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Neptunian Desert
The Neptunian Desert or sub-Jovian desert is broadly defined as the region close to a star (period 0.1 ) exoplanets are found. This area receives strong irradiation from the star, meaning the planets do not retain their gaseous atmosphere as they evaporate, leaving just a rocky core. Neptune-sized planets should be easier to find in short-period orbits, and many sufficiently massive planets have been discovered with longer orbits from surveys such as CoRoT and Kepler. The physical mechanisms that result in the observed Neptunian Desert are currently unknown, but have been suggested to be due to a different formation mechanism for short-period super-Earth and Jovian exoplanets, similar to the reasons for the brown dwarf desert. The exoplanet NGTS-4b, with mass of 20 , and a radius 20% smaller than Neptune, was found to still have an atmosphere while orbiting every 1.3 days within the 'Neptunian Desert' of NGTS-4, a K-dwarf star located 922 light-years from Earth. The atmosph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neptunian Desert Visualization
Neptune was discovered in 1846 and has only made occasional appearances in fiction since then. The first time it was mentioned, then called "Leverrier's planet", was in the 1848 novel '' The Triumphs of Woman'' by Charles Rowcroft where an inhabitant of the planet visits Earth. The earliest stories where Neptune itself directly appears as a setting, such as the 1930s works " The Monsters of Neptune" by Henrik Dahl Juve and ''Last and First Men'' by Olaf Stapledon, portray it as a rocky planet rather than as having its actual gaseous composition; in the latter, it becomes humanity's refuge in the far future when the Sun expands. Later works rectified this error, with Alexei Panshin's 1969 short story " One Sunday in Neptune" depicting a voyage into Neptune's atmosphere and Alex Irvine's 2003 story " Shepherded by Galatea" featuring resource extraction in the atmosphere. In the 1969 novel '' Macroscope'' by Piers Anthony, Neptune is converted to a world ship. Neptune's largest mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orbital Period
The orbital period (also revolution period) is the amount of time a given astronomical object takes to complete one orbit around another object. In astronomy, it usually applies to planets or asteroids orbiting the Sun, moons orbiting planets, exoplanets orbiting other stars, or binary stars. For celestial objects in general, the sidereal period ( sidereal year) is referred to by the orbital period, determined by a 360° revolution of one body around its primary, e.g. Earth around the Sun, relative to the fixed stars projected in the sky. Orbital periods can be defined in several ways. The tropical period is more particularly about the position of the parent star. It is the basis for the solar year, and respectively the calendar year. The synodic period incorporates not only the orbital relation to the parent star, but also to other celestial objects, making it not a mere different approach to the orbit of an object around its parent, but a period of orbital relations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neptune
Neptune is the eighth planet from the Sun and the farthest known planet in the Solar System. It is the fourth-largest planet in the Solar System by diameter, the third-most-massive planet, and the densest giant planet. It is 17 times the mass of Earth, and slightly more massive than its near-twin Uranus. Neptune is denser and physically smaller than Uranus because its greater mass causes more gravitational compression of its atmosphere. It is referred to as one of the solar system's two ice giant planets (the other one being Uranus). Being composed primarily of gases and liquids, it has no well-defined "solid surface". The planet orbits the Sun once every 164.8 julian year (astronomy), years at an average distance of . It is named after the Neptune (mythology), Roman god of the sea and has the astronomical symbol , representing Neptune's trident. Neptune is not visible to the unaided eye and is the only planet in the Solar System found by mathematical prediction ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exoplanets
An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not recognized as such. The first confirmation of detection occurred in 1992. A different planet, initially detected in 1988, was confirmed in 2003. There are many methods of detecting exoplanets. Transit photometry and Doppler spectroscopy have found the most, but these methods suffer from a clear observational bias favoring the detection of planets near the star; thus, 85% of the exoplanets detected are inside the tidal locking zone. In several cases, multiple planets have been observed around a star. About 1 in 5 Sun-like starsFor the purpose of this 1 in 5 statistic, "Sun-like" means G-type star. Data for Sun-like stars was not available so this statistic is an extrapolation from data about K-type stars. have an "Earth-sized"For the purpose of this 1 in 5 statistic, Earth-sized means 1–2 Earth radii. planet in the habitable zone. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CoRoT
CoRoT (French: ; English: Convection, Rotation and planetary Transits) was a space telescope mission which operated from 2006 to 2013. The mission's two objectives were to search for extrasolar planets with short orbital periods, particularly those of large terrestrial size, and to perform asteroseismology by measuring solar-like oscillations in stars. The mission was led by the French Space Agency (CNES) in conjunction with the European Space Agency (ESA) and other international partners. Among the notable discoveries was CoRoT-7b, discovered in 2009 which became the first exoplanet shown to have a rock or metal-dominated composition. CoRoT was launched at 14:28:00 UTC on 27 December 2006, atop a Soyuz 2.1b rocket, reporting first light on 18 January 2007. Subsequently, the probe started to collect science data on 2 February 2007. CoRoT was the first spacecraft dedicated to the detection of transiting extrasolar planets, opening the way for more advanced probes such as Ke ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kepler Space Telescope
The Kepler space telescope is a disused space telescope launched by NASA in 2009 to discover Earth-sized planets orbiting other stars. Named after astronomer Johannes Kepler, the spacecraft was launched into an Earth-trailing heliocentric orbit. The principal investigator was William J. Borucki. After nine and a half years of operation, the telescope's reaction control system fuel was depleted, and NASA announced its retirement on October 30, 2018. Designed to survey a portion of Earth's region of the Milky Way to discover Earth-size exoplanets in or near habitable zones and estimate how many of the billions of stars in the Milky Way have such planets, Kepler's sole scientific instrument is a photometer that continually monitored the brightness of approximately 150,000 main sequence stars in a fixed field of view. These data were transmitted to Earth, then analyzed to detect periodic dimming caused by exoplanets that cross in front of their host star. Only planets whose ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Super-Earth
