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HD 212771
HD 212771 is a solitary star in the southern zodiac constellation Aquarius. It has an apparent magnitude of 7.60, making it readily visible with binoculars but not the naked eye. Parallax measurements place the object at a distance of 364 light years, and is currently receding with a radial velocity of . HD 212771 has a stellar classification of G8 IV, indicating that it is a subgiant evolving towards the red giant branch after being an A-type main-sequence star for 1.7 billion years. It has 156% the mass of the Sun and 5 times its radius. It radiates at from its slightly enlarged photosphere at an effective temperature of 5,003 K, giving it a yellow-hue. Unlike most planetary hosts, HD 212771 is slightly metal deficient, and spins with a projected rotational velocity of about . Planetary system In 2010, a group of astronomers at the Keck Observatory surveyed several subgiant stars for extrasolar planets via Doppler spectroscopy They happened to find a massive ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HD 212771 B
HD 212771 b is an extrasolar planet orbiting the G-type star HD 212771 approximately 364 light years away in the constellation Aquarius. Nomenclature HD 212771 b is named Victoriapeak. The name was selected in the NameExoWorlds campaign by Hong Kong, during the 100th anniversary of the IAU. It is named after the Victoria Peak, the highest point on Hong Kong Island. The host star HD 212771 is named Lionrock, after the Lion Rock. Properties Orbit HD 212771 b's orbit period and distance are similar to Earth's, with the values being 380 days and 1.19 AU respectively. It orbits in a nearly perfect circular orbit compared to long period gas giants. Characteristics Due to the unknown orbital parameters, the planets true mass is not known, with a minimum of 2.39 times Jupiter's mass. HD 212771 b's radius is unknown, so NASA's ''Eyes on Exoplanets'' gives an estimate of 1.18 times the radius. See also * HD 4313 b * HD 181342 b * HD 206610 b * HD 180902 b * HD 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Effective Temperature
The effective temperature of a body such as a star or planet is the temperature of a black body that would emit the same total amount of electromagnetic radiation. Effective temperature is often used as an estimate of a body's surface temperature when the body's emissivity curve (as a function of wavelength) is not known. When the star's or planet's net emissivity in the relevant wavelength band is less than unity (less than that of a black body), the actual temperature of the body will be higher than the effective temperature. The net emissivity may be low due to surface or atmospheric properties, including greenhouse effect. Star The effective temperature of a star is the temperature of a black body with the same luminosity per ''surface area'' () as the star and is defined according to the Stefan–Boltzmann law . Notice that the total ( bolometric) luminosity of a star is then , where is the stellar radius. The definition of the stellar radius is obviously not stra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Victoria Peak
Victoria Peak is a hill on the western half of Hong Kong Island. It is also known as Mount Austin, and locally as The Peak only generally. With an elevation of , it is the highest hill on Hong Kong Island, ranked 29 in terms of elevation in Hong Kong. It is a major tourist attraction offering views of Central, Victoria Harbour, Lamma Island and the surrounding islands. The summit of Victoria Peak is occupied by a radio telecommunications facility and is closed to the public. The surrounding area of public parks, tourist facilities and high-value residential land is the area that is normally meant by the name ''The Peak''. ''The Peak'' also refers to Victoria Peak itself and its nearby areas, including Victoria Gap, Mount Kellett and Mount Gough. Sometimes Bowen Hill may also be included. History As early as the 19th century, the Peak attracted prominent European residents because of its panoramic view over the city and its temperate climate compared to the sub-tropica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lion Rock
Lion Rock, or less formally Lion Rock Hill, is a mountain in Hong Kong. It is located in Sha Tin District, between Kowloon Tong of Kowloon and Tai Wai of the New Territories, and is high. The peak consists of granite covered sparsely by shrubs. The Kowloon granite, which includes Lion Rock, is estimated to be around 140 million years old. Lion Rock is noted for its shape. Its resemblance to a crouching lion is most striking from the Choi Hung and San Po Kong areas in East Kowloon. A trail winds its way up the forested hillside to the top, culminating atop the "lion's head". The trail can be followed across the profile of the lion, eventually linking up with the MacLehose Trail. The rock provides a view of the city and Hong Kong Island in the distance. The entire mountain is located within Lion Rock Country Park, south of Hung Mui Kuk, Tai Wai and is made passable by vehicles by Lion Rock Tunnel, which connects Kowloon Tong and Tai Wai. Lion Rock is near another fam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Astronomical Union
