Light and heat of the stars themselves can be issued. Previous position that these stars are fixed, so the name stars. In fact, no stars are also in motion, just as far from Earth, is not easy to change their position
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No. 3
Itself to light, heat objects. Imperceptible because of its location changes within a short time, hence the name. According to brightness, brightness can be divided into multiple levels. Ershibasu origin of the name as "stars." Also refers to the common stars. "Spring and Autumn duke seven years": "Summer in April Xin Mao, night, stars were not seen." "Kung-yang Zhuang public for seven years": "What those stars? USS also." Yan Xu Shu: "days regular places, so that the stars carry on through. Introduction to time series seen in days, so that the transfer of USS carry on. "" Ming Shi Tianwen Chih-yi ":" From this examination of the star there is a fixed shift, the truth of it. "
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No. 4
Light and heat can be issued their own objects, such as the Vega, the sun. The location of the past that these objects are stationary, so called stars. Sports stars are also in fact.
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No. 5
Composed of stars from the hot gas, energy glowing spherical or almost spherical celestial bodies themselves. Nearest star from Earth is the sun. Currently there are 12 planets in the solar system are: Mercury, Venus, Earth, Mars, Ceres, Jupiter, Saturn, Uranus, Neptune, Pluto (due to the new definition of emergence, Pluto was finally kicked out of the ranks of the planet), previously thought Pluto satellites "Charon" and a temporary number "2003ub313" (Xena) objects. Second is Proxima Centauri, the light it emits 4.22 years to reach Earth needs, sunny moonless night, in a certain place most people can see with the naked eye is about more than 3000 stars. The aid of a telescope, you can see hundreds of thousands or even hundreds of one million or more. Estimate the galaxy of stars around a, two hundred billion. Stellar does not move, just because it is too far away from us, without the aid of special tools and methodologies, change is difficult to find their position in the sky, so the ancient people refer to them as stationary stars, called stellar. Stellar also has its own life history, from their birth, growth to aging and eventually dying. They are different sizes, different colors, the evolution of the course are not the same. Contact Stellar and life not only in it provides light and heat. In fact the process of heavy atoms outbreak of planets and living matter is that at the end of life occurred in some stellar created.
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Distance
The most basic method of measuring stellar distances are trigonometric parallax method, first measured the Earth's orbit semi-major axis of the star at the opening angle (called the annual parallax), through simple arithmetic, can be calculated from the star. This is the most direct method of measuring the distance. But for most stellar to say, the opening angle is too small to measure accurately. So measuring stellar distances often use indirect methods, such as spectroscopic parallax method, cluster parallax method, statistical parallax method and by the Cepheid period-luminosity relation to determine the parallax, etc. (see distance objects). These methods are based on the indirect method based on trigonometric parallax.
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Magnitude
Stellar brightness magnitude used to represent. The brighter the star, magnitude smaller. On Earth measured magnitude called apparent magnitude; imputed to 10 seconds from Earth at the magnitude of the gap is called the absolute magnitude. Different bands using the same star-sensitive detection element of the measured magnitude is generally not equal. One of the most common magnitude system is u (UV) b (blue), v (yellow) color system (see Metering Systems' "class = link> metering system); b and v close to photographic magnitude and visual magnitude. difference between the two is commonly used color index. sun v = -26.74, absolutely visual magnitude m = +4.83, etc., color index bv = 0.63, ub = 0.12. could be determined by the color rendering index color temperature.
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Temperature
Stellar surface temperature is generally used to indicate the effective temperature, which is equal to the same diameter, the same total absolute blackbody radiation temperature. Stellar spectral energy distribution and effective temperature related, it can be _set_ o, b, a, f, g, k, m, such as spectral type (also called temperature type) stars of the same temperature, the greater the volume, the total radiation flow (ie luminosity) the greater the absolute magnitude smaller. Stellar luminosity class can be divided into Ⅰ, Ⅱ, Ⅲ, Ⅳ, Ⅴ, Ⅵ, Ⅶ, in turn called super star, bright star, superstar, Asian superstar, main-sequence star (or dwarf), sub-dwarf, the white dwarf. The sun's spectral type g2v, the color yellow, the effective temperature of about 5,770 k. a0v type stars color index average is zero, the temperature is about 10,000 k. Effective surface temperature of the star by thousands of degrees early o the tens of thousands of degrees to late m type, vary widely.
