<?xml version="1.0" encoding="ISO-8859-1"?><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<front>
<journal-meta>
<journal-id>0185-1101</journal-id>
<journal-title><![CDATA[Revista mexicana de astronomía y astrofísica]]></journal-title>
<abbrev-journal-title><![CDATA[Rev. mex. astron. astrofis]]></abbrev-journal-title>
<issn>0185-1101</issn>
<publisher>
<publisher-name><![CDATA[Universidad Nacional Autónoma de México, Instituto de Astronomía]]></publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id>S0185-11012020000100003</article-id>
<article-id pub-id-type="doi">10.22201/ia.01851101p.2020.56.01.01</article-id>
<title-group>
<article-title xml:lang="en"><![CDATA[Analytical Solutions for the Dynamical Clock A+ Indicator in a Toy Model of Pure Dynamical Friction]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Pasquato]]></surname>
<given-names><![CDATA[M.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
<xref ref-type="aff" rid="Aaf"/>
</contrib>
</contrib-group>
<aff id="Af1">
<institution><![CDATA[,INAF  ]]></institution>
<addr-line><![CDATA[Padova ]]></addr-line>
<country>Italy</country>
</aff>
<aff id="Af2">
<institution><![CDATA[,INFN  ]]></institution>
<addr-line><![CDATA[Padova ]]></addr-line>
<country>Italy</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>00</month>
<year>2020</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>00</month>
<year>2020</year>
</pub-date>
<volume>56</volume>
<numero>1</numero>
<fpage>3</fpage>
<lpage>6</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_arttext&amp;pid=S0185-11012020000100003&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_abstract&amp;pid=S0185-11012020000100003&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_pdf&amp;pid=S0185-11012020000100003&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="en"><p><![CDATA[ABSTRACT Blue straggler stars are more massive than the average star in globular clusters, as they originate from the merger of two stars. Consequently, they experience dynamical friction, progressively sinking to the cluster center. Recently, several indicators of the degree of dynamical relaxation of a globular cluster have been proposed, based on the observed radial distribution of blue straggler stars. The most successful is the Alessandrini indicator, or A+ for short, which is the integral of the cumulative distribution of the blue straggler stars minus that of a lighter reference population. A+ correlates with the dynamical age of a cluster both in realistic simulations and in observations. Here I calculate the temporal dependence of the A+ indicator analytically in a simplied model of the evolution of the blue straggler star distribution under dynamical friction only.]]></p></abstract>
<abstract abstract-type="short" xml:lang="es"><p><![CDATA[RESUMEN Las estrellas rezagadas azules tienen masas mayores que las de las estrellas típicas de los cúmulos globulares, puesto que se originan de la fusión de dos estrellas. En consecuencia, experimentan fricción dinámica, y se acercan paulatinamente al centro del cúmulo. Se han propuesto recientemente varios indicadores del grado de relajamiento dinámico de un cúmulo globular basados en la distribución radial de las rezagadas azules. El más exitoso es el indicador de Alessandrini (A+), que es la integral de la distribución acumulada de las rezagadas azules menos la de estrellas menos masivas. A+ se correlaciona con la edad dinámica del cúmulo tanto en simulaciones realistas como en las observaciones. Aquí calculo analíticamente la dependencia con el tiempo del indicador A+, usando un modelo simplificado de la evolución de la distribución de las rezagadas azules, que toma en cuenta sólo la fricción dinámica.]]></p></abstract>
<kwd-group>
<kwd lng="en"><![CDATA[blue stragglers]]></kwd>
<kwd lng="en"><![CDATA[globular clusters: general]]></kwd>
<kwd lng="en"><![CDATA[methods: analytical]]></kwd>
</kwd-group>
</article-meta>
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