Apurv1999

Welcome

Welcome to Wikipedia ! And make good edits. -- Extra999 or Sawarnik (talk) 05:21, 5 November 2009 (UTC)

November 2009

Welcome to Wikipedia, and thank you for your contributions. One of the core policies of Wikipedia is that articles should always be written from a neutral point of view. A contribution you made to Delhi Public School Society appears to carry a non-neutral point of view, and your edit may have been changed or reverted to correct the problem. Please remember to observe our core policies. Thank you. --SquidSK ^(1MC•log) 13:20, 8 November 2009 (UTC)

White dwarf

A white dwarf (also known as degenerate dwarf) is a kind of small star having an extraordinary density. Its volume or size can be comparable to Earth but its mass to Sun. The name white dwarf was coined by William Luyten in 1922. It is formed when planetary nebula peels away and it is the last stage of a main-sequence or an average star (0.5 to 8 solar masses). It undergoes fusion and slowly turns reddish as it radiates energy. So it happens it turns black and forms a cool black dwarf having no energy to glow. The first white dwarf to be discovered was in the triple-star system 40 Eridani and 40 Eridani B. This triple star system also comprises of 40 Eridani A being a bright main-sequence star. And Eridani C is a red giant orbiting with 40 Eridani B. This pair was discovered by William Herschel on January 31,1783. In 1910 it was told that it is a dim star. The next one to be discovered was Sirius B. 18 white dwarfs were known by 1939. Till 1950 over a hundred were known and today over 10000. The mass of a white dwarf can range from 0.17 solar mass to 1.33 solar mass but its radius can range from 0.007 solar radius to 0.02 solar radius making it extraordinary dense. One special thing of a white dwarf is : the more massive it is, more smaller it is! White dwarfs are one of the most dense object of the universe passing only neutron star,black holes and other compact stars. When Ernst Öpik estimated the density of 40 Eridani B he found it was over 25,000 times of Sun. It was so high that he thought it is “impossible”. You may too think like this but this can be possible only if the atoms are not bounded by chemical bonds but consists of plasma with unbounded nuclei and electrons. White dwarf’s surface temperature can be as high as 150,000 K and as low as 3500 K. But most of them is between 8,000 K to 40,000 K. The coolest known white dwarf,WD 0346+246,has a temperature of 3900 K. The reason for such low temperature is because the universe‘s age is finite and so no more cooler white dwarfs have been found. When white dwarfs gets older its radiation loosens and cools down and then a black dwarf forms. Till now no black dwarfs have been found because it takes around 10 billion years to cool down that much. A white dwarf is mainly made up of carbon and oxygen and its atmosphere is made of normal (hydrogen or helium) gases. That’s why spectroscopy shows emitted lights coming from the atmosphere which is believed to be composed ofhydrogen or helium. The high surface gravity causes the lighter gases to be at the top and heavier ones to be at the bottom. A white dwarf with the surface temperature between 8,000 K and 16,000 K will have a core temperature between approximately 5,000,000 K and 20,000,000 K. The first attempt to classify white dwarf spectra appears to have been by G. P. Kuiper in 1941, and various classification schemes have been proposed and used since then. The system currently in use was introduced by Edward M. Sion and others.

Diamond star – A conclusion is consistent with the 2004 discovery of a cooling white dwarf star that appears to have a solid diamond core 4000 kilometers across! The cosmic diamond is a chunk of crystallized carbon, 4,000 km across, some 50 light-years from the Earth in the constellation Centaurus. Astronomers have named it Lucy after the Beatles song, Lucy in the Sky with Diamonds. With this it has been found that most of the white dwarfs,main–sequence stars and red giant will once have a core made of diamond. --Extra999 (talk) 21:16, 2 December (UTC)

Hello

How are you? Thanks for contributing to Wikipedia. I am Sawarnik, your old friend, --Extra999 (Contact ^me + _contribs) 17:33, 12 April 2010 (UTC)

Reply

Yes my phone no. : I will not right this straight, since it is accessible to all. It's great to see you back. Please give your email address and reply as soon as possible. --Extra 999 (Contact ^me + _contribs) 15:23, 18 July 2011 (UTC)

Check your inbox. --Extra 999 (Contact ^me + _contribs) 11:52, 20 July 2011 (UTC)

March 2012

Please refrain from making unconstructive edits to Wikipedia, as you did at Anil Kumble. Your edits appear to constitute vandalism and have been reverted or removed. If you would like to experiment, please use the sandbox. Thank you. —Vensatry _{(Ping me)} 05:59, 23 March 2012 (UTC)