Bayliss effect - Revision history

en>WhatamIdoing: Name in first sentence

2014-08-17T06:37:51Z

Name in first sentence

← Older revision		Revision as of 08:37, 17 August 2014
Line 1:		Line 1:
	~~{{For\|combustion of lithium\|combustion}}~~		The name of the author is Jayson. Her family lives in Ohio but her spouse desires them to move. The preferred pastime for him and his children is to perform lacross and he would never give it up. Invoicing is what I do.<br><br>my site - best psychic ([http://chorokdeul.co.kr/index.php?document_srl=324263&mid=customer21 http://chorokdeul.co.kr/index.php?document_srl=324263&mid=customer21])

	[[Lithium]] is generally present in [[brown dwarf]]s and not in low-mass stars. Stars, which by definition must achieve the high temperature (2.5 × 10<sup>6</sup> K) necessary for fusing [[hydrogen]], rapidly deplete their lithium. This occurs by a collision of [[lithium-7]] and a [[proton]] producing two [[helium-4]] nuclei. The ~~temperature necessary for this reaction is just below the temperature necessary for [[hydrogen fusion]]. Convection in low-mass stars ensures that lithium in the whole volume~~ of the ~~star~~ is ~~depleted~~. ~~Therefore, the presence of the lithium [[spectral line\|line]]~~ in ~~a candidate brown dwarf's spectrum is a strong indicator that it is indeed substellar~~.

	From a study of lithium abundances in 53 [[T Tauri star]]s, it has been found that lithium depletion varies strongly with size, suggesting that lithium burning by the [[Proton-proton chain reaction\|P-P chain]], during the last highly convective and unstable stages during the [[pre–main sequence star\|pre–main sequence]] later phase of the [[Hayashi track\|Hayashi contraction]] may be one of the main sources of energy for T Tauri stars. Rapid rotation tends to ~~improve mixing~~ and ~~increase the transport of lithium into deeper layers where~~ it ~~is destroyed. T Tauri stars generally increase their rotation rates as they age, through contraction and spin-~~up~~, as they conserve angular momentum~~. ~~This causes an increased rate of lithium loss with age. Lithium burning will also increase with higher temperatures and mass, and will last for at most a little over 100 million years~~.

	~~The P-P chain for lithium burning is as follows~~

	<~~!-- Autogenerated using Phykiformulae 0.12 [[User:SkyLined#Phykiformulae]]~~
	~~p+ + Li-6 -~~> ~~Li-7~~
	~~p+ + Li-7 -~~> Be-8 (~~unstable)~~
	~~_ _ Be-8 -> 2He-4 +_energy~~
	~~-->~~:~~{\| border="0"~~
	~~\|- style="height:2em;"~~
	~~\|{{Subatomic particle\|link=yes\|Proton}} \|\|+ \|\|{{Nuclide\|Link\|lithium\|6}} \|\|→ \|\|{{Nuclide\|Link\|beryllium\|7}}\|\| \|\|(unstable)~~
	~~\|- style="height:2em;"~~
	~~\|{{Nuclide\|Link\|beryllium\|7}} \|\|+ \|\|{{Subatomic particle\|link=yes\|Electron}} \|\|→ \|\|{{Nuclide\|Link\|lithium\|7}} \|\|+ {{Subatomic particle\|link=yes\|neutrino}}~~
	~~\|- style="height:2em;"~~
	~~\|{{Subatomic particle\|link~~=~~yes\|Proton}} \|\|+ \|\|{{Nuclide\|Link\|lithium\|7}} \|\|→ \|\|{{Nuclide\|Link\|beryllium\|8}} \|\|~~&~~nbsp;\|\|(unstable)~~
	~~\|- style~~=~~"height~~:~~2em;"~~
	~~\| \|\| \|\|{{Nuclide\|Link\|beryllium\|8}} \|\|→ \|\|2 {{Nuclide\|Link\|helium\|4}} \|\|+ energy~~
	\|}

	~~It will not occur in stars less than sixty times the mass of Jupiter. In this way, the rate of lithium depletion can be used to calculate the age of the star.~~

	~~The use of lithium to distinguish candidate brown dwarfs from low-mass stars is commonly referred to as the '''lithium test''', and was pioneered by [[Rafael Rebolo]] and colleagues~~. ~~Heavier stars like our sun can retain lithium in their outer atmospheres, which never get hot enough for lithium depletion, but those are distinguishable from brown dwarfs by their size~~. Brown dwarfs at the high end of their mass range can be hot enough to deplete their lithium when they are young. Dwarfs of mass greater than 65 <math>M_J</math> can burn off their lithium by the time they are half a billion years old<sup>[Kulkarni]</~~sup>, thus this test is not perfect~~.