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Size
True stellar diameter and the distance can be calculated according to the star's apparent diameter (angular diameter). Common interferometer or lunar occultation method can detect small angular diameter of the star 0001, a smaller star is not easy to measure accurately, with the distance measurement error, so really reliable stellar diameter is small. According eclipsing binary orbit data and spectroscopic binary, but also draw some stellar diameter. For some stars, but also according to the absolute magnitude and effective temperature to calculate its true diameter. Obtained by various methods different stellar diameters, some as small as a few kilometers magnitude, some as large as 10 kilometers or more. The size of the star is also a great difference, some giants, some dwarf. Earth's diameter is about 13,000 km, the diameter of the sun is 109 times that of Earth. Superstar is the biggest star in the world in the head, their large diameter than the sun tens to hundreds of times. Supergiant even greater, red supergiant Antares (ie day mortgage holder α) is 600 times the diameter of the sun; red supergiant Betelgeuse (ie Orion α) is 900 times the diameter of the sun, if it is at on the position of the sun, then it is almost the size of Jupiter can pack into it. They are also not the greatest, vv Cephei is a binary star, it's a main star is 1600 times the diameter of the sun; 1800 times hr237 diameter of the sun. There is a column called a binary star, whose companion is larger than the main star is 2000-3000 times the diameter of the sun. These are giant and supergiant stars in the world of giants. Watching the stars in the world of giants, let us look at them among the dwarf. Among the stars of the world, the sun is a medium size, smaller than the sun, the stars, there are many, one of the most prominent white dwarfs and neutron stars to the number of. White dwarf only a few thousand kilometers in diameter, and the Earth almost even smaller neutron star, which is only about 20 kilometers in diameter, white dwarfs and neutron stars are stars in the world of gnomes. We know the volume of a cube of the radius of the sphere. If you take the volume to compare, then a column mentioned above should large over nine billion times more than the sun, while the neutron star must hundreds trillions of times smaller than the sun. Thus, the difference between the giant and dwarf how poor.
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Quality
Only special binary system to measure the quality, the quality is generally only be estimated based on stellar mass-luminosity relation and other methods. Stellar mass has been measured between a few percent to about 120 times the mass of the sun, but the quality of most of the stars between 0.1 and 10 solar mass star density can be calculated according to the diameter and mass, density magnitude between about 10 g / cm (red supergiant) to 10 to 10 g / cm (neutron stars) between. Atmospheric pressure and the stellar surface electron can be determined by spectral analysis. Neutral and ionized line intensity ratio of elements, not only with the temperature and abundance of the elements, but also on closely related to the electronic pressure. Between the electron pressure and gas pressure with a fixed relationship, both of which depend on the stellar surface gravity, and thus have the same luminosity close relationship (see stellar atmosphere theory). According to stellar spectra lines Zeeman splitting (see Zeeman effect) circularly polarized situation within a certain band or a continuous spectrum can be measured stellar magnetic field. Universal solar surface magnetic field is weak, only about 1 to 2 gauss, and some stellar magnetic field is strong, can reach tens of thousands of gauss. White dwarfs and neutron stars have a stronger magnetic field.
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Chemical composition
And laboratory spectroscopy on the ground, we also stellar spectra can be analyzed in order to determine the content of various stellar atmosphere to form lines of elements, of course, the situation on the ground is much more complex than is generally spectroscopy. Experimental results show that over the years, the normal stellar atmosphere atmospheric chemical composition and the sun almost. By mass, up to a hydrogen, helium, followed by the remaining sequence is substantially oxygen content, carbon, nitrogen, neon, silicon, magnesium, iron, and sulfur. But there are also a part of the chemical composition of stellar atmospheres with different solar atmosphere, such as Wolf - Rayet star, there is carbon-rich and nitrogen-rich points (ie, carbon and nitrogen sequence order of the points) and a star in the wire Type Special Star, several metal elements and lines of transuranic elements is particularly strong. However, this can be attributed to higher levels of certain elements, or a problem. Theoretical analysis shows that in the process of evolution, the chemical composition of stellar internal thermonuclear reactions will change as the process gradually changed, the content of heavy elements will be more and more, however, the chemical composition of stellar atmosphere is generally smaller changes .
