|
Beta Lyrae Variable
Beta Lyrae variables are a class of close binary stars. Their total brightness is variable because the two component stars orbit each other, and in this orbit one component periodically passes in front of the other one, thereby blocking its light. The two component stars of Beta Lyrae systems are quite heavy (several solar masses () each) and extended (giants or supergiants). They are so close, that their shapes are heavily distorted by mutual gravitation forces: the stars have ellipsoidal shapes, and there are extensive mass flows from one component to the other. Mass flows These mass flows occur because one of the stars, in the course of its evolution, has become a giant or supergiant. Such extended stars easily lose mass, just because they are so large: gravitation at their surface is weak, so gas easily escapes (the so-called stellar wind). In close binary systems such as beta Lyrae systems, a second effect reinforces this mass loss: when a giant star swells, it may reach it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beta Lyrae-type Variable Binary Star Animation 1
Beta (, ; uppercase , lowercase , or cursive ; grc, βῆτα, bē̂ta or ell, βήτα, víta) is the second letter of the Greek alphabet. In the system of Greek numerals, it has a value of 2. In Modern Greek, it represents the voiced labiodental fricative while in borrowed words is instead commonly transcribed as μπ. Letters that arose from beta include the Roman letter and the Cyrillic letters and . Name Like the names of most other Greek letters, the name of beta was adopted from the acrophonic name of the corresponding letter in Phoenician, which was the common Semitic word ''*bait'' ('house'). In Greek, the name was ''bêta'', pronounced in Ancient Greek. It is spelled βήτα in modern monotonic orthography and pronounced . History The letter beta was derived from the Phoenician letter beth . Uses Algebraic numerals In the system of Greek numerals, beta has a value of 2. Such use is denoted by a number mark: Β′. Computing Finance Beta is used ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Contact Binary
In astronomy, a contact binary is a binary star system whose component stars are so close that they touch each other or have merged to share their gaseous envelopes. A binary system whose stars share an envelope may also be called an overcontact binary. The term "contact binary" was introduced by astronomer Gerard Kuiper in 1941. Almost all known contact binary systems are eclipsing binaries; eclipsing contact binaries are known as W Ursae Majoris variables, after their type star, W Ursae Majoris. In a contact binary, both stars have filled their Roche lobes, allowing the more massive primary component to transfer both mass and luminosity to the secondary member. As a result, the components in a contact binary often have similar effective temperatures and luminosities, regardless of their respective masses. The rate of energy transfer between the components is dependent on their mass ratio or absolute mass number and luminosity ratio. In cases where the stars are in geometri ... [...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] |
Delta Pictoris
Delta Pictoris, Latinized from δ Pictoris, is a binary star system in the southern constellation Pictor. It is visible to the naked with a combined apparent visual magnitude of 4.72. The system is located at a distance of approximately 1,300 light years from the Sun based on parallax measurements, and is drifting further away with a radial velocity of ~31 km/s. It is a runaway star system that is generating a bow shock as it moves through the interstellar medium. The binary nature of this system was discovered by R. E. Wilson in 1914, then it was found to be variable by A. W. J. Cousins in 1951. A. D. A. Thackeray published orbital elements for the pair in 1966, showing they form an eclipsing double-lined spectroscopic binary with an orbital period of 1.67 days in essentially a circular orbit. The low inclination of the orbital plane The orbital plane of a revolving body is the geometric plane in which its orbit lies. Three non-collinear ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
TU Muscae
TU Muscae, also known as HD100213, is an eclipsing binary star in the constellation Musca. Its apparent magnitude ranges from 8.17 to 8.75 over around 1.4 days. Physical description TU Muscae is a remote binary star system made up of two hot luminous blue main sequence stars of spectral types O7.5V and O9.5V, with masses 23 and 15 times that of the Sun. The stars are so close that they are in contact with each other ( overcontact binary) and are classed as a Beta Lyrae variable Beta Lyrae variables are a class of close binary stars. Their total brightness is variable because the two component stars orbit each other, and in this orbit one component periodically passes in front of the other one, thereby blocking its light ... as their light varies from earth as they eclipse each other. The spectra indicate they are hot stars, with surface temperatures of roughly 37200 and 34700 K respectively. They are both still on the main sequence of star evolution, burning their ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beta Lyrae