The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and development through global cooperation. It was founded in 1919 and is based in Paris, France. The IAU is composed of individual members, who include both professional astronomers and junior scientists, and national members, such as professional associations, national societies, or academic institutions. Individual members are organised into divisions, committees, and working groups centered on particular subdisciplines, subjects, or initiatives. As of 2018, the Union had over 13,700 individual members, spanning 90 countries, and 82 national members. Among the key activities of the IAU is serving as a forum for scientific conferences. It sponsors nine annual symposia and holds a triannual General Assembly that sets policy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hong Kong
Hong Kong ( (US) or (UK); , ), officially the Hong Kong Special Administrative Region of the People's Republic of China (abbr. Hong Kong SAR or HKSAR), is a city and special administrative region of China on the eastern Pearl River Delta in South China. With 7.5 million residents of various nationalities in a territory, Hong Kong is one of the most densely populated places in the world. Hong Kong is also a major global financial centre and one of the most developed cities in the world. Hong Kong was established as a colony of the British Empire after the Qing Empire ceded Hong Kong Island from Xin'an County at the end of the First Opium War in 1841 then again in 1842.. The colony expanded to the Kowloon Peninsula in 1860 after the Second Opium War and was further extended when Britain obtained a 99-year lease of the New Territories in 1898... British Hong Kong was occupied by Imperial Japan from 1941 to 1945 during World War II; British administration resumed afte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NameExoWorlds
NameExoWorlds (also known as IAU NameExoWorlds) is the name of various projects managed by the International Astronomical Union (I.A.U.) to encourage names to be submitted for astronomical objects, which would later be considered for official adoption by the organization. History The first such project (NameExoWorlds I), in 2015, regarded the naming of stars and exoplanets. 573,242 votes were submitted by members by the time the contest closed on October 31, 2015, and the names of 31 exoplanets and 14 stars were selected from these. Many of the names chosen were based on world history, mythology and literature. In June 2019, another such project (NameExoWorlds II), in celebration of the organization's hundredth anniversary, in a project officially called IAU100 NameExoWorlds, welcomed countries of the world to submit names for exoplanets and their host stars. A star with an exoplanet was assigned to each country, and members of the public submitted names for them. In August 2 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jupiter
Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but slightly less than one-thousandth the mass of the Sun. Jupiter is the third brightest natural object in the Earth's night sky after the Moon and Venus, and it has been observed since prehistoric times. It was named after the Roman god Jupiter, the king of the gods. Jupiter is primarily composed of hydrogen, but helium constitutes one-quarter of its mass and one-tenth of its volume. It probably has a rocky core of heavier elements, but, like the other giant planets in the Solar System, it lacks a well-defined solid surface. The ongoing contraction of Jupiter's interior generates more heat than it receives from the Sun. Because of its rapid rotation, the planet's shape is an oblate spheroid: it has a slight but noticeable bulge around the equator. The outer atmospher ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Doppler Spectroscopy
Doppler spectroscopy (also known as the radial-velocity method, or colloquially, the wobble method) is an indirect method for finding extrasolar planets and brown dwarfs from radial-velocity measurements via observation of Doppler shifts in the spectrum of the planet's parent star. 1,018 extrasolar planets (about 19.5% of the total) have been discovered using Doppler spectroscopy, as of November 2022. History Otto Struve proposed in 1952 the use of powerful spectrographs to detect distant planets. He described how a very large planet, as large as Jupiter, for example, would cause its parent star to wobble slightly as the two objects orbit around their center of mass. He predicted that the small Doppler shifts to the light emitted by the star, caused by its continuously varying radial velocity, would be detectable by the most sensitive spectrographs as tiny redshifts and blueshifts in the star's emission. However, the technology of the time produced radial-velocity me ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extrasolar Planet
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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subgiant Star
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 that 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 V ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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