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β Virginis
Beta Virginis, a name Latinised from β Virginis, is a star in the equatorial constellation of Virgo. It has the proper name Zavijava (), and, despite its designation 'beta', is the fifth-brightest star in Virgo with an apparent visual magnitude of 3.604. The distance to this star is around 35.7 light-years based on parallax; it is drifting further away with a radial velocity of +4.1 km/s. It is 0.69 of a degree north of the ecliptic, so it can be occulted by the Moon and (rarely) by planets. The next planetary occultation of Beta Virginis will take place on 9 November 2210, by Venus; although an occultation by the same planet might be visible on 11 August 2069 from the South Pole. Properties This is an F-type main-sequence star with a stellar classification of F9 V, which means it is generating energy through core hydrogen fusion. Sun-like oscillations have been detected in Beta Virginis, allowing its internal structure to be modeled in more detail. I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virgo (constellation)
Virgo is one of the constellations of the zodiac. The name is for maiden in Latin and its traditional astrological symbol is . Between Leo (constellation), Leo to the west and Libra (constellation), Libra to the east, lying in the south, it is the second-largest constellation in the sky (after Hydra (constellation), Hydra) and the largest constellation in the zodiac. The ecliptic intersects the celestial equator within this constellation and Pisces (constellation), Pisces. Underlying these technical two definitions, the sun passes directly overhead of the equator, within this constellation, at the September equinox. Virgo can be easily found through its brightest star, Spica, (in Latin "grain headed"). Location Virgo is prominent in the spring sky in the Northern Hemisphere, visible all night in March and April. As the largest zodiac constellation, the Sun takes 44 days to pass through it, longer than any other. From 1990 and until 2062, this will take place from September 16 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
F-type Main-sequence Star
An F-type main-sequence star (F V) is a main-sequence, hydrogen-fusing star of spectral type F and luminosity class V. These stars have from 1.0 to 1.4 times the mass of the Sun and surface temperatures between 6,000 and 7,600 K.Tables VII and VIII. This temperature range gives the F-type stars a whitish hue when observed by the atmosphere. Because a main-sequence star is referred to as a dwarf star, this class of star may also be termed a yellow-white dwarf (not to be confused with white dwarfs, remnant stars that are a possible final stage of stellar evolution). Notable examples include Procyon A, Gamma Virginis A and B, and KIC 8462852. Spectral standard stars The revised Yerkes Atlas system (Johnson & Morgan 1953) listed a dense grid of F-type dwarf spectral standard stars; however, not all of these have survived to this day as stable standards. The ''anchor points'' of the MK spectral classification system among the F-type main-sequence dwarf stars, i.e. thos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jupiter Mass
The Jupiter mass, also called Jovian mass, is the unit of mass equal to the total mass of the planet Jupiter. This value may refer to the mass of the planet alone, or the mass of the entire Jovian system to include the moons of Jupiter. Jupiter is by far the most massive planet in the Solar System. It is approximately 2.5 times as massive as all of the other planets in the Solar System combined. Jupiter mass is a common unit of mass in astronomy that is used to indicate the masses of other similarly-sized objects, including the outer planets, extrasolar planets, and brown dwarfs, as this unit provides a convenient scale for comparison. Current best estimates The current best known value for the mass of Jupiter can be expressed as : M_\mathrm=(1.89813 \pm 0.00019)\times10^ \text, which is about as massive as the Sun (is about ): M_\mathrm=\frac M_ \approx (9.547919 \pm 0.000002) \times10^ M_. Jupiter is 318 times as massive as Earth: M_\mathrm = 3.1782838 \times 10^2 M_\o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jovian Planet
Jovian is the adjectival form of Jupiter and may refer to: * Jovian (emperor) (Flavius Iovianus Augustus), Roman emperor (363–364 AD) * Jovians and Herculians, Roman imperial guard corps * Jovian (lemur), a Coquerel's sifaka known for ''Zoboomafoo'' * Jovian (fiction), a hypothetical or fictional native inhabitant of the planet Jupiter * Jovian planet or giant planet, any large gaseous planet * Jovians, a non-playable race in ''Eve Online'' See also * Iovianus Pontanus (Giovanni Pontano), an Italian humanist poet * '' Jovian Chronicles'', a science-fiction game * Jovian–Plutonian gravitational effect, an April Fools' Day hoax * Jovian system, the system of Jupiter's moons * Joviânia, a small town in Brazil * Jupiter * Jupiter (mythology) Jupiter ( or , from Proto-Italic language, Proto-Italic "day, sky" + "father", thus "sky father" Greek: Zeus, Δίας or Zeus, Ζεύς), also known as Jove (nominative case, nom. and genitive case, gen. ), is the sky god, ... [...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, such as the 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photosphere
The photosphere is a star's outer shell from which light is radiated. It extends into a star's surface until the plasma becomes opaque, equivalent to an optical depth of approximately , or equivalently, a depth from which 50% of light will escape without being scattered. A photosphere is the region of a luminous object, usually a star, that is transparent to photons of certain wavelengths. Stars, except neutron stars, have no solid or liquid surface. Therefore, the photosphere is typically used to describe the Sun's or another star's visual surface. Etymology The term ''photosphere'' is derived from Ancient Greek roots, φῶς, φωτός/''phos'', ''photos'' meaning "light" and σφαῖρα/''sphaira'' meaning "sphere", in reference to it being a spherical surface that is perceived to emit light. Temperature The surface of a star is defined to have a temperature given by the effective temperature in the Stefan–Boltzmann law. Various stars have photospheres of vari ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Luminosity Of The Sun
