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Beta Lyrae Variables
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 Greek, cursive ; or ) is the second letter of the Greek alphabet. In the system of Greek numerals, it has a value of 2. In Ancient Greek, beta represented the voiced bilabial plosive . In Modern Greek, it represents the voiced bilabial 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 acrophony, acrophonic name of the corresponding letter in Phoenician alphabet, Phoenician, which was the common Semitic languages, Semitic word ('house', compare and ). In Greek, the name was , pronounced in Ancient Greek. It is spelled in modern monotonic orthography and pronounced . History The letter beta was derived from the Phoenician alphabet, Phoenician letter Bet (letter), beth . The letter Β had the largest number of highly divergent lo ... [...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 Binary star#Eclipsing binaries, eclipsing binaries; eclipsing contact binaries are known as W Ursae Majoris variables, after their archetype 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 and luminosity ratio. In cases where the stars are in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
