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List Of Nearest Black Holes
This is a list of known black holes that are close to the Solar System, which Earth is part of. It is thought that most black holes are solitary, but black holes in binary or larger systems are much easier to detect. Solitary black holes can generally only be detected by measuring their gravitational distortion of the light from more distant objects. As of February 2022, only one isolated black hole has been detected, OGLE-2011-BLG-0462, around 5,200 light-years away. For comparison, the nearest star to the Sun is about away, and the Milky Way galaxy is approximately 105,000 light years in diameter. List See also * List of black holes * List of most massive black holes * Lists of astronomical objects This is a list of lists, grouped by type of astronomical object. Solar System * List of Solar System objects * List of gravitationally rounded objects of the Solar System * List of Solar System objects most distant from the Sun * List of So ... * NGC 3201 – a g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Black Hole
A black hole is a region of spacetime where gravity is so strong that nothing, including light or other electromagnetic waves, has enough energy to escape it. The theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a black hole. The boundary of no escape is called the event horizon. Although it has a great effect on the fate and circumstances of an object crossing it, it has no locally detectable features according to general relativity. In many ways, a black hole acts like an ideal black body, as it reflects no light. Moreover, quantum field theory in curved spacetime predicts that event horizons emit Hawking radiation, with the same spectrum as a black body of a temperature inversely proportional to its mass. This temperature is of the order of billionths of a kelvin for stellar black holes, making it essentially impossible to observe directly. Objects whose gravitational fields are too strong for light to escape were fir ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Georgia State University
Georgia State University (Georgia State, State, or GSU) is a public research university in Atlanta, Georgia. Founded in 1913, it is one of the University System of Georgia's four research universities. It is also the largest institution of higher education by enrollment based in Georgia and is in the top 10 in the nation in number of students with a diverse majority-minority student population of around 54,000 students, including approximately 33,000 undergraduate and graduate students at the main campus downtown. Georgia State is classified among " R1: Doctoral Universities – Very High Research Activity". The university's over $200 million in research expenditures for the 2018 fiscal year ranked first in the nation among universities without an engineering, medical, or agricultural school for the third year in a row. The university is the most comprehensive public institution in Georgia, offering more than 250 degree programs in over 100 fields of study spread across 10 ac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
A0620-00
A0620-00 (abbreviated from 1A 0620-00) is a binary star system in the constellation of Monoceros, with an apparent magnitude of 11.2 A0620-00 consists of two objects. The first object is a K-type main-sequence star. The second object cannot be seen, but based on its calculated mass of , it is too massive to be a neutron star and must therefore be a stellar-mass black hole. The two objects orbit each other every 7.75 hours. At a distance of roughly away, the black hole of A0620-00 would be one of the nearest known black holes to the Solar System, closer than GRO J1655-40. A0620-00 has undergone two X-ray outbreaks. The first one was in 1917. The second burst, in 1975, was detected by the Ariel 5 satellite. During that time, A0620-00 was the brightest X-ray point source. It is now classified as an X-ray nova. Its black hole nature was determined in 1986. The black hole in A0620-00 pulls matter from the K-type star into an accretion disk. The accretion disk emi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
G-type Main-sequence Star
A G-type main-sequence star (Spectral type: G-V), also often, and imprecisely called a yellow dwarf, or G star, is a main-sequence star (luminosity class V) of spectral type G. Such a star has about 0.9 to 1.1 solar masses and an effective temperature between about 5,300 and 6,000 K. Like other main-sequence stars, a G-type main-sequence star is converting the element hydrogen to helium in its core by means of nuclear fusion, but can also fuse helium when hydrogen runs out. The Sun, the star in the center of the Solar System to which the Earth is gravitationally bound, is an example of a G-type main-sequence star (G2V type). Each second, the Sun fuses approximately 600 million tons of hydrogen into helium in a process known as the proton–proton chain (4 hydrogens form 1 helium), converting about 4 million tons of matter to energy. Besides the Sun, other well-known examples of G-type main-sequence stars include Alpha Centauri, Tau Ceti, Capella and 51 Pegasi. The te ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gaia BH1
Gaia BH1 (Gaia DR3 4373465352415301632) is a binary system consisting of a G-type main-sequence star and a likely stellar-mass black hole, located about away from the Solar System in the constellation of Ophiuchus. , it is the nearest known system that astronomers are reasonably confident contains a black hole, followed by A0620-00. The star and black hole orbit each other with a period of 185.59 days and an eccentricity of 0.45. The star is similar to the Sun, with about and , and a temperature of about , while the black hole has a mass of about . Given this mass, the black hole's Schwarzschild radius should be about . Discovery Gaia BH1 was discovered in 2022 via astrometric observations with Gaia, and also observed via radial velocity. The discovery team found no astrophysical scenario that could explain the observed motion of the G-type star, other than a black hole. The system differs from "black hole impostors" such as LB-1 and HR 6819 in that the evidence ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