The solar luminosity () is a unit of radiant flux ( power emitted in the form of photons) conventionally used by astronomers to measure the luminosity of stars, galaxies and other celestial objects in terms of the output of the Sun. One nominal solar luminosity is defined by the International Astronomical Union to be . This corresponds almost exactly to a bolometric absolute magnitude of +4.74. The Sun is a weakly variable star, and its actual luminosity therefore fluctuates. The major fluctuation is the eleven-year solar cycle (sunspot cycle) that causes a quasi-periodic variation of about ±0.1%. Other variations over the last 200–300 years are thought to be much smaller than this. Determination Solar luminosity is related to solar irradiance (the solar constant). Slow changes in the axial tilt of the planet and the shape of its orbit cause cyclical changes to the solar irradiance. The result is orbital forcing that causes the Milankovitch cycles, which determine Earthl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helium
Helium (from ) is a chemical element; it has chemical symbol, symbol He and atomic number 2. It is a colorless, odorless, non-toxic, inert gas, inert, monatomic gas and the first in the noble gas group in the periodic table. Its boiling point is the lowest among all the Chemical element, elements, and it does not have a melting point at standard pressures. It is the second-lightest and second-most Abundance of the chemical elements, abundant element in the observable universe, after hydrogen. It is present at about 24% of the total elemental mass, which is more than 12 times the mass of all the heavier elements combined. Its abundance is similar to this in both the Sun and Jupiter, because of the very high nuclear binding energy (per nucleon) of helium-4 with respect to the next three elements after helium. This helium-4 binding energy also accounts for why it is a product of both nuclear fusion and radioactive decay. The most common isotope of helium in the universe is helium-4, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metal-rich
In astronomy, metallicity is the Abundance of the chemical elements, abundance of Chemical element, elements present in an object that are heavier than hydrogen and helium. Most of the normal currently detectable (i.e. non-Dark matter, dark) matter in the universe is either hydrogen or helium, and astronomers use the word ''metals'' as convenient shorthand for ''all elements except hydrogen and helium''. This word-use is distinct from the conventional chemical or physical definition of a metal as an electrically conducting element. Stars and nebulae with relatively high abundances of heavier elements are called ''metal-rich'' when discussing metallicity, even though many of those elements are called ''Nonmetal (chemistry), nonmetals'' in chemistry. Metals in early spectroscopy In 1802, William Hyde WollastonMelvyn C. UsselmanWilliam Hyde WollastonEncyclopædia Britannica, retrieved 31 March 2013 noted the appearance of a number of dark features in the solar spectrum. In 1814, Jo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Main Sequence
In astronomy, the main sequence is a classification of stars which appear on plots of stellar color index, color versus absolute magnitude, brightness as a continuous and distinctive band. Stars on this band are known as main-sequence stars or dwarf stars, and positions of stars on and off the band are believed to indicate their physical properties, as well as their progress through several types of star life-cycles. These are the most numerous true stars in the universe and include the Sun. Color-magnitude plots are known as Hertzsprung–Russell diagrams after Ejnar Hertzsprung and Henry Norris Russell. After condensation and ignition of a star, it generates thermal energy in its dense stellar core, core region through nuclear fusion of hydrogen into helium. During this stage of the star's lifetime, it is located on the main sequence at a position determined primarily by its mass but also based on its chemical composition and age. The cores of main-sequence stars are in hydros ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Projected Rotational Velocity
Stellar rotation is the angular motion of a star about its axis. The rate of rotation can be measured from the spectrum of the star, or by timing the movements of active features on the surface. The rotation of a star produces an equatorial bulge due to centrifugal force. As stars are not solid bodies, they can also undergo differential rotation. Thus the equator of the star can rotate at a different angular velocity than the higher latitudes. These differences in the rate of rotation within a star may have a significant role in the generation of a stellar magnetic field. In its turn, the magnetic field of a star interacts with the stellar wind. As the wind moves away from the star its angular speed decreases. The magnetic field of the star interacts with the wind, which applies a drag to the stellar rotation. As a result, angular momentum is transferred from the star to the wind, and over time this gradually slows the star's rate of rotation. Measurement Unless a sta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar Oscillation
Helioseismology is the study of the structure and dynamics of the Sun through its oscillations. These are principally caused by sound waves that are continuously driven and damped by convection near the Sun's surface. It is similar to geoseismology, or asteroseismology, which are respectively the studies of the Earth or stars through their oscillations. While the Sun's oscillations were first detected in the early 1960s, it was only in the mid-1970s that it was realized that the oscillations propagated throughout the Sun and could allow scientists to study the Sun's deep interior. The term was coined by Douglas Gough in the 90s. The modern field is separated into global helioseismology, which studies the Sun's resonant modes directly, and local helioseismology, which studies the propagation of the component waves near the Sun's surface. Helioseismology has contributed to a number of scientific breakthroughs. The most notable was to show that the anomaly in the predicted neutri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
