA was specifically designed to survey our region of the Milky Way galaxy to discover hundreds of Earth-size and smaller planets in or near the habitable zone. Consequently, Kepler-442b was discovered in 2015 by the Kepler Space Telescope using the transit method.
Kepler 442b is a super Earth exoplanet with a mass that is 2.36 Earths and radius that is 1.36 times that of the Earth. It takes 112.3 days to complete one orbit of its star. We are 1194 light years away from it meaning even with the Voyager 1 (the fastest spacecraft to ever launch), it would take us approximately 20 million years to reach this planet.
The exoplanet stands out as a compelling one due to its placement in the habitable zone of a stable, long-lived star. In recent years it has become a prime candidate for future research into exoplanetary conditions that could support life.
The physical characteristics, significance and potential habitability of the Kepler-442b remains the focal point of this report.
Methodology
This research report discusses the potential habitability of the exoplanet, Kepler-442b and focuses on the characteristics of the exoplanet. Consequently, the research question was defined as:
“What makes Kepler 442-b a contender for a prospective habitable location and how does it
compare with other known exoplanets?”
The research question further guided the literature review. The conceptual framework given below depicts proved data as the independent variables and factors concerning habitability as dependent variables.
The method of research used in this report was literature reviews. Literature reviews help to interpret existing documents, identify the gaps in existing knowledge and ensure novelty of the work done. In this respect,
The research question sought to explore the relationships between variables and conduct statistical analysis from the data retrieved by NASA's Exoplanet Archive.
The authors had access to observational data from the Transiting Exoplanet Survey Satellite (TESS) along with simulations of the planet from NASA’s website.
The paper "Kepler-442b: Implications for Super-Earth Formation and Habitability" by William J. Borucki in The Astronomical Journal (2019) proved insightful and suggests that the exoplanet formed in a region of its system, that allowed a significant amount of its water to remain, increasing habitability potential.
Although significant research has been conducted on the planet, there are a lot of gaps still present which includes the question of the composition of its atmosphere, presence of a magnetic field and geographical features.
Findings
Atmosphere composition and its ability to support life
As of now, the precise composition of Kepler-442b's atmosphere remains unknown as current observational technologies are not sufficient to measure the atmospheric components of such distant exoplanets. However, scientists predict that if the planet has an atmosphere, the composition would be very similar to that of Earth containing gasses such as nitrogen, oxygen and carbon dioxide. Contradicting this, some scientists believe that the atmosphere of the planet might be similar to that of Venus or Mars which then would make the planet less habitable. Figure below depicts NASA’s illustration of the Kepler-442b.
Proximity to its star, the type of star it orbits and the availability of water
Kepler 442b orbits a K type star namely, Kepler 442. Kepler 442 being a K type main sequence star has a high probability of containing exoplanets that may be habitable as the star is slightly smaller, cooler, and less luminous than our Sun, creating wider habitable zones. The exoplanet orbits its star at a radius of 0.409 Au placing it in the habitable zone of its star also known as the “Goldilocks Zone” where conditions may allow for liquid water to exist on the planet. Figure below shows comparison of the habitable zones of different stars.
The water in its liquid form would most likely be found near the equators and stay frozen especially near the poles during prolonged periods of winter. The actual conditions of water to exist would depend on various factors like atmospheric composition, pressure, and greenhouse effects, which remain unknown at this time again due to our insufficient technologies.
Gravity of the planet and comparison to Earth's gravity.
As discussed earlier, the mass of the planet Kepler-442b is estimated to have a mass about 2.34 times that of Earth which is approximately 14.09*1024 kg and the radius of the planet Kepler 442b is estimated to be 1.36 times that of Earth which is approximately 8664.6km.
Using the formula,
Kepler-442b 's acceleration due to gravity is Approximately 11.1 m/s² which is about 13% stronger than Earth’s. However, it is still quite hospitable.
Presence of a magnetic field and its strength
Magnetic field lines being invisible pose significant challenges in detecting magnetic fields of such distant exoplanets. A magnetic field is necessary to protect the planet from stellar winds (supersonic outflow of matter from the surface layers of a star) and it is unknown whether Kepler 442b has one.
Planet's rotation period and how these factors affect its climate
The rotation period of the planet is unknown; however, this period—how long it takes for the planet to complete one rotation on its axis—would have a significant impact on its climate. The planet might have a possibility of tidal locking (phenomenon where one side of the planet always faces the star while the other side remains in darkness). This could lead to extreme temperature differences between day and night. A thick atmosphere could help redistribute heat from the star-facing side to the night side. This would make the temperature stable and the planet more habitable. Due to a shorter orbital period, the planet might experience frequent seasonal changes if the axial tilt were similar to that of earth. However we can only speculate as the axial tilt of the planet is unknown and hence the nature of seasons isn't confirmed yet.
Vegetation, life forms, or ecosystems present on the planet
No vegetation or lifeform has been discovered in Kepler 442b as we do not have the sufficient technologies required. Spectroscopic studies would have been able to provide heat signatures which detect presence of plant life but due to the extremely long distance these studies are not possible.
Surface composition and unique geological features that could enhance habitability
Kepler 442b is hypothesized to be a rocky planet due to its similarity of size with the Earth. Although not proved, it is likely that the planet may have mountains, volcanoes, valleys and plains. If it has an internal structure similar to that of Earth it may even have volcanic activity. Volcanic activity could contribute to an atmosphere, depending on the internal heat.
Comparison to other known exoplanets
Although Kepler-442b is a good candidate for future studies, there are other exoplanets like the Proxima Centauri B which are much closer to Earth standing at 4.24 light years, that stand as a better priority for scientists today. Kepler-442b being 1194 light years away pose a lot of challenges. Figure shows comparison of sizes of different Kepler planets discovered through the years.
Potential challenges to habitability
As discussed earlier, the exoplanet is so far away that we lack the technology, as of now, to fill in the blank spaces. If the planet happens to be tidally locked, extreme weather conditions could create inhabitable environments on night and day sides. Moreover, if the planet lacks its own magnetics field, radiation from its star could severely harm any potential life forms. The atmospheric composition is another major factor which has a significant effect on its potential habitability.
Conclusion
Kepler-442b is truly a beautiful planet and has great potential for habitability. It is a compelling case due to its position in the habitable zone of a K type star. The lack of information regarding its composition and magnetic field, largely due to its large distance, remains an issue.
This case sheds light on the need for more advanced equipment and technique that can detect biosignatures and advanced instruments that can directly detect magnetic fields of exoplanets. Future studies should also focus on understanding the core composition and influence of any moons on the planet.
Ongoing and future astronomical missions should aim to provide more detailed information about this ever expanding and fascinating universe. It is when we look at the universe that we truly realize how unique our Earth truly is. Billions of planets exist in the world, yet it is only in Earth, where we find all the elements necessary for our survival.