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Changes in the physical properties of
Observations found that the physical characteristics of some stellar luminosity, spectral and magnetic fields are changing semi-regular or irregular cycles occur over time, and. This star is called variable stars. Variable stars are divided into two categories: one is due to changes in the geometry or the star's own special reasons, such as the geometric position between several celestial occurrence caused by the geometric variable star; One is due to the physical processes inside the star itself caused physical variable star . Geometric variable star, the most familiar are the two stars orbiting each other (and sometimes gas ring or gas disk participation) thereby causing darkening phenomenon eclipsing variable (instant binary). The light intensity changes over time, "light curve", they can be divided into Algol-type, Lyra β (Sheliak) type and Ursa w type three geometric variable stars are also included in the ellipsoid variable star (due to their own elliptical spherical, brightness variation is due to changes in the observer can see when the light-emitting area caused by rotation), Nebula variable star (located some of the stellar nebulae or after, because the nebula moves, formed absorbance change brightness changes) and so on. Tilt rotor model can be used to explain the magnetic variable star, the geometry column should also be classified as a variable star. Physical variable, according to the physical mechanism becomes light, divided into pulsating variable stars and eruptive variable types. Pulsating variable stars dimmer reason: After a long stellar main sequence stage later (see HR diagram), its own atmosphere or non-occurrence of periodic expansion and contraction, causing pulsation of luminosity variations. Theoretical calculations show that the stellar pulsation period is inversely proportional to the square root of the density. Therefore, those repeating cycle of hundreds or thousands of days of late-type irregular variable star, semiregular variable star and long-period variable stars are huge and the volume density of small late-type supergiant star or cycle between about 1 to 50 days classical Cepheids and cycle around 0.05 to 1.5 days between Lyra rr-type variable stars (also known as cluster variable stars), are the two most important pulsating variable stars. Observations showed that the former absolute magnitude smaller with the growth cycle (which is the relationship between density and cycle to adapt), which can be accurately measured by changes in their light cycle Deriving from where they themselves and their stellar group So Cepheids have universe "Lighthouse" or "hylocereus" said. Lyra rr-type variable stars have hylocereus role. There are cycles shorter than 0.3 days of pulsating variable stars (including '"class = link> Shield Block type variable stars, Vela ai-type variable stars and type variable stars'" class = link> Cephei type variable magnitude star), their atmosphere into several layers, each layer in a different form of pulsation cycles and, thus, its luminosity variation is one of several periodic variation of laminated, a large change in shape of the light curve, the light changed, as there are differences with the velocity curve of the relationship . Scutum δ-type variable stars and Vela ai-type variable star quality may be smaller, denser stars, Cepheus β-type variable stars belonging to high temperatures or sub-giant star category. Outbreak of variable stars can be divided according to the size of the outbreak of supernova star, dwarf novae, nova, and other types of Supernova. Will increase the brightness of supernovae billions of times within a very short period of time, and then in a few months to get a year or two very faint. Now, most people think it is to late stellar evolution phenomenon. The external shell supernova outward expansion to thousands or even tens of thousands of kilometers per second, the speed, and gradually expand to form a thin nebula; internal compression due to the formation of extreme density is very large objects like neutron stars. Galactic supernova is the most famous Chinese Song Dynasty (AD 1054) in Taurus discovered "days off guest star." You can now see the famous Crab Nebula in the area, the center has a period of about 33 milliseconds pulsar. Generally believed that pulsars are rapidly spinning neutron stars. Star in the visible band luminosity within a few days will suddenly enhanced magnitude of about 9 or more, then gradually reinstate a number of years. August 1975 found at Cygnus star is known so far the biggest one light change. Spectral observations show nova shells from 500 to 2,000 kilometers per second, the speed of expansion outward. Generally, only the outbreak of shell supernova explosion, the mass loss is only about one-thousandth of the total mass, and therefore not enough to make a qualitative change in the star. Some outbreaks of variable stars will make a considerable scale outbreak again called recurrent nova. Dwarf nova and nova variable star luminosity changes similar to Nova, but ranged only from 2 to 6 magnitude, shiny cycle is much shorter. They are mostly one child star binaries, so many people tend to view this kind of outbreak of a variable star in the binary accretion process caused by substances. Supernova is among some of luminosity in a few seconds to a few minutes but quickly reinstated sudden brightening some very irregular variable star fast. They are considered some of the pre-main sequence star low temperatures. There is also a Corona Borealis r type variable stars, their luminosity and star contrary, will quickly darken suddenly a few weeks, etc., and then slowly rises to its original brightness. Observations show that they are some of the carbon-rich stars. Atmospheric carbon dust particles sudden large increase, resulting in their luminosity suddenly dimmed, and thus it was also their explosive variable star called carbon. With the development of technology to expand the observation and observation band, also found there is a change, such as radio band radio variable stars and x-ray x-ray radiation flow changes of variable stars.
