<?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>S0185-11012020000100007</article-id>
<article-id pub-id-type="doi">10.22201/ia.01851101p.2020.56.01.02</article-id>
<title-group>
<article-title xml:lang="en"><![CDATA[Further Properties of 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>7</fpage>
<lpage>10</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_arttext&amp;pid=S0185-11012020000100007&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_abstract&amp;pid=S0185-11012020000100007&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_pdf&amp;pid=S0185-11012020000100007&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="en"><p><![CDATA[ABSTRACT The Alessandrini A+ indicator is a measure of star cluster dynamical evolution based on the mass-segregation of blue straggler stars. A+ is defined as the integral of the cumulative distribution of blue stragglers over log radius, minus a term related to the reference population used. In a companion paper I introduced a model of dynamical friction and calculated the A+ indicator analytically. Here I show further properties of the time evolution of A+, focusing on the physical interpretation of its time derivative dA+/dt. I find that dA+/dt is the mean of the reciprocal dyamical friction timescale, weighted by the density of blue stragglers. I show that it is non-negative (as expected based on monotonicity) due to the density of blue-stragglers being non-negative and that, for a radially non-decreasing dynamical friction timescale, dA+/dt is also non-decreasing with time, making A+ a convex function.]]></p></abstract>
<abstract abstract-type="short" xml:lang="es"><p><![CDATA[RESUMEN El indicador de Alessandrini A+ es una medida de la evolución dinámica de un cúmulo estelar basada en la segregación por masa de las estrellas rezagadas azules. Se define A+ como la integral de la distribución acumulada de las rezagadas azules sobre el logaritmo del radio, menos un término relacionado con la población de referencia usada. En el artículo anterior presenté un modelo con fricción dinámica y calculé analíticamente el indicador A+. Aquí muestro otras propiedades de A+, con énfasis en la interpretación física de su derivada con respecto al tiempo, dA+/dt. Encuentro que dA+/dt es la media del recíproco de la escala de tiempo dinámica, ponderada por la densidad de rezagadas azules. Muestro que no es negativa, pues la densidad de las rezagadas azules no es negativa. Muestro también que si la escala de tiempo de la fricción dinámica no decrece con el radio, entonces dA+/dt no decrece con el tiempo, lo que hace que A+ sea una función convexa.]]></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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