What is the cold planet
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Understanding Cold Planets: Characteristics and Discoveries
Earth's Cold Environments
Cold Biosphere on Earth
Earth is often considered a cold planet due to the extensive presence of low-temperature environments. Over 80% of Earth's biosphere exists at temperatures of 5°C or lower, with 10-20% of its surface remaining frozen3. These cold environments are home to diverse microbial life forms that have evolved unique adaptations to survive and thrive in such conditions. These adaptations are crucial for the biogeochemical cycles on Earth and provide insights into potential life on other icy planets and moons3.
Permafrost and Ice Ecosystems
Permafrost and ice are significant components of Earth's cryogenic environments. These frozen habitats preserve biological material and genetic information, offering a window into past climatic conditions and potential life forms that could exist on other cryogenic planets4. Studies of Earth's permafrost can help predict the types of ecosystems that might be found on other cold planets, making Earth a valuable model for understanding extraterrestrial cryogenic ecosystems4.
Extraterrestrial Cold Planets
Discovery of Cold Exoplanets
Recent advancements in astronomical techniques, such as gravitational microlensing, have led to the discovery of several cold exoplanets. For instance, the cold planet KMT-2019-BLG-0842Lb has a mass ratio similar to that of Uranus in our solar system, indicating a very low planet/host mass ratio2. Another example is the cold Neptune-mass planet OGLE-2007-BLG-368Lb, which was discovered through microlensing and adds to the growing list of cold Neptune-mass planets6.
Characteristics of Cold Exoplanets
Cold exoplanets often have masses and orbital distances that suggest they are "failed" gas giants, meaning they did not accumulate enough mass to form substantial gaseous envelopes7. These planets are typically found at distances from their host stars where temperatures are low enough to prevent significant atmospheric formation, resulting in icy or frozen surfaces7.
Cold Neptune and Jupiter Relations
Research indicates that cold Jupiters, which are giant planets with masses greater than 0.3 times that of Jupiter, are more commonly found around stars that also host super Earths9. This suggests a strong correlation between the presence of super Earths and cold Jupiters, implying that these planets share similar formation origins and do not compete for solid material during their formation9.
Potential for Cryovolcanism
Cryovolcanic Activity on Cold Ocean Planets
Some cold exoplanets, referred to as cold ocean planets, may have subsurface oceans beneath their icy surfaces. These planets could experience significant internal heating from tidal and radiogenic sources, leading to geological activities such as cryovolcanism10. Planets like Proxima Cen b and LHS 1140 b are considered prime candidates for such activity due to their thin ice shells and high internal heating rates10. Cryovolcanism on these planets could potentially release water and other materials from their subsurface oceans into space, making them astrobiologically significant and worthy of further study10.
Conclusion
Cold planets, both within our solar system and beyond, present unique environments that challenge our understanding of planetary science and astrobiology. Earth's cold biosphere and permafrost provide valuable models for studying potential life on other icy worlds. The discovery of cold exoplanets through techniques like gravitational microlensing has expanded our knowledge of planetary formation and the prevalence of such planets in the galaxy. Additionally, the potential for cryovolcanism on cold ocean planets highlights the dynamic and possibly habitable nature of these distant worlds. As research continues, these cold planets will remain a focal point in the search for extraterrestrial life and the study of planetary ecosystems.
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Most relevant research papers on this topic
Coping with Our Cold Planet
Cold is also prevalent in the atmosphere, with 90% of the Earth's surface experiencing temperatures below 5°C.
Highly CitedKMT-2019-BLG-0842Lb: A Cold Planet below the Uranus/Sun Mass Ratio
A cold planet with a low planet/host mass ratio has been discovered, similar to Uranus/Sun's, and high-resolution images could confirm this hypothesis.
Earth's perennially frozen environments as a model of cryogenic planet ecosystems
Earth's permafrost and ice serve as models for potential ecosystems and life on extraterrestrial cryogenic planets, offering insights into past events and potential life preservation.
SPITZER PARALLAX OF OGLE-2015-BLG-0966: A COLD NEPTUNE IN THE GALACTIC DISK
A cold Neptune has been detected orbiting a M dwarf in the Galactic disk, the second planet detected in the Spitzer Galactic distribution sample.
Highly CitedA COLD NEPTUNE-MASS PLANET OGLE-2007-BLG-368Lb: Cold neptunes are common
Neptune-mass planets are at least three times more common than Jupiters in this region, with a mass ratio function scaling as dNpl/dlog q 0.70.2.
Highly CitedDISCOVERY AND MASS MEASUREMENTS OF A COLD, 10 EARTH MASS PLANET AND ITS HOST STAR
This study discovered and measured the cold, low-mass planet MOA-2009-BLG-266Lb, which may be a "failed" gas giant with a mass similar to Earth's.
Highly CitedThe Super Earth–Cold Jupiter Relations
Cold Jupiters are three times more likely to be found around super Earths than around field stars, suggesting they share similar origins and do not compete for solid material.
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