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Stellar Structure
Based on actual observation and spectroscopy, we can understand the basic structure of the stellar atmosphere. Generally considered part of the star, the outermost layer has a density similar to high-temperature star shaped corona crown. It is often related with the stellar wind. Some stars have been found to produce some of the emission lines in the chromosphere star crown, its inner atmosphere absorbs radiation more continuous high temperature gas formed inner absorption lines. People sometimes this atmospheric layer called the anti-change layer, while the high temperature layer is called the continuous spectrum of light emitted ball. In fact, the process of the formation of stellar radiation shows this layer is quite thick ball of light which are emitted and absorbed various stratification. Ball of light and anti-change layer can not be completely separated. Solar-type stars in the ball of light, there is an average of about one-tenth of the radius or thicker troposphere. Inside the main sequence stars and under the main sequence stars, the position is very different from the troposphere. Energy transfer in the photosphere dominated by radiation, convection in the troposphere dominated places. For the photosphere and tropospheric, we often use a more detailed study based on the model of physical properties and chemical composition of the actual measured build up. We can see from the basic assumption of hydrostatic equilibrium and thermodynamic equilibrium departure, to establish certain relationships to solve the pressure of stars in different regions, temperature, density, opacity, production rate, and chemical composition. In the center of the star, the temperature can be as high as several million degrees or even hundreds of millions of degrees, depending on the stage of the basic parameters and the evolution of stars may be. There can be a different response capacity. Stars are generally considered by the nebula condensed made before the main sequence stars due to temperature is not high enough thermonuclear reaction occurs, can only rely on gravitational contraction capacity. After entering the main sequence, the core temperature of up to 700 million degrees, began to gather hydrogen becomes helium thermonuclear reaction. This process is very long, is the longest stage of stellar life. After the hydrogen combustion is complete, the stellar interior contraction, external expansion, evolved into a low surface temperature and bulky red giant and pulsation may occur. Those degrees internal temperature rises to a hundred million stars, helium, carbon cycle began. In the process of evolution, stellar temperature and luminosity variations according to certain rules, so a certain track on the HR diagram. Finally, part of the supernova explosions of stars, gas shells flew core compressed into a dense neutron star and a class tend to "death" (see the formation and evolution of stars).
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恒星的演化
Released 26.7mev energy consumption to the stellar heating and light, the main source for the star.
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Stellar spectral classification
Early 20th century, Harvard College Observatory has carried on 500,000 stellar spectral studies. And stellar spectral lines according to their appearance in the case classified. They also found associated with the color, i.e., blue and "o", blue-white type "b", the white type "a", yellow-white and "f" yellow "g" type, orange " k "type, red" main types m "type. In fact, this is a stellar surface temperature sequence, from tens of thousands of degrees to 2-3 thousand degrees o-m-type. Danish astronomer Hertzsprung and the American astronomer Russell, according to the relationship stellar spectral type and luminosity, built the famous "spectrum - luminosity diagram", also known as "He - Luo" Fig. Most of the distribution of stars in the upper left to the lower right from the diagonal line, called the main sequence, are dwarfs. There are other super star, bright star, superstar, superstar Asia, Asia and other types of dwarf stars and white dwarfs, and the different types of shows they have different luminosity. He - Luo chart is one of the important means to study stellar. It not only shows the characteristics of various types of stars, but also reflects the evolution of stars. In the spectral classification of stars, o, b, a type called "early-type stars"; f and g type called "intermediate spectral type"; k and m-type called "late-type stars." The late 1990s, astronomers across the m-type stellar spectral classification extended to the lower temperature, the first l proposed a new type, and then again raised the temperature lower than the l-type spectral classification t type.
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Distance
Stellar magnitudes vary greatly, and there certainly has the star itself luminous intensity of reasons, but left us near and far distance also plays a significant role. The most basic method of measuring stellar distances are trigonometric parallax method, this method is mainly used to measure the distance from the star closer, as follows, first measured the Earth's orbit semi-major axis of the star at the opening angle (called the annual parallax), then after simple arithmetic, you can find the distance of the star. This is the most direct method of measuring the distance. In the sixteenth century, Copernicus published his heliocentric then, many astronomers trying to determine the distance of stars, but their values are due to the small and observation accuracy is not high time without success. Until the latter half of the 1830s was a success. However, for most stars to say, the opening angle is too small to measure accurately. So measuring stellar distances often use indirect methods, such as spectroscopic parallax method, cluster parallax method, statistical parallax method and by the Cepheid period-luminosity relation to determine the parallax, and so on. These methods are based on the indirect method based on trigonometric parallax. Since the 1920s, many astronomers to carry out work in this area, to the early 1990s, has more than 8,000 stars in the distance is measured by the photographic method. In the mid-1990s, relying on space astrometry "Hipparcos" satellite to be successful, in about three years time, with very high accuracy measurement of distances 100,000 stars. Distance from the star, if expressed in kilometers, numbers too great for convenience, usually light-years as a unit. 1 light-year is the distance light through the year. The speed of light in vacuum is 30 million meters per second, multiply the number of seconds a year, get a light-year is equal to about 9.46 trillion kilometers.