	~~{{Nuclear_processes}}~~

	~~[[Category:Nuclear fusion]]~~
	~~[[Category:Lithium]~~]

en>Addbot: Bot: Migrating 4 interwiki links, now provided by Wikidata on d:q407396

2013-03-01T12:59:37Z

Bot: Migrating 4 interwiki links, now provided by Wikidata on d:q407396

← Older revision		Revision as of 14:59, 1 March 2013
Line 1:		Line 1:
	~~I would like to introduce myself to you~~, ~~I am Andrew~~ and ~~my spouse doesn't like it at all~~. ~~Office supervising~~ is ~~my occupation~~. ~~For many years he~~'s ~~been residing in Alaska and he doesn't strategy on altering~~ it. ~~One~~ of the ~~extremely best things in~~ the ~~globe good~~ [~~http://findyourflirt~~.~~net/index~~.~~php?m~~=~~member_profile~~&p=~~profile~~&id=~~117823 clairvoyant psychic]~~ (~~[http~~:~~//fashionlinked~~.~~com/index~~.~~php?do=/profile~~-~~13453/info/ fashionlinked~~.~~com])~~ for ~~him is performing ballet and he'll~~ be ~~starting something else along with it~~.<br><br>~~Look at my blog :~~: [~~http~~:~~//www.edmposts.com/build-a-beautiful-organic-garden-using-these-ideas/ live psychic reading~~]		{{For\|combustion of lithium\|combustion}}

			[[Lithium]] is generally present in [[brown dwarf]]s and not in low-mass stars. Stars, which by definition must achieve the high temperature (2.5 × 10<sup>6</sup> K) necessary for fusing [[hydrogen]], rapidly deplete their lithium. This occurs by a collision of [[lithium-7]] and a [[proton]] producing two [[helium-4]] nuclei. The temperature necessary for this reaction is just below the temperature necessary for [[hydrogen fusion]]. Convection in low-mass stars ensures that lithium in the whole volume of the star is depleted. Therefore, the presence of the lithium [[spectral line\|line]] in a candidate brown dwarf's spectrum is a strong indicator that it is indeed substellar.

			From a study of lithium abundances in 53 [[T Tauri star]]s, it has been found that lithium depletion varies strongly with size, suggesting that lithium burning by the [[Proton-proton chain reaction\|P-P chain]], during the last highly convective and unstable stages during the [[pre–main sequence star\|pre–main sequence]] later phase of the [[Hayashi track\|Hayashi contraction]] may be one of the main sources of energy for T Tauri stars. Rapid rotation tends to improve mixing and increase the transport of lithium into deeper layers where it is destroyed. T Tauri stars generally increase their rotation rates as they age, through contraction and spin-up, as they conserve angular momentum. This causes an increased rate of lithium loss with age. Lithium burning will also increase with higher temperatures and mass, and will last for at most a little over 100 million years.

			The P-P chain for lithium burning is as follows

			<!-- Autogenerated using Phykiformulae 0.12 [[User:SkyLined#Phykiformulae]]
			p+ + Li-6 -> Li-7
			p+ + Li-7 -> Be-8 (unstable)
			_ _ Be-8 -> 2He-4 +_energy
			-->:{\| border="0"
			\|- style="height:2em;"
			\|{{Subatomic particle\|link=yes\|Proton}} \|\|+ \|\|{{Nuclide\|Link\|lithium\|6}} \|\|→ \|\|{{Nuclide\|Link\|beryllium\|7}}\|\| \|\|(unstable)
			\|- style="height:2em;"
			\|{{Nuclide\|Link\|beryllium\|7}} \|\|+ \|\|{{Subatomic particle\|link=yes\|Electron}} \|\|→ \|\|{{Nuclide\|Link\|lithium\|7}} \|\|+ {{Subatomic particle\|link=yes\|neutrino}}
			\|- style="height:2em;"
			\|{{Subatomic particle\|link=yes\|Proton}} \|\|+ \|\|{{Nuclide\|Link\|lithium\|7}} \|\|→ \|\|{{Nuclide\|Link\|beryllium\|8}} \|\| \|\|(unstable)
			\|- style="height:2em;"
			\| \|\| \|\|{{Nuclide\|Link\|beryllium\|8}} \|\|→ \|\|2 {{Nuclide\|Link\|helium\|4}} \|\|+ energy
			\|}

			It will not occur in stars less than sixty times the mass of Jupiter. In this way, the rate of lithium depletion can be used to calculate the age of the star.

			The use of lithium to distinguish candidate brown dwarfs from low-mass stars is commonly referred to as the '''lithium test''', and was pioneered by [[Rafael Rebolo]] and colleagues. Heavier stars like our sun can retain lithium in their outer atmospheres, which never get hot enough for lithium depletion, but those are distinguishable from brown dwarfs by their size. Brown dwarfs at the high end of their mass range can be hot enough to deplete their lithium when they are young. Dwarfs of mass greater than 65 <math>M_J</math> can burn off their lithium by the time they are half a billion years old<sup>[Kulkarni]</sup>, thus this test is not perfect.

			{{Nuclear_processes}}

			[[Category:Nuclear fusion]]
			[[Category:Lithium]]

en>Ssaydjari at 10:22, 31 July 2012

2012-07-31T10:22:28Z

New page

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