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K2-66b
K2-66b is a confirmed mega-Earth orbiting the subgiant K2-66, about from Earth in the direction of Aquarius (constellation), Aquarius. It is an extremely hot and dense planet heavier than Neptune, but with only about half its radius. Planet properties Mass, radius, and temperature K2-66b is a mega-Earth with radius and mass . The planet's temperature is highly variable due to the variability of its host star, and is currently estimated at . Orbit The Exoplanet, planet orbits every 5.07 days at 0.06 Astronomical unit, AU. It orbits within a "photoevaporation desert", where orbiting exoplanets should be very uncommon. K2-66b's orbit is nearly circular. Star The star, K2-66 is a G-type main-sequence star, G1 sub-giant in Aquarius (constellation), Aquarius. It has a Solar analog, sun-like temperature of 5887 Kelvin, K, which corresponds to its Stellar classification, spectral class and is very close to that of throtationally variablestaKepler-130 It has a radius of and a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mega-Earth
A mega-Earth is a proposed neologism for a massive terrestrial exoplanet that is at least ten times the mass of Earth. Mega-Earths would be substantially more massive than super-Earths (terrestrial and ocean planets with masses around 5–10 Earths). The term "mega-Earth" was coined in 2014, when Kepler-10c was revealed to be a Neptune-mass planet with a density considerably greater than that of Earth, though it has since been determined to be a typical volatile-rich planet weighing just under half that mass. Examples Kepler-10c was the first exoplanet to be classified as a mega-Earth. At the time of its discovery, it was believed to have a mass around 17 times that of Earth () and a radius around 2.3 times Earth's (), giving it a high density that implied a mainly rocky composition. However, several follow-up radial velocity studies produced different results for Kepler-10c's mass, all much below the original estimate. In 2017, a more careful analysis using data from multiple dif ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Exoplanets Discovered In 2016
This is a list of exoplanets discovered in 2016. As of 2024, 2016 was the year with the most discoveries of exoplanets. For exoplanets detected only by radial velocity, the mass value is actually a lower limit. (See Minimum mass for more information) List Excluded objects and former candidate The majority of exoplanet discoveries in 2016 were from a paper by Morton ''et al.'' that statistically validated over 1,000 Kepler planets. This statistical validation did not involve mass measurements, and some transiting objects validated as planets were later shown (or even previously known) to be small stars. Such cases include Kepler-469 (KOI-126), Kepler-470 (KOI-129), Kepler-486 (KOI-189), Kepler-488 (KOI-194), Kepler-503 (KOI-242), Kepler-628 (KOI-631), Kepler-699 (KOI-846), Kepler-706 (KOI-855), Kepler-807 (KOI-1288), Kepler-840 (KOI-1416), and Kepler-854 (KOI-1450). In another two cases, Kepler-492 (KOI-205) and Kepler-494 (KOI-219), the companions are brown dwarfs with masses ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extrasolar Planets Encyclopaedia
The Extrasolar Planets Encyclopaedia (also known as Encyclopaedia of exoplanetary systems and Catalogue of Exoplanets) is an astronomy website, founded in Paris, France at the Meudon Observatory by Jean Schneider in February 1995, which maintains a database of all the currently known and candidate extrasolar planets, with individual pages for each planet and a full list interactive catalog spreadsheet. The main catalogue comprises databases of all of the currently confirmed extrasolar planets as well as a database of unconfirmed planet detections. The databases are frequently updated with new data from peer-reviewed publications and conferences. In their respective pages, the planets are listed along with their basic properties, including the year of planet's discovery, mass, radius, orbital period, semi-major axis, eccentricity, inclination, longitude of periastron, time of periastron, maximum time variation, and time of transit, including all error range values. The ind ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apparent Magnitude
Apparent magnitude () is a measure of the Irradiance, brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction (astronomy), extinction of the object's light caused by interstellar dust along the sightline, line of sight to the observer. Unless stated otherwise, the word ''magnitude'' in astronomy usually refers to a celestial object's apparent magnitude. The magnitude scale likely dates to before the ancient Ancient Greek astronomy#Astronomy in the Greco-Roman and Late Antique eras, Roman astronomer Ptolemy, Claudius Ptolemy, whose Star catalogue, star catalog popularized the system by listing stars from First-magnitude star, 1st magnitude (brightest) to 6th magnitude (dimmest). The modern scale was mathematically defined to closely match this historical system by Norman Robert Pogson, Norman Pogson in 1856. The scale is reverse logarithmic scale, logarithmic: ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exoplanets Discovered In 2017