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Stellar spectral classification
Stellar classification is based on spectral and photometric binary classification carried out. In popular simplified classification, the former distinguished by the color of the star, while the latter is broadly divided into "superstar" and "dwarf", such as the Sun is a "yellow dwarf", the common name as well as "blue star" and " red giant "and so on. According to Wien's law, the color of the star has a direct relationship with the temperature. So the nature of stellar astronomers can learn from the stellar spectra. Therefore, astronomers began to absorption lines of stellar spectra according to the spectral type of the star classification since the 19th century. Astrophysics is thus developed. Based on stellar spectra of stars from the hottest type O, to temperatures as low as molecules can exist in the M-type stellar atmosphere can be divided into several types. The most important types, you can use "Oh, Be A Fine Girl, Kiss Me" (also the "girl" to "guy") phrase in English to memory (there are many other forms of formulas memories), various There are also various rare special spectral classification, which is more common L and T, suitable for smaller and cooler than the M-mass stars and brown dwarfs. Each type of high temperature to low temperature in order to mark the figures 0-9, subdivided 10 small classes. This classification is quite consistent with the high and low temperature, but no stars are classified into the highest temperature O0 and O1. Surface temperature of the color spectrum O 30,000 - 60,000 K Blue B 10,000 - 30,000 K blue A 7,500 - 10,000 K White F 6,000 - 7,500 K white and yellow G 5,000 - 6,000 K yellow (sun of this type) K 3,500 - 5,000 K orange M 2,000 - 3,500 K Red On the other hand, there is a star with "luminosity effect", which corresponds to the size of a two-dimensional classification of stars, from 0 (supergiant) through III (star) to V (dwarfs) and VII (white dwarfs). Most stars begin with ordinary stellar hydrogen burning, which is the main sequence stars. When the spectrum corresponding to the absolute magnitude of the HR diagram plotted, these stars are distributed in a diagonal line within a very narrow range. Type the Sun is G2V (yellow dwarf), particle size and temperature are very ordinary star. The sun was as a typical sample of stars, not because it is very special, because it is our nearest star, and many of the features of other stars in the sun can be combined as a unit comparison.
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Stellar motion
All things in the world are in motion, stars in the sky, though seemingly constant does not move, in fact, it also has its own movement. Because of the speed and direction of movement is not the same in different stellar, their relative positions to each other will change in the sky, known as the star of this change on their own. Among the star throughout the day, including those very dark stars, including invisible, self-fastest Barnard's star, reaching an annual 10.31 arcseconds (1 arcsecond is one of 3600 points on the circumference of a degree). General stellar own much smaller, the vast majority of less than 1 arc sec. The size of the star itself does not really reflect the size of stellar velocity. The same velocity, distance would seem very slow, but it looks from the past quickly. Because Barnard Star left us very close, less than 6 light-years, but so true velocity 88 km / s. Reflects only its own stellar stellar motion in the direction perpendicular to our line of sight, called the tangential velocity. Star along our line of sight in the direction of movement also, the speed of this movement is called radial velocity. Barnard's star radial velocity is - 108 km / s (negative radial velocity close to us that, while a positive radial velocity indicates away from us). Some stars in velocity space should be tangential velocity and radial velocity of the synthesis rate for Barnard's star, its speed is 139 km / s. Spatial movement of the stars, consists of three parts. The first is the star in a circular motion around the galactic center, which is a reflection of galactic rotation. The second is a reflection of the sun involved in galactic rotation movement. After deducting reflect these two movements, it really is the star of the sport itself, known as the star of the move.
