nova

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Faint star that suddenly erupts in brightness by 10,000 times or more, remains bright for a few days, and then fades away and is not seen again for very many years, if at all. Novae are believed to occur in close binary star systems, where gas from one star flows to a companion white dwarf. The gas ignites and is thrown off in an explosion at speeds of 1,500 kps/930 mps or more. Unlike a supernova, the star is not completely disrupted by the outburst. After a few weeks or months it subsides to its previous state; it may erupt many more times.

Although the name comes from the Latin ‘new’, photographic records show that such stars are not really new, but are faint stars undergoing an outburst of radiation that temporarily gives them an absolute magnitude in the range -6 to -10, at least 100,000 times brighter than the Sun. They fade away, rapidly at first and then more slowly over several years. Two or three such stars are detected in our Galaxy each year, but on average one is sufficiently close to us to become a naked-eye object only about once in ten years. Novae very similar to those appearing in our own Galaxy have also been observed in other galaxies.

The George Cross was awarded by King George VI and originally appeared in a small blue canton. The present design dates from 1964 when the islands gained independence. Effective date: 21 September 1964. >>