B-type Main-sequence Star
A B-type main-sequence star (B V) is a main-sequence (hydrogen-burning) star of spectral type B and luminosity class V. These stars have from 2 to 16 times the mass of the Sun and surface temperatures between 10,000 and 30,000 K. B-type stars are extremely luminous and blue. Their spectra have neutral helium, which are most prominent at the B2 subclass, and moderate hydrogen lines. Examples include Regulus and Algol A. This class of stars was introduced with the Harvard sequence of stellar spectra and published in the ''Revised Harvard photometry'' catalogue. The definition of type B-type stars was the presence of non-ionized helium lines with the absence of singly ionized helium in the blue-violet portion of the spectrum. All of the spectral classes, including the B type, were subdivided with a numerical suffix that indicated the degree to which they approached the next classification. Thus B2 is 1/5 of the way from type B (or B0) to type A. Later, however, more refined ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
V Puppis
V Puppis (V Pup) is a star system in the constellation Puppis. Its apparent magnitude is 4.41. There is a binary star system at the center with a B1 dwarf orbiting a B3 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 ... star. They have an orbital period of 1.45 days and a distance of only 15 solar radii apart. However, the system moves back and forth, indicating that there is a massive object orbiting them with a period around 5.47 years. Based on the mass of the object, its lack of a visible spectrum, and circumstellar matter in the system with many heavy elements (as would be produced by a past supernova in the system), it is probably a black hole. However, a follow-up study could not confirm this object, but found signs that there may be a third object w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
K-type Main-sequence Star
A K-type main-sequence star, also referred to as a K-type dwarf or an orange dwarf, is a main-sequence (hydrogen-burning) star of spectral type K and luminosity class V. These stars are intermediate in size between red M-type main-sequence stars ("red dwarfs") and yellow/white G-type main-sequence stars. They have masses between 0.6 and 0.9 times the mass of the Sun and surface temperatures between 3,900 and 5,300 K. These stars are of particular interest in the search for extraterrestrial life due to their stability and long lifespan. Well-known examples include Alpha Centauri B (K1 V) and Epsilon Indi (K5 V). Spectral standard stars The revised Yerkes Atlas system (Johnson & Morgan 1953) listed 12 K-type dwarf spectral standard stars, however not all of these have survived to this day as standards. The "anchor points" of the MK classification system among the K-type main-sequence dwarf stars, i.e. those standard stars that have remain unchanged over the years, are: *Sigm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gaia DR2 3509370326763016704
In Greek mythology, Gaia (; from Ancient Greek , a poetical form of , 'land' or 'earth'),, , . also spelled Gaea , is the personification of the Earth and one of the Greek primordial deities. Gaia is the ancestral mother—sometimes parthenogenic—of all life. She is the mother of Uranus (the sky), from whose sexual union she bore the Titans (themselves parents of many of the Olympian gods), the Cyclopes, and the Giants; as well as of Pontus (the sea), from whose union she bore the primordial sea gods. Her equivalent in the Roman pantheon was Terra.''Larousse Desk Reference Encyclopedia'', The Book People, Haydock, 1995, p. 215. Etymology The Greek name Γαῖα (''Gaia'' or ) is a mostly epic, collateral form of Attic (''Gē'' ), and Doric (''Ga'' ), perhaps identical to (''Da'' ), both meaning "Earth". The word is of uncertain origin. Beekes suggested a Pre-Greek origin.Robert S. P. Beekes, ''Etymological Dictionary of Greek'', Brill, 2009, pp. 269–270 (''s.v.' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar Mass
The solar mass () is a standard unit of mass in astronomy, equal to approximately . It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxies and black holes. It is approximately equal to the mass of the Sun. This equates to about two nonillion (short scale), two quintillion (long scale) kilograms or 2000 quettagrams: The solar mass is about times the mass of Earth (), or times the mass of Jupiter (). History of measurement The value of the gravitational constant was first derived from measurements that were made by Henry Cavendish in 1798 with a torsion balance. The value he obtained differs by only 1% from the modern value, but was not as precise. The diurnal parallax of the Sun was accurately measured during the transits of Venus in 1761 and 1769, yielding a value of (9 arcseconds, compared to the present value of ). From the value of the diurnal parallax, one can determine the distance to the Sun from the geomet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stellar Classification
In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the rainbow of colors interspersed with spectral lines. Each line indicates a particular chemical element or molecule, with the line strength indicating the abundance of that element. The strengths of the different spectral lines vary mainly due to the temperature of the photosphere, although in some cases there are true abundance differences. The ''spectral class'' of a star is a short code primarily summarizing the ionization state, giving an objective measure of the photosphere's temperature. Most stars are currently classified under the Morgan–Keenan (MK) system using the letters ''O'', ''B'', ''A'', ''F'', ''G'', ''K'', and ''M'', a sequence from the hottest (''O'' type) to the coolest (''M'' type). Each letter class is then subdivi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