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Spatial distribution
In addition to individual stars, binary star system can be two or more stars gravitationally bound in orbit around each other, the most common binary star system is a binary star, but three or more star systems have been found. And because the reason you want a stable orbit, these binary star systems often form the Star class rail system. There are also larger, known as cluster group: ranging from only a few stellar co-stars, the most massive with hundreds of thousands of stars, called globular clusters in the group. Star system is a long time in the gravitational field under the constraint of a particular group of stars, often by huge O and B stars form, and 80% of stars are binary star system is a multiple star system. But part of the star alone because of the smaller stellar objects were found to be increased, only 25% of red dwarfs are found to have companions. Because 85% of the stars are red dwarfs, so the majority of stars in the Milky Way are separate. Distribution of stars in the universe is not uniform, and usually with the interstellar gas, dust in galaxies together. A typical galaxy has hundreds of billions of stars, and then the number of galaxies in the observable universe is also more than one hundred billion (1011). I believe that the past exists only in galaxies of stars, but in intergalactic space has also been found in stars. Astronomers estimate there are at least 700 universe Gai (7 × 1022) stars. In addition to the Sun, the Earth's closest star is Proxima Centauri star distance is 39.9 trillion (1012) kilometers, or 4.2 light-years. Light from Proxima Centauri star to 4.2 years to reach Earth. On the space shuttle orbiting the Earth orbit speed of about 8 km / sec (about 30,000 kilometers per hour), you need 150,000 years to arrive there. Like distance, including the neighboring regions of the solar system, the galaxy disk is typical. In the center of the galaxy and globular clusters, the distance will be much closer to the star, and the distance of the halo stars are more distant. Since relative to the center, from the galaxy of stars is very open, so the stars collide with each other is very rare. But in the center of globular clusters or galaxies, stellar collisions are very common. Such collisions will form blue stragglers, these abnormal clusters of stars than in the same sequence with the same stellar luminosity of the main has a higher surface temperature. The distance between the very distant stars, astronomy general use light years to measure the distance between stars. The determination of the distance can be measured by annual parallax method, cluster parallax method, mechanical parallax method, Cepheid method.
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Naming a star
East Every star should give it a name, to be able to facilitate the study and identification. From the Warring States period in China has been named to the naked eye can distinguish the stars or to which it is named in star officer, such as days off Star, North River, second; named or noted in the legend, such as Vega (Vega), Altair (Altair II ), Canopus, etc.; Ershibasu arrangement or pursuant to the order named, such as Antares second, constitutes a less rigorous independent system. West West, the 1603 German amateur astronomer Bayer suggested that each constellation of stars in order from light to dark, with the name of the constellation with a Greek alphabetical order said. For example Orion α (Betelgeuse), Orion β (Rigel) (β fact brighter than Orion Orion α). If the number of stars in a constellation of more than 24 Greek letters, then continue using the lowercase alphabet (a, b, c ...), still less than the re-use uppercase Latin alphabet (A, B, C. ..). Britain's first observatory was founded long 佛兰斯蒂德 digital nomenclature, will star in the constellation visible from west to east, from north to south are numbered sequentially.
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Human observation and the use of stars
Hubble Telescope Sirius and its companion photo history of human observation stellar long. Sirius in ancient Egypt to the eastern horizon appears, indicating the day of the Nile flood. Chinese Shang observations on the establishment of specialized fire officials appeared in the East, to determine the moment of beginning of the year, tied with crop planting and harvesting in the inscriptions. The Chinese Ming Dynasty navigator who then use to determine the direction of the Ninth sailing. U.S. Apollo 11 spacecraft has optical locator, use the stars to determine the location. Measuring the volume of stellar interferometry and by lunar occultation of the star as measured angular diameter, thus obtain volume. The quality of the relationship between the star Kepler's third law of free or between stellar luminosity and mass measurement. HR diagram Two important features of the star is the temperature and absolute magnitude. About 100 years ago, Denmark and the United States Norris 艾基纳 respective draws find whether there is a relationship between temperature and luminosity diagram, this diagram is called the HR diagram, or H-R diagram. In the HR diagram, most stars form a diagonal area called a main sequence in astronomy. In the main sequence, the absolute magnitude of the star increases, its surface temperature increases. More than 90% of the stars belong to the main sequence, the Sun is also the main sequence of one. Giants and supergiants in the right side of the H-R diagram of far higher position. Although the high surface temperature of the white dwarf, but the brightness is not, so they are only at the bottom of the graph
