Hottest planet in the solar system
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The Hottest Planet in the Solar System
Introduction to Planetary Temperatures
Understanding the temperatures of planets within our solar system and beyond is crucial for comprehending their atmospheric dynamics and potential for hosting life. Among the planets, some exhibit extreme temperatures due to their proximity to their parent stars and unique atmospheric compositions.
Hottest Planet in the Solar System: Venus
While the search for the hottest planet often leads to discussions about exoplanets, within our solar system, Venus holds the title. Despite being second from the Sun, Venus experiences surface temperatures around 735 K (462 °C), hotter than Mercury, the closest planet to the Sun. This extreme heat is primarily due to a runaway greenhouse effect caused by its thick atmosphere rich in carbon dioxide.
Exoplanets: Extreme Temperatures Beyond the Solar System
Ultra-Hot Jupiters
Exoplanets, particularly ultra-hot Jupiters, exhibit some of the highest temperatures recorded. These gas giants orbit very close to their parent stars, leading to extreme irradiation and high atmospheric temperatures. For instance, KELT-9b, an ultra-hot Jupiter, has a dayside temperature exceeding 4500 K, making it the hottest known planet to date7 9. This temperature is comparable to that of a mid-K-type star, highlighting the extreme conditions these planets endure.
Thermal Emission and Atmospheric Properties
The study of thermal emissions from these planets provides insights into their atmospheric properties. For example, HD 149026b has a brightness temperature of 2300 K at 8 µm, which is significantly higher than predicted by uniform blackbody models, suggesting unique atmospheric characteristics1. Similarly, TOI-1431b/MASCARA-5b exhibits a dayside temperature of 2983 K, with efficient heat transport between its dayside and nightside hemispheres6.
Transition Between Hot and Ultra-Hot Jupiters
Research indicates a transition in atmospheric properties between hot and ultra-hot Jupiters. This transition is marked by changes in thermal profiles, with hotter exoplanets showing stronger thermal inversions due to the presence of atomic metals and molecular dissociation4 5. These findings are supported by secondary eclipse observations and theoretical models, which reveal that ultra-hot Jupiters have even hotter daysides compared to their cooler counterparts.
Conclusion
In summary, while Venus is the hottest planet within our solar system, exoplanets such as KELT-9b and HD 149026b exhibit even more extreme temperatures. The study of these ultra-hot Jupiters not only expands our understanding of planetary atmospheres but also challenges our models of atmospheric dynamics under extreme conditions. These findings underscore the diversity and complexity of planetary systems beyond our own.
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The hottest planet
The smallest known transiting planet, HD 149026b, has a brightness temperature of 2,300 200 K at 8 m, making it the hottest known extrasolar planet.
Highly CitedDiscovery of a hot, transiting, Earth-sized planet and a second temperate, non-transiting planet around the M4 dwarf GJ 3473 (TOI-488)
GJ 3473 b, a hot Earth-sized planet orbiting an M4 dwarf star, is one of the hottest transiting Earth-sized planets known, making it a potential target for thermal emission spectroscopy.
Validation of 13 Hot and Potentially Terrestrial TESS Planets
13 potentially terrestrial TESS planets have been validated, including seven ultra-short-period planets, and could be probed by the James Webb Space Telescope.
A transition between the hot and the ultra-hot Jupiter atmospheres
A transition in near-infrared atmospheric emission occurs between hot and ultra-hot Jupiters, with ultra-hot Jupiters having even hotter daysides at 4.5 m compared to 3.6 m.
Extremely Irradiated Hot Jupiters: Non-oxide Inversions, H− Opacity, and Thermal Dissociation of Molecules
Extremely irradiated hot Jupiters exhibit strong thermal inversions without the need for TiO or VO, and molecular species like H2O, TiO, and VO are thermally dissociated at pressures probed by transit and eclipse observations.
Highly CitedTOI-1431b/MASCARA-5b: An Ultra-hot Jupiter Orbiting One of the Hottest & Brightest Known Exoplanet Host Stars
TOI-1431b/MASCARA-5b is an ultra-hot Jupiter orbiting one of the hottest and brightest known exoplanet host stars, with its nightside temperature being the second hottest ever measured.
The stable climate of KELT-9b
KELT-9b, the hottest planet discovered, has a stable climate with a day-night heat redistribution efficiency of $sim$0.3 and a Bond albedo consistent with zero, despite its extreme irradiation levels.
ATMOSPHERIC CHARACTERIZATION OF THE HOT JUPITER KEPLER-13Ab
The hot Jupiter Kepler-13Ab has a day-side hemisphere temperature of 2750 160 K, an atmospheric temperature inversion, and a relatively high geometric albedo, suggesting a high atmospheric mass and radius.
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