{"id":97443,"date":"2018-03-11T10:17:59","date_gmt":"2018-03-11T10:17:59","guid":{"rendered":"https:\/\/www.deberes.net\/tesis\/sin-categoria\/accretion-onto-neutron-stars-hydrodynamics-and-nucleosynthesis\/"},"modified":"2018-03-11T10:17:59","modified_gmt":"2018-03-11T10:17:59","slug":"accretion-onto-neutron-stars-hydrodynamics-and-nucleosynthesis","status":"publish","type":"post","link":"https:\/\/www.deberes.net\/tesis\/estrellas-dobles\/accretion-onto-neutron-stars-hydrodynamics-and-nucleosynthesis\/","title":{"rendered":"Accretion onto neutron stars: hydrodynamics and nucleosynthesis"},"content":{"rendered":"<h2>Tesis doctoral de <strong> Ferm\u00edn Moreno Guzm\u00e1n <\/strong><\/h2>\n<p>In the middle of the 70s, some authors suggested that accretion of hydrogen and helium rich material  by a neutron star in a binary system, where the companion star would have low mass, could explain  thermonuclear bursts observed by the first satellites launched to the space in order to analyze the x- ray band of the electromagnetic spectrum. This phenomenon, known as type i x-ray bursts (xrb), is a  thermonuclear runaway produced by the themonuclear fusion of the accreted material in degenerated  conditions. This kind of explosion from stellar source is the most frequent in our galaxy (and the third,  after supernovae and classical novae, in terms of total output energy), because his short recurrence  period.   Due   to   the   extreme   gravitational   field   of   a   neutron   star   it   is   known   that   produced  nucleosynthesis is not ejected to the interstellar medium but forming part of the neutron star crust.  in this work we have tried, first, to study the effects of nuclear uncertainties, related to nuclear reaction  rates,   in   the   nucleosynthesis   produced   during   a   x-ray   burst,   and   second,   to   simulate   physical  properties and associated nucleosynthesis to this kind of events, through hydrodynamical models.  in order to analyze the impact of uncertainties of the nuclear reaction rates in the nucleosynthesis, and  due to the prohibitive calculation time with an hydrodinamical code, we have used a post-processing  code which we have coupled, for a given set of 10 temperatures and densities profiles, an extensive  nuclear reactions network formed by 606 isotopes and 3551 nuclear reactions, whose reaction rates  have been modified using to alternative methods.   In the  first one,  every rate has been  individually  modified, multiplying it by 0.1 and 10, calculating the final nucleosynthesis. This way, it is possible to  evaluate the impact in final nucleosynthesis individual variations in the nuclear reaction rates. Also we  have analyzed the effects in final nucleosynthesis by modifying the energy associated to each reaction  (q-value).   In   the   second   method,   nuclear   reaction   rates   have   been   modified   simultaneously,  multiplying each one by a random factor which follow a  log-normal distribution with a probability of  95.5% of being in the interval [0.1,10]. In order to analyzed this method from an statistically point of  view, the nucelosynthesis has been calculated up to 10,000 times, with a monte carlo code specifically  built   to  this thesis,   for  different  set  of   random numbers.  Obtained  results with both methods are  coincidents and show  that   for  a network  formed by 3,500  reactions approximately,  only about  60  reactions   have   an   impact   in   final   yields   greater   than   a   factor   of   2.Finally,   we   have   used   an  hydrodynamical code,  one-dimensional (spherically symmetric), lagrangian and multi-shell, to which  we have coupled a nuclear reactions network formed by 324 isotopes and 1392 reactions with the aim  of reproduce physical parameters and nucleosynthesis produced during x-ray bursts.  T o do that, we  have applied this code to different models,  analyzing the effect of spatial resolution in the accreted  shell, the metallicity of the transferred material as well as the mass of the neutron star, in the final   result. For each model, we have simulated different bursts, with energies, luminosities and recurrence  times   coincidents  with observations  and,   together  with  the nucleosynthesis,   similar   to  the  results  obtained by other authors.<\/p>\n<p>&nbsp;<\/p>\n<h3>Datos acad\u00e9micos de la tesis doctoral \u00ab<strong>Accretion onto neutron stars: hydrodynamics and nucleosynthesis<\/strong>\u00ab<\/h3>\n<ul>\n<li><strong>T\u00edtulo de la tesis:<\/strong>\u00a0 Accretion onto neutron stars: hydrodynamics and nucleosynthesis <\/li>\n<li><strong>Autor:<\/strong>\u00a0 Ferm\u00edn Moreno Guzm\u00e1n <\/li>\n<li><strong>Universidad:<\/strong>\u00a0 Polit\u00e9cnica de catalunya<\/li>\n<li><strong>Fecha de lectura de la tesis:<\/strong>\u00a0 25\/11\/2009<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<h3>Direcci\u00f3n y tribunal<\/h3>\n<ul>\n<li><strong>Director de la tesis<\/strong>\n<ul>\n<li>Jordi Jos\u00e9 Pont<\/li>\n<\/ul>\n<\/li>\n<li><strong>Tribunal<\/strong>\n<ul>\n<li>Presidente del tribunal: enrique Garc\u00eda-berro montilla <\/li>\n<li>anuj r. Parikh (vocal)<\/li>\n<li>alain Coc (vocal)<\/li>\n<li>margarida Hernanz carb\u00f3 (vocal)<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Tesis doctoral de Ferm\u00edn Moreno Guzm\u00e1n In the middle of the 70s, some authors suggested that accretion of hydrogen and [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""}},"footnotes":""},"categories":[1462,10032,92507,15596],"tags":[199673,199672,26074,199671,33967,19679],"class_list":["post-97443","post","type-post","status-publish","format-standard","hentry","category-estrellas-dobles","category-evolucion-estelar-y-diagrama-hr","category-fuentes-de-rayos-x","category-politecnica-de-catalunya","tag-alain-coc","tag-anuj-r-parikh","tag-enrique-garcia-berro-montilla","tag-fermin-moreno-guzman","tag-jordi-jose-pont","tag-margarida-hernanz-carbo"],"_links":{"self":[{"href":"https:\/\/www.deberes.net\/tesis\/wp-json\/wp\/v2\/posts\/97443","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.deberes.net\/tesis\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.deberes.net\/tesis\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.deberes.net\/tesis\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.deberes.net\/tesis\/wp-json\/wp\/v2\/comments?post=97443"}],"version-history":[{"count":0,"href":"https:\/\/www.deberes.net\/tesis\/wp-json\/wp\/v2\/posts\/97443\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.deberes.net\/tesis\/wp-json\/wp\/v2\/media?parent=97443"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.deberes.net\/tesis\/wp-json\/wp\/v2\/categories?post=97443"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.deberes.net\/tesis\/wp-json\/wp\/v2\/tags?post=97443"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}