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The song "stellar"
There are a Fahrenheit "Jump! Fried Rice" in the song called "stellar" sounds good yo! Lyrics Fahrenheit - Stellar Chorus: Step by step, like rotating stellar wind does not let go Because you are in my chest polished dream Day by day, never relax like a star blinking heartbeat I believe the future will be my future Jiro: Your smile across my heart arteries like matches Shape suddenly appeared in front of my exploration of dreams Wu Zun: I do not understand everything as simple as hands clasped But I was able to determine what has been burning up RAP (Jiro): You look like an angel I dim light to release the breath of life Perhaps you have long forgotten extraordinary encounter For me, it was like the only miracle The former holding a dream in the corner of my daze If you can wake up because of a laugh and Do not hesitate to believe that today There you and I will be the brightest star Chorus: Step by step, like rotating stellar wind does not let go Because you are in my chest polished dream Day by day, never relax like a star blinking heartbeat I believe that in the future you will be proud of my existence Aaron: Every word you said firefly light This is all in my side for me to illuminate farther ahead Calvin: We are not afraid to bend all the way to turn around at the terminal too More able to enjoy the journey more exciting carnival storm RAP (Jiro): You look like an angel I dim light to release the breath of life Perhaps you have long forgotten extraordinary encounter For me, it was like the only miracle The former holding a dream in the corner of my daze If you can wake up because of a laugh and Do not hesitate to believe that today There you and I will be the brightest star Chorus: Step by step, like rotating stellar wind does not let go Because you dream polish on my chest Day by day, never relax like a star blinking heartbeat I believe that in the future you will be proud of my existence Step by step, like rotating stellar wind does not let go Because you are in my chest polish dream day by day like blinking stars Heartbeat never relax I believe that in the future you will be proud of my existence
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恒星亮度排行表
18 Fomalhaut Fomalhaut Southern Fish Block 1.16 22
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Encyclopedia of Astronomy
Starry sky, except for a few a few planets, the vast majority are stellar. Stellar is composed of hot gaseous material can own heat, glowing spherical or near spherical objects, our sun is a star among these are neither too big nor too small, neither too bright nor too dark for a very ordinary members. Stellar called "constant" is actually not eternal does not move, just because in a relatively short period of time can not see it changing positions, hence the name. Appear to be normal stellar world colorful variety. Sunny moonless night, looked carefully observe closely, you will find all the bright stars are not the same, some of them glorious, gorgeous, some looming; All the stars are not the same color, blue and some of them have The white, some yellow, and redness. According to their photometric points, there is a large luminosity star, super star, there is a small dwarf luminosity. According to their color points, there are Red Star, Yellow Star, White Star, Blue Star. According to their spectral type stars, there are O, B, A, F, G, K, M and other various types of stars. Points according to their brightness variations, as well as variable stars, Supernova, novae, supernovae, and so on. Total stellar day naked eye can see over 6000, but if you use a telescope to see that the number of stars more difficult to count. We use a 10cm diameter small telescope can see the dark to about 10, such as a star, a total of about three hundred thousand stars. There is now the world's largest telescope help with the naked eye can see stars such as dark to 22 a day, you can see at least two billion stars; If the photographic method, you can shoot into the dark to 25 other stars, and that star The number should double it. Our galaxy contains a total of about 200 billion stars. Many stars, each star to understand and study the natural but also give them to take the name. In ancient times, without a telescope, relatively few people are able to see the stars, only the relatively bright star named. For example, in ancient China to give some names from the bright star Sirius, the Big Dipper, Arcturus, Cowboy, Weaver, Cepheid, etc., today, people still continue to use. Currently internationally harmonized approach is named after the star in the constellation as a "name" as a family. The constellation of stars in the brightness of the queue. The brightest is the boss, with the first letter of the Greek alphabet as the "name", the second, the third is followed by the second and third letters β and γ as a "name." And so on. Greek total of only 24, so only give 24 stars each constellation named. Greek letters in each constellation is exhausted, then using Arabic numbers continue to row. 6 stars such as Orion, Orion 56 stars, and so on. In this way, all the stars have their own name. World wide range of stellar, varied, full of wonders. Exist on some stellar material, physical state and physical processes that are not on Earth, and thus become an ideal human and huge natural physical, chemical laboratories. By understanding that people can know the secret of the universe is not only the star, but also to use the knowledge gained from the stars for life on Earth and Human Services. BRIEF: stellar spectral type.
