System
Sirius is a binary star system consisting of two white stars orbiting each other with a separation of about 20 astronomical units (3.0×109 km; 1.9×109 mi) (roughly the distance between the Sun and Uranus) and a period of 50.1 years. The brighter component, termed Sirius A, is a main-sequence star of spectral type A1V, with an estimated surface temperature of 9,940 K. Its companion, Sirius B, is a star that has already evolved off the main sequence and become a white dwarf. Currently 10,000 times less luminous in the visual spectrum, Sirius B was once the more massive of the two. The age of the system has been estimated at around 230 million years. Early in its lifespan it was thought to have been two bluish white stars orbiting each other in an elliptical orbit every 9.1 years. The system emits a higher than expected level of infrared radiation, as measured by IRAS space-based observatory. This may be an indication of dust in the system, and is considered somewhat unusual for a binary star. The Chandra X-ray Observatory image shows Sirius B outshining its bright partner as it is a brighter X-ray source.
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Famous quotes containing the word system:
“Never expect any recognition here—the system prohibits it. The cross is not affixed to the genius, no, the genius is affixed to the cross.”
—Franz Grillparzer (1791–1872)
“Some rough political choices lie ahead. Should affirmative action be retained? Should preference be given to people on the basis of income rather than race? Should the system be—and can it be—scrapped altogether?”
—David K. Shipler (b. 1942)
“UG [universal grammar] may be regarded as a characterization of the genetically determined language faculty. One may think of this faculty as a ‘language acquisition device,’ an innate component of the human mind that yields a particular language through interaction with present experience, a device that converts experience into a system of knowledge attained: knowledge of one or another language.”
—Noam Chomsky (b. 1928)