<?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>S0185-11012021000100233</article-id>
<article-id pub-id-type="doi">10.22201/ia.01851101p.2021.57.01.17</article-id>
<title-group>
<article-title xml:lang="en"><![CDATA[&#8220;Head/tail plasmon&#8221; produced by a Gaussian ejection velocity pulse]]></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[Cantó]]></surname>
<given-names><![CDATA[J.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Castellanos-Ramírez]]></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[Hernández-Martínez]]></surname>
<given-names><![CDATA[L.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
</contrib-group>
<aff id="Af1">
<institution><![CDATA[,UNAM Instituto de Ciencias Nucleares ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>Mexico</country>
</aff>
<aff id="Af2">
<institution><![CDATA[,UNAM Instituto de Astronomía ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>Mexico</country>
</aff>
<aff id="Af3">
<institution><![CDATA[,UNAM Facultad de Ciencias ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>Mexico</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>00</month>
<year>2021</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>00</month>
<year>2021</year>
</pub-date>
<volume>57</volume>
<numero>1</numero>
<fpage>233</fpage>
<lpage>239</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_arttext&amp;pid=S0185-11012021000100233&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_abstract&amp;pid=S0185-11012021000100233&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_pdf&amp;pid=S0185-11012021000100233&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="en"><p><![CDATA[ABSTRACT We present an analytic model of a collimated ejection with a &#8220;single pulse" Gaussian ejection velocity. This ow produces a dense &#8220;head" (the leading working surface) joined to the outflow source by a &#8220;tail" of lower velocity material. For times greater than the duration of the ejection pulse, this tail develops a linear radial velocity vs. position structure. This \head/tail plasmon" structure is interesting for modelling astrophysical &#8220;bullets" joined to their outflow sources by structures with &#8220;Hubble law" radial velocity dependencies. We study the case of a Gaussian ejection velocity law with a constant and a Gaussian ejection density history, We compare these two cases, and find that the main effect of the different ejection density histories is to change the mass and the density stratification of the plasmon tail.]]></p></abstract>
<abstract abstract-type="short" xml:lang="es"><p><![CDATA[RESUMEN Presentamos un modelo analítico de una eyección colimada con una velocidad de eyección en forma de un único &#8220;pulso". Este flujo produce una &#8220;cabeza" densa (la superficie de trabajo) unida a la fuente por una &#8220;cola" de material de menor velocidad. Para tiempos mayores que la duración del pulso, esta cola desarrolla una dependencia lineal de velocidad radial vs. posición. Esta estructura de &#8220;plasmón cabeza/cola" es interesante para modelar &#8220;balas" astrofísicas unidas a su fuente por estructuras con velocidades radiales con forma de &#8220;ley de Hubble". Estudiamos el caso de una velocidad de eyección Gaussiana y con una historia de densidad de eyección constante o Gaussiana. Comparamos estos dos casos, y encontramos que el efecto más importante de las dos formas de la densidad de eyección es cambiar la masa y la estratificación de la densidad en la cola del plasmón.]]></p></abstract>
<kwd-group>
<kwd lng="en"><![CDATA[hydrodynamics]]></kwd>
<kwd lng="en"><![CDATA[shock waves]]></kwd>
</kwd-group>
</article-meta>
</front><back>
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