<?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>S0185-11012018000100004</article-id>
<title-group>
<article-title xml:lang="en"><![CDATA[A comparison of the radio and optical time-evolution of HH 1 and 2]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Rodríguez]]></surname>
<given-names><![CDATA[L. F.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<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[Rodríguez-Kamenetzky]]></surname>
<given-names><![CDATA[A.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
<xref ref-type="aff" rid="Aaf"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Carrasco-González]]></surname>
<given-names><![CDATA[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 Radioastronomía y Astrofísica ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>Mexico</country>
</aff>
<aff id="Af2">
<institution><![CDATA[,Universidad Nacional Autónoma de México Instituto de Ciencias Nucleares ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>Mexico</country>
</aff>
<aff id="Af3">
<institution><![CDATA[,Instituto de Astronomía Teórica y Experimental  ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>Argentina</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>00</month>
<year>2018</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>00</month>
<year>2018</year>
</pub-date>
<volume>54</volume>
<numero>1</numero>
<fpage>0</fpage>
<lpage>0</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_arttext&amp;pid=S0185-11012018000100004&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_abstract&amp;pid=S0185-11012018000100004&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_pdf&amp;pid=S0185-11012018000100004&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="en"><p><![CDATA[Abstract We present a comparison between the time-evolution over the past &#8776; 20 years of the radio continuum and H&#945; emission of HH 1 and 2. We find that the radio continuum and the H&#945; emission of both objects show very similar trends, with HH 1 becoming fainter and HH 2 brightening quite considerably (by about a factor of 2). We also find that the FH&#945;/Fff (H&#945; to free-free continuum) ratio of HH 1 and 2 has higher values than the ones typically found in planetary nebulae (PNe), which we interpret as an indication that the H&#945; and free-free emission of HH 1/2 is produced in emitting regions with lower temperatures (&#8776; 2000 K) than the emission of PNe (with &#8776; 104 K).]]></p></abstract>
<abstract abstract-type="short" xml:lang="es"><p><![CDATA[Resumen Presentamos una comparación entre la evolución temporal en los pasados &#8776; 20años de la emisión de radio continuo y de H&#945; de HH 1 y 2. Encontramos que el radio continuo y H&#945; de los dos objetos muestran evoluciones similares, con HH 1 debilitándose y HH 2 volviéndose considerablemente más brillante (aproximadamente un factor de 2). También encontramos que el cociente FH&#945;/Fff (entre H&#945; y el radio continuo) de HH 1 y 2 tiene valores mayores que los encontrados típicamente en nebulosas planetarias (PNe), lo cual interpretamos como una indicación de que la emisión libre-libre y de H&#945; de HH 1/2 se produce en regiones emisoras con temperaturas menores (&#8776; 2000 K) que la emisión de las PNe (con &#8776; 104 K).]]></p></abstract>
<kwd-group>
<kwd lng="en"><![CDATA[Herbig-Haro objects]]></kwd>
<kwd lng="en"><![CDATA[ISM: individual objects: HH1/2]]></kwd>
<kwd lng="en"><![CDATA[ISM: jets and outflows]]></kwd>
<kwd lng="en"><![CDATA[ISM: kinematics and dynamics]]></kwd>
<kwd lng="en"><![CDATA[shock waves]]></kwd>
<kwd lng="en"><![CDATA[stars: winds]]></kwd>
<kwd lng="en"><![CDATA[outflows]]></kwd>
</kwd-group>
</article-meta>
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