A white dwarf is a stellar core remnant composed mostly of electron- degenerate matter, supported against its own gravity only by electron degeneracy pressure. A white dwarf is very dense: in an Earth sized volume, it contains a mass comparable to the Sun. What light it radiates is from its residual heat. White dwarfs are thought to be the final evolutionary state of stars whose mass is insufficient for them to become a neutron star or black hole. This includes more than 97% of the stars in the Milky Way. After the hydrogen-fusing period of such a main- sequence star ends, it will expand to a red giant and shed its outer layers, leaving behind a core which is the white dwarf. This, very hot when it forms, cools as it radiates its energy until its material begins to crystallize into a cold black dwarf. The oldest known white dwarfs still radiate at temperatures of a few thousand kelvins, which establishes an observational limit on the maximum possible age of the universe.
Read more: <https://en.wikipedia.org/wiki/White_dwarf> _______________________________ Today's selected anniversaries: 1717: The first Grand Lodge of Freemasonry, the Premier Grand Lodge of England, was founded in London. <https://en.wikipedia.org/wiki/Premier_Grand_Lodge_of_England> 1724: On the Feast of St. John the Baptist, Bach led the first performance of Christ unser Herr zum Jordan kam, BWV 7, the third cantata of his chorale cantata cycle. <https://en.wikipedia.org/wiki/Christ_unser_Herr_zum_Jordan_kam,_BWV_7> 1943: Amid racial tensions, U.S. Army military police shot and killed a black serviceman after a confrontation at a pub in Bamber Bridge, England. <https://en.wikipedia.org/wiki/Battle_of_Bamber_Bridge> 2010: Julia Gillard was sworn in as the first female prime minister of Australia after incumbent Kevin Rudd declined to contest a leadership spill in the Labor Party. <https://en.wikipedia.org/wiki/Julia_Gillard> _____________________________ Wiktionary's word of the day: supracargo: 1. (historical) An officer on board a merchant ship who is in charge of the cargo and its sale; also, if there are two of such officers, the senior one, the other being the subcargo. 2. (obsolete) An agent or representative of a company in charge of its overseas business. <https://en.wiktionary.org/wiki/supracargo> ___________________________ Wikiquote quote of the day: Revelation, n. A famous book in which St. John the Divine concealed all that he knew. The revealing is done by the commentators, who know nothing. --Ambrose Bierce <https://en.wikiquote.org/wiki/Ambrose_Bierce> _______________________________________________ Wikipedia Daily Article mailing list. To unsubscribe write to: [email protected] Questions or comments? Contact [email protected]