A super-Earth is an extrasolar planet with a mass higher than Earth's, but substantially below those of the Solar System's ice giants, Uranus and Neptune, which are 14.5 and 17 times Earth's, respectively. The term "super-Earth" refers only to the mass of the planet, and so does not imply anything about the surface conditions or habitability. The alternative term "gas dwarfs" may be more accurate for those at the higher end of the mass scale, although "mini-Neptunes" is a more common term. Definition In general, super-Earths are defined by their masses, and the term does not imply temperatures, compositions, orbital properties, habitability, or environments. While sources generally agree on an upper bound of 10 Earth masses (~69% of the mass of Uranus, which is the Solar System's giant planet with the least mass), the lower bound varies from 1 or 1.9 to 5, with various other definitions appearing in the popular media. The term "super-Earth" is also used by astronomers to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Giant Planet
The giant planets constitute a diverse type of planet much larger than Earth. They are usually primarily composed of low-boiling-point materials (volatiles), rather than rock or other solid matter, but massive solid planets can also exist. There are four known giant planets in the Solar System: Jupiter, Saturn, Uranus and Neptune. Many extrasolar giant planets have been identified orbiting other stars. They are also sometimes called jovian planets, after Jupiter ("Jove" being another name for the Roman god "Jupiter"). They are also sometimes known as gas giants. However, many astronomers now apply the latter term only to Jupiter and Saturn, classifying Uranus and Neptune, which have different compositions, as ice giants. Both names are potentially misleading: all of the giant planets consist primarily of fluids above their critical points, where distinct gas and liquid phases do not exist. The principal components are hydrogen and helium in the case of Jupiter and Saturn, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brown Dwarf Desert
The brown-dwarf desert is a theorized range of orbits around a star within which brown dwarfs are unlikely to be found as companion objects. This is usually up to 5 AU around solar mass stars. The paucity of brown dwarfs in close orbits was first noted between 1998 and 2000 when a sufficient number of extrasolar planets had been found to perform statistical studies. Astronomers discovered there is a distinct shortage of brown dwarfs within 5 AU of the stars with companions, while there was an abundance of free-floating brown dwarfs being discovered. Subsequent studies have shown that brown dwarfs orbiting within 3–5 AU are found around less than 1% of stars with a mass similar to the Sun (). Of the brown dwarfs that were found in the brown-dwarf desert, most were found in multiple systems, suggesting that binarity was a key factor in the creation of brown-dwarf desert inhabitants. One of the many possible reasons for the existence of the desert relates to planetary ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brown-dwarf Desert
The brown-dwarf desert is a theorized range of orbits around a star within which brown dwarfs are unlikely to be found as companion objects. This is usually up to 5 AU around solar mass stars. The paucity of brown dwarfs in close orbits was first noted between 1998 and 2000 when a sufficient number of extrasolar planets had been found to perform statistical studies. Astronomers discovered there is a distinct shortage of brown dwarfs within 5 AU of the stars with companions, while there was an abundance of free-floating brown dwarfs being discovered. Subsequent studies have shown that brown dwarfs orbiting within 3–5 AU are found around less than 1% of stars with a mass similar to the Sun (). Of the brown dwarfs that were found in the brown-dwarf desert, most were found in multiple systems, suggesting that binarity was a key factor in the creation of brown-dwarf desert inhabitants. One of the many possible reasons for the existence of the desert relates to planetary ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Planetary Migration
Planetary migration occurs when a planet or other body in orbit around a star interacts with a disk of gas or planetesimals, resulting in the alteration of its orbital parameters, especially its semi-major axis. Planetary migration is the most likely explanation for hot Jupiters (exoplanets with Jovian masses but orbits of only a few days). The generally accepted theory of planet formation from a protoplanetary disk predicts that such planets cannot form so close to their stars, as there is insufficient mass at such small radii and the temperature is too high to allow the formation of rocky or icy planetesimals. It has also become clear that terrestrial-mass planets may be subject to rapid inward migration if they form while the gas disk is still present. This may affect the formation of the cores of the giant planets (which have masses of the order of 10 to 1000 Earth masses), if those planets form via the core-accretion mechanism. Types of disk Gas disk Observatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Exoplanets Discovered In 2019
This list of exoplanets discovered in 2019 is a list of confirmed exoplanets that were first observed during 2019. For exoplanets detected only by radial velocity, the listed value for mass is a lower limit. See Minimum mass for more information. {, class="wikitable plainrowheaders sortable" style="width: 100%; font-size: 83%; text-align: center;" !Name !data-sort-type="number", Mass () !data-sort-type="number", Radius () !data-sort-type="number", Orbital period, Period (days) !data-sort-type="number", Semi-major and semi-minor axes#Astronomy, Semi-major axis (Astronomical unit, AU) !data-sort-type="number", Planetary equilibrium temperature, Temp. (Kelvin, K) !Discovery method !data-sort-type="number", Distance (light year, ly) !data-sort-type="number", Host star mass () !data-sort-type="number", Effective temperature, Host star temp. (K) !Remarks , - , 7 Canis Majoris c , 0.87 , , 996.00 , 2.153 , , style="background:#00FF00", radial vel. , 64.6 , 1.34 , ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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