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38 Leonis Minoris
38 Leonis Minoris is a binary star system in the northern constellation of Leo Minor. It shines with a combined light of apparent magnitude 5.84, which indicates it a dimly visible to the naked eye under good viewing conditions. An annual parallax shift of 19.11 mas provides a distance estimate of around 171 light years. It has a relatively high proper motion, traversing the celestial sphere at a rate of 0.226 arcseconds per year, and is moving away from the Sun with a radial velocity of +31 km/s. This is a single-lined spectroscopic binary with an orbital period of 7.8 days and a low eccentricity of 0.023 – nearly circular. The visible component has a stellar classification of G0 IV, matching a G-type subgiant star that is exhausting the hydrogen at its core and evolving into a giant. It is about two billion years old with 1.68 times the mass of the Sun and is spinning with a projected rotational velocity of 14.5 km/s. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leo Minor
Leo Minor is a small and faint constellation in the northern celestial hemisphere. Its name is Latin for "the smaller lion", in contrast to Leo, the larger lion. It lies between the larger and more recognizable Ursa Major to the north and Leo to the south. Leo Minor was not regarded as a separate constellation by classical astronomers; it was designated by Johannes Hevelius in 1687. There are 37 stars brighter than apparent magnitude 6.5 in the constellation; three are brighter than magnitude 4.5. 46 Leonis Minoris, an orange giant of magnitude 3.8, is located some 95 light-years from Earth. At magnitude 4.4, Beta Leonis Minoris is the second-brightest star and the only one in the constellation with a Bayer designation. It is a binary star, the brighter component of which is an orange giant and the fainter a yellow-white main sequence star. The third-brightest star is 21 Leonis Minoris, a rapidly rotating white main-sequence star of avera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stellar Core
A stellar core is the extremely hot, dense region at the center of a star. For an ordinary main sequence star, the core region is the volume where the temperature and pressure conditions allow for energy production through thermonuclear fusion of hydrogen into helium. This energy in turn counterbalances the mass of the star pressing inward; a process that self-maintains the conditions in thermal and hydrostatic equilibrium. The minimum temperature required for stellar hydrogen fusion exceeds 107 K (), while the density at the core of the Sun is over . The core is surrounded by the stellar envelope, which transports energy from the core to the stellar atmosphere where it is radiated away into space. Main sequence Main sequence stars are distinguished by the primary energy-generating mechanism in their central region, which joins four hydrogen nuclei to form a single helium atom through thermonuclear fusion. The Sun is an example of this class of stars. Once stars with the mass ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Durchmusterung Objects
In astronomy, Durchmusterung or Bonner Durchmusterung (BD) is an astrometric star catalogue of the whole sky, compiled by the Bonn Observatory in Germany from 1859 to 1903. The name comes from ('run-through examination'), a German word used for a systematic survey of objects or data. The term has sometimes been used for other astronomical surveys, including not only stars, but also the search for other celestial objects. Special tasks include celestial scanning in electromagnetic wavelengths shorter or longer than visible light waves. Original catalog The 44 years of work on the Bonner Durchmusterung (abbreviated BD), initiated by Friedrich Argelander and largely carried out by his assistants, resulted in a catalogue of the positions and apparent magnitudes of approximately 325,000 stars to apparent magnitude 9–10. The catalogue was accompanied by charts plotting the positions of the stars, and was the basis for the ''Astronomische Gesellschaft Katalog'' (AGK) and ''Smithsonia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flamsteed Objects
John Flamsteed (19 August 1646 – 31 December 1719) was an English astronomer and the first Astronomer Royal. His main achievements were the preparation of a 3,000-star catalogue, ''Catalogus Britannicus'', and a star atlas called ''Atlas Coelestis'', both published posthumously. He also made the first recorded observations of Uranus, although he mistakenly catalogued it as a star, and he laid the foundation stone for the Royal Greenwich Observatory. Life Flamsteed was born in Denby, Derbyshire, England, the only son of Stephen Flamsteed and his first wife, Mary Spadman. He was educated at the free school of Derby and at Derby School, in St Peter's Churchyard, Derby, near where his father carried on a malting business. At that time, most masters of the school were Puritans. Flamsteed had a solid knowledge of Latin, essential for reading the scientific literature of the day, and a love of history, leaving the school in May 1662.Birks, John L. (1999) ''John Flamsteed, the f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spectroscopic Binaries