An exoplanet or extrasolar planet is a planet outside the Solar System. The first confirmed detection of an exoplanet was in 1992 around a pulsar, and the first detection around a main-sequence star was in 1995. A different planet, first detected in 1988, was confirmed in 2003. In 2016, it was recognized that the first possible evidence of an exoplanet had been noted in 1917. In collaboration with ground-based and other space-based observatories the James Webb Space Telescope (JWST) is expected to give more insight into exoplanet traits, such as their composition, environmental conditions, and potential for life. 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stellar Evolution
Stellar evolution is the process by which a star changes over the course of time. Depending on the mass of the star, its lifetime can range from a few million years for the most massive to trillions of years for the least massive, which is considerably longer than the current age of the universe. The table shows the lifetimes of stars as a function of their masses. All stars are formed from Gravitational collapse, collapsing clouds of gas and dust, often called nebulae or molecular clouds. Over the course of millions of years, these protostars settle down into a state of equilibrium, becoming what is known as a main sequence star. Nuclear fusion powers a star for most of its existence. Initially the energy is generated by the fusion of hydrogen atoms at the stellar core, core of the main-sequence star. Later, as the preponderance of atoms at the core becomes helium, stars like the Sun begin to fuse hydrogen along a spherical shell surrounding the core. This process causes the st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lava Planet
A lava planet is a type of terrestrial planet, with a surface mostly or entirely covered by molten lava. Situations where such planets could exist include a young terrestrial planet just after its formation, a planet that has recently suffered a large collision event, or a planet orbiting very close to its star, causing intense irradiation and tidal forces to melt its surface. Factors and characteristics Lava planets would probably orbit extremely close to their parent star. In planets with eccentric orbits, the gravity from the nearby star would distort the planet periodically, with the resulting friction producing internal heat. This tidal heating could melt rocks into magma, which would then erupt through volcanoes. This would be similar to the Solar System moon Io, orbiting close to its parent Jupiter. Io is the most geologically active world in the Solar System, with hundreds of volcanic centres and extensive lava flows. Lava worlds orbiting extremely closely to the pare ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Exoplanets Discovered In 2017 ...
This is a list of exoplanets discovered in 2017. For exoplanets detected only by radial velocity, the mass value is actually a lower limit. (See Minimum mass for more information) Specific exoplanet lists References {{Exoplanet 2017 * exoplanets An exoplanet or extrasolar planet is a planet outside the Solar System. The first confirmed detection of an exoplanet was in 1992 around a pulsar, and the first detection around a main-sequence star was in 1995. A different planet, first detec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Density
Density (volumetric mass density or specific mass) is the ratio of a substance's mass to its volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' (or ''d'') can also be used: \rho = \frac, where ''ρ'' is the density, ''m'' is the mass, and ''V'' is the volume. In some cases (for instance, in the United States oil and gas industry), density is loosely defined as its weight per unit volume, although this is scientifically inaccurate this quantity is more specifically called specific weight. For a pure substance, the density is equal to its mass concentration. Different materials usually have different densities, and density may be relevant to buoyancy, purity and packaging. Osmium is the densest known element at standard conditions for temperature and pressure. To simplify comparisons of density across different systems of units, it is sometimes replaced by the dimensionless quantity "relative den ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subgiant
A subgiant is a star that is brighter than a normal main-sequence star of the same spectral class, but not as bright as giant stars. The term subgiant is applied both to a particular spectral luminosity class and to a stage in the evolution of a star. Yerkes luminosity class IV The term subgiant was first used in 1930 for class G and early K stars with absolute magnitudes between +2.5 and +4. These were noted as being part of a continuum of stars between obvious main-sequence stars such as the Sun and obvious giant stars such as Aldebaran, although less numerous than either the main sequence or the giant stars. The Yerkes spectral classification system is a two-dimensional scheme that uses a letter and number combination to denote the temperature of a star (e.g. A5 or M1) and a Roman numeral to indicate the luminosity relative to other stars of the same temperature. Luminosity class IV stars are the subgiants, located between main-sequence stars (luminosity class&n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