Beta Lyrae (β Lyrae, abbreviated Beta Lyr, β Lyr) officially named Sheliak (Arabic: الشلياق, Romanization: ash-Shiliyāq) ( IPA: ), the traditional name of the system, is a multiple star system in the constellation of Lyra. Based on parallax measurements obtained during the Hipparcos mission, it is approximately distant from the Sun. Although it appears as a single point of light to the naked eye, it actually consists of six components of apparent magnitude 14.3 or brighter. The brightest component, designated Beta Lyrae A, is itself a triple star system, consisting of an eclipsing binary pair (Aa) and a single star (Ab). The binary pair's two components are designated Beta Lyrae Aa1 and Aa2. The additional five components, designated Beta Lyrae B, C, D, E, and F, are currently considered to be single stars. Nomenclature ''β Lyrae'' ( Latinised to ''Beta Lyrae'') is the system's Bayer designation, established by Johann Bayer in his ''Uranometria'' of 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tau Canis Majoris
Tau Canis Majoris (τ CMa, τ Canis Majoris, 30 CMa) is a multiple star system in the constellation Canis Major. It is approximately 5,000 light years distant from Earth and is the brightest member of the open cluster NGC 2362 NGC 2362, also known as Caldwell 64, is an open cluster of stars in the southern constellation of Canis Major. It was discovered by the Italian court astronomer Giovanni Batista Hodierna, who published his finding in 1654. William Herschel called .... System τ Canis Majoris lies at the center of the very young open cluster NGC 2362 which contains several hundred stars. It is by far the brightest member of the cluster and the only one to have evolved away from the main sequence. A number of stars were catalogued by John Herschel as companions: component B is a 10th magnitude star 8.6 arc-seconds distant; component C is a 14th magnitude star 14.2 arc-seconds away; and component D is an 8th magnitude star at 85 arc-seconds. These stars are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
UW Canis Majoris
UW Canis Majoris is a star in the constellation Canis Major. It is classified as a Beta Lyrae eclipsing contact binary and given the variable star designation UW Canis Majoris. Its brightness varies from magnitude +4.84 to +5.33 with a period of 4.39 days. Bode had initially labelled it as Tau2 Canis Majoris, but this designation had been dropped by Gould and subsequent authors. UW Canis Majoris A is a rare blue supergiant of spectral type O7.5-8 Iab. The precise characteristics of the system are still uncertain, in part because the spectral signature of the secondary is very hard to disentangle from the spectrum of the primary and the surrounding envelope of stellar wind. A detailed spectral study by Gies et al. found that the primary had a diameter 13 times that of the Sun, while its secondary companion is a slightly cooler, less evolved and less luminous supergiant of spectral type O9.7Ib that is 10 times the Sun's diameter. According to this study, the brighte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DV Aquarii
DV Aquarii is a binary star system in the zodiac constellation of Aquarius. It has a peak apparent visual magnitude of 5.89, which is bright enough to be visible to the naked eye. The distance can be estimated from its annual parallax shift of , yielding a separation of 291 light years. This is a detached eclipsing binary system of the Beta Lyrae type. The orbital period for the system is 1.5755 days and the eccentricity is unknown and probably non-zero; the orbital inclination is estimated to be . During the primary eclipse the magnitude drops to 6.25. It descends to 6.10 with the secondary eclipse (with 6.10 being brighter than 6.25). The pair have been identified as candidate Herbig Ae/Be stars, and catalogued as A-type shell stars. A magnitude 10.8 star with the designation HD 358087 is a common proper motion companion. It is located at an angular separation of and has 78% of the Sun's mass. If it is gravitationally bound The gravitational binding ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zeta Andromedae
Zeta Andromedae (Zeta And, ζ Andromedae, ζ And) is a star system in the constellation Andromeda. It is approximately 189 light-years from Earth. Zeta Andromedae is the star's Bayer designation. It also has the Flamsteed designation 34 Andromedae and multiple other designations in stellar catalogues. Location The star's location is in the northern constellation Andromeda, in which it is the second-most southerly of the stars in this often drawn characteristic shape representing the mythical princess asterism, after η Andromedae. System The system is a spectroscopic binary whose is classified as an orange K-type giant with a mean apparent magnitude of +4.08. Due to brightness changes caused by the ellipsoidal shape of that object, the system is also an RS Canum Venaticorum-type variable star. Its brightness varies from magnitude +3.92 to +4.14 with a period of 17.77 days, and its spectrum shows strong and variable Ca II H and K ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lightyear
A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 (one million million, or billion in long scale). As defined by the International Astronomical Union (IAU), a light-year is the distance that light travels in a vacuum in one Julian year (365.25 days). Because it includes the time-measurement word " year", the term ''light-year'' is sometimes misinterpreted as a unit of time. The ''light-year'' is most often used when expressing distances to stars and other distances on a galactic scale, especially in non-specialist contexts and popular science publications. The unit most commonly used in professional astronomy is the parsec (symbol: pc, about 3.26 light-years) which derives from astrometry; it is the distance at which one astronomical unit subtends an angle of one second of arc. De ... [...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] |