A binary star is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved using a telescope as separate stars, in which case they are called ''visual binaries''. Many visual binaries have long orbital periods of several centuries or millennia and therefore have orbits which are uncertain or poorly known. They may also be detected by indirect techniques, such as spectroscopy (''spectroscopic binaries'') or astrometry (''astrometric binaries''). If a binary star happens to orbit in a plane along our line of sight, its components will eclipse and transit each other; these pairs are called ''eclipsing binaries'', or, together with other binaries that change brightness as they orbit, ''photometric binaries''. If components in binary star systems are close enough they can gravitationally distort their mutual outer stellar atmospheres. In some cases, these ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
G-type Subgiants
Gaea Gaea is one of the Elder Gods of Earth. Gaia Gaia, also known as the Guardian of the Universal Amalgamator, is a fictional superhero, depicted as possibly being a mutant or extraterrestrial. Created by Larry Hama, she first appeared in ''Generation X'' #37. Not much is known about Gaia's origin besides her having spent thousands of years chained to the Universal Amalgamator at the end of Time, a device that would be used to merge all sentient consciousnesses into one being.''Generation X'' #37 Gaia was apparently the safeguard that was supposed to prevent the Amalgamator from being activated by malicious people. She even claimed that her entire galaxy was wiped out at one point for her refusing to activate the Amalgamator.''Generation X'' #38 However, when M-Plate, the synthesis of Emplate and M, tried to have Synch use his power to tap into Gaia's and activate the Amalgamator, Everett refused. The Citadel of the Universal Amalgamator began to crumble around them and G ... [...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 straightf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photosphere
The photosphere is a star's outer shell from which light is radiated. The term itself 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. 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 deepest region of a luminous object, usually a star, that is transparent to photons of certain wavelengths. Temperature The surface of a star is defined to have a temperature given by the effective temperature in the Stefan–Boltzmann law. 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. Composition of the Sun The Sun is composed primarily of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sun's Luminosity
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 does not include the solar neutrino luminosity, which would add , or , i.e. a total of (the mean energy of the solar photons is 26 MeV and that of the solar neutrinos 0.59 MeV, i.e. 2.27%; the Sun emits photons and as many neutrinos each second, of which per m2 reach the Earth each second). 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 sola ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stellar Spectrum
Astronomical spectroscopy is the study of astronomy using the techniques of spectroscopy to measure the spectrum of electromagnetic radiation, including visible light, ultraviolet, X-ray, infrared and radio waves that radiate from stars and other celestial objects. A stellar spectrum can reveal many properties of stars, such as their chemical composition, temperature, density, mass, distance and luminosity. Spectroscopy can show the velocity of motion towards or away from the observer by measuring the Doppler shift. Spectroscopy is also used to study the physical properties of many other types of celestial objects such as planets, nebulae, galaxies, and active galactic nuclei. Background Astronomical spectroscopy is used to measure three major bands of radiation in the electromagnetic spectrum: visible light, radio waves, and X-rays. While all spectroscopy looks at specific bands of the spectrum, different methods are required to acquire the signal depending on the frequency. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abundance Of The Chemical Elements
The abundance of the chemical elements is a measure of the Type–token distinction#Occurrences, occurrence of the chemical elements relative to all other elements in a given environment. Abundance is measured in one of three ways: by the mass fraction (chemistry), mass-fraction (the same as weight fraction); by the mole fraction, mole-fraction (fraction of atoms by numerical count, or sometimes fraction of molecules in gases); or by the volume fraction, volume-fraction. Volume-fraction is a common abundance measure in mixed gases such as planetary atmospheres, and is similar in value to molecular mole-fraction for gas mixtures at relatively low densities and pressures, and ideal gas mixtures. Most abundance values in this article are given as mass-fractions. For example, the abundance of oxygen in pure water can be measured in two ways: the ''mass fraction'' is about 89%, because that is the fraction of water's mass which is oxygen. However, the ''mole-fraction'' is about 33% becau ... [...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. The magnetic field of a star interacts with the stellar wind. As the wind moves away from the star its rate of angular velocity slows. 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 star is being obse ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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