<?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>S0185-11012020000100055</article-id>
<article-id pub-id-type="doi">10.22201/ia.01851101p.2020.56.01.07</article-id>
<title-group>
<article-title xml:lang="en"><![CDATA[The Properties and Stability of Self-Gravitating, Polytropic Spheres with &#947; =1 to 1.4 Specific Heat Ratios]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Raga]]></surname>
<given-names><![CDATA[A.C.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Osorio-Caballero]]></surname>
<given-names><![CDATA[J. A.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Chan]]></surname>
<given-names><![CDATA[R. S.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Esquivel]]></surname>
<given-names><![CDATA[A.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Rodríguez-González]]></surname>
<given-names><![CDATA[A.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Lora]]></surname>
<given-names><![CDATA[V.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Rodríguez Ramírez]]></surname>
<given-names><![CDATA[J. C.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
</contrib-group>
<aff id="Af1">
<institution><![CDATA[,Universidad Nacional Autónoma de México Instituto de Ciencias Nucleares ]]></institution>
<addr-line><![CDATA[Ciudad de México ]]></addr-line>
<country>Mexico</country>
</aff>
<aff id="Af2">
<institution><![CDATA[,Universidad Nacional Autónoma de México Instituto de Radioastronomía y Astrofísica Teórica ]]></institution>
<addr-line><![CDATA[Morelia Michoacán]]></addr-line>
<country>Mexico</country>
</aff>
<aff id="Af3">
<institution><![CDATA[,Universidade de São Paulo Instituto de Astronomia, Geofísica e Ciências Atmosféricas ]]></institution>
<addr-line><![CDATA[SP ]]></addr-line>
<country>Brazil</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>55</fpage>
<lpage>62</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_arttext&amp;pid=S0185-11012020000100055&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_abstract&amp;pid=S0185-11012020000100055&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_pdf&amp;pid=S0185-11012020000100055&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="en"><p><![CDATA[ABSTRACT We study self-gravitating, hydrostatic spheres with a polytropic equation of state ECUACION (where &#947; is the specific heat ratio of the gas), considering structures with &#947; &#8776; 1 as a model for molecular cloud cores with small departures from isothermality. We derive the properties (i.e., mass, radius and center to edge density ratio) as a function of for the maximal stable sphere through an application of \Bonnor's stability criterion". We find that in the &#947; &#8776; 1 = 1 &#8594; 4/3 range the mass of the maximal sphere (for a given central temperature) is almost constant, and that its radius and center to edge density ratio are growing functions of . We therefore have maximal stable, self-gravitating spheres with similar masses, but with increasing center to edge density contrasts for increasing departures from isothermality.]]></p></abstract>
<abstract abstract-type="short" xml:lang="es"><p><![CDATA[RESUMEN Estudiamos esferas auto-gravitantes hidrostáticas con una ecuación de estado politrópica ECUACION (donde &#947; es el cociente de calores específicos del gas), considerando estructuras con &#947; &#8776; 1 como modelos de núcleos moleculares con pequeñas desviaciones del caso isotérmico. Derivamos las propiedades (masa, radio y cociente de densidades centro a borde) como función de para la esfera estable máxima, a través de una aplicación del \criterio de estabilidad de Bonnor". Encontramos que en el intervalo &#947; &#8776; 1 = 1 &#8594; 4/3 la masa de la esfera máxima (para una temperatura central dada) es casi constante, y que su radio y cociente de densidades centro a borde son funciones crecientes de . Por esto, tenemos esferas autogravitantes máximas con masas similares pero con contrastes de densidad centro a borde crecientes para mayores desviaciones respecto del caso isotérmico.]]></p></abstract>
<kwd-group>
<kwd lng="en"><![CDATA[ISM: clouds]]></kwd>
<kwd lng="en"><![CDATA[ISM: kinematics and dynamics]]></kwd>
<kwd lng="en"><![CDATA[stars: formation]]></kwd>
</kwd-group>
</article-meta>
</front><back>
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