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Encyclopedia
hengxing Star star Composed by the hot gas can be spherical or almost spherical own luminous celestial body. Nearest star from Earth is the sun. Second is Proxima Centauri, the light it emits 4.22 years to reach Earth needs, sunny moonless night, in a certain place most people can see with the naked eye about 3,000 stars. The aid of a telescope, you can see hundreds of thousands or even hundreds of one million or more. Estimate the galaxy of stars around a, two hundred billion. Stellar does not move, just because it is too far away from us, without the aid of special tools and special methods, change is difficult to find their location on the celestial sphere, and therefore the ancient people called them stars. Orion near Star The basic physical parameters describe the basic physical properties of stellar parameters of distance, brightness (apparent magnitude), luminosity (absolute magnitude), mass, diameter, temperature, pressure and magnetic field. The most basic method of measuring stellar distances are trigonometric parallax method, first measured the Earth's orbit semi-major axis of the star at the opening angle (called the annual parallax), through simple arithmetic, can be calculated from the star. This is the most direct method of measuring the distance. But for most stellar to say, the opening angle is too small to measure accurately. So measuring stellar distances often use indirect methods, such as spectroscopic parallax method, cluster parallax method, statistical parallax method and by the Cepheid period-luminosity relation to determine the parallax, etc. (see distance objects). These methods are based on the indirect method based on trigonometric parallax. Stellar brightness magnitude used to represent. The brighter the star, magnitude smaller. On Earth measured magnitude called apparent magnitude; imputed to 10 seconds from Earth at the magnitude of the gap is called the absolute magnitude. Different bands using the same star-sensitive detection element of the measured magnitude is generally not equal. One of the most common star systems is U (ultraviolet), B (blue), V (yellow) color system (see □ □ □ metering system); B and V, respectively, close to the photographic magnitude and visual magnitude . Difference between the two is commonly used color index. Sun's V = -26.74, absolutely visual magnitude M □ = +4.83, etc., color index BV = 0.63, UB = 0.12. Color index can be determined by the color temperature. Stellar surface temperature is generally used to indicate the effective temperature, which is equal to the same diameter, the same total absolute blackbody radiation temperature. Stellar spectral energy distribution and effective temperature related, it can be _set_ O, B, A, F, G, K, M and other spectral type (also called temperature type). Stars of the same temperature, the greater the volume, the total radiation flux (ie luminosity) the greater the absolute magnitude smaller. Stellar luminosity class can be divided into Ⅰ, Ⅱ, Ⅲ, Ⅳ, Ⅴ, Ⅵ, Ⅶ, in turn called super star, bright star, superstar, Asian superstar, main-sequence star (or dwarf), sub-dwarf, the white dwarf. The sun's spectral type G2V, the color yellow, the effective temperature of about 5,770 K. A0V type stars color index average is zero, a temperature of about 10,000 K. Effective surface temperature of the star by the tens of thousands of early O-M-type degrees to thousands of degrees late, very different. True stellar diameter and the distance can be calculated according to the star's apparent diameter (angular diameter). Common interferometer or lunar occultation method can detect small to 0 □ 001 stellar angular diameter, smaller star is not easy to measure accurately, coupled with the distance measurement error, so reliable stellar diameter not much really. According eclipsing binary orbit data and spectroscopic binary, but also draw some stellar diameter. For some stars, but also according to the absolute magnitude and effective temperature to calculate its true diameter. Obtained by various methods different stellar diameters, some as small as a few kilometers magnitude, some as large as 10 □ kilometers. Only special binary system to measure the quality, the quality is generally only be estimated based on stellar mass-luminosity relation and other methods. Stellar mass has been measured between a few percent to about 120 times the mass of the sun, but the quality of most of the stars between 0.1 and 10 solar masses. Stellar mass density can be calculated according to the diameter and density of the order of between about 10 □ g / cm between the □ 10 □ ~ 10 □ g / cm □ (neutron stars) (red supergiant). Atmospheric pressure and the stellar surface electron can be determined by spectral analysis. Neutral and ionized line intensity ratio of elements, not only with the temperature and abundance of the elements, but also on closely related to the electronic pressure. Between the electron pressure and gas pressure with a fixed relationship, both of which depend on the stellar surface gravity, and thus have the same luminosity close relationship (see stellar atmosphere theory). According to stellar spectra lines Zeeman splitting (see Zeeman effect) within a certain band or even
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English Expression
n.: star, sun, fixed star, a fixed star, a fixed star, ie one which is not a planet, any large ball in outer space that is made up of gases and gives out light, such as the sun
French Expression
n. étoile
Thesaurus
Hengxing Village
Related Phrases
astronomical
Capella
Artlessness Zhizui
a kind of puppet show typical in Taiwan featuring figures of tiny sacks topped with painted heads manipulated with hands and fingers