<?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>S0185-11012010000200003</article-id>
<title-group>
<article-title xml:lang="en"><![CDATA[Echelle spectroscopy of the nuclei of the highly collimated bipolar planetary nebulae M 2-9 and M 1-91]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Torres-Peimbert]]></surname>
<given-names><![CDATA[S.]]></given-names>
</name>
<xref ref-type="aff" rid="A02"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Arrieta]]></surname>
<given-names><![CDATA[A.]]></given-names>
</name>
<xref ref-type="aff" rid="A03"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Bautista]]></surname>
<given-names><![CDATA[M]]></given-names>
</name>
<xref ref-type="aff" rid="A04"/>
</contrib>
</contrib-group>
<aff id="A02">
<institution><![CDATA[,Universidad Nacional Autónoma de México Instituto de Astronomía ]]></institution>
<addr-line><![CDATA[México D. F.]]></addr-line>
<country>México</country>
</aff>
<aff id="A03">
<institution><![CDATA[,Universidad Iberoamericana Depto. de Física y Matemáticas ]]></institution>
<addr-line><![CDATA[México D. F.]]></addr-line>
<country>México</country>
</aff>
<aff id="A04">
<institution><![CDATA[,Western Michigan University Department of Physics ]]></institution>
<addr-line><![CDATA[Kalamazoo MI]]></addr-line>
<country>USA</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>10</month>
<year>2010</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>10</month>
<year>2010</year>
</pub-date>
<volume>46</volume>
<numero>2</numero>
<fpage>221</fpage>
<lpage>243</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_arttext&amp;pid=S0185-11012010000200003&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_abstract&amp;pid=S0185-11012010000200003&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_pdf&amp;pid=S0185-11012010000200003&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="es"><p><![CDATA[Presentamos espectroscopia echelle del núcleo sin resolver de las nebulosas bipolares M 2-9 and M 1-91. Los espectros están dominados por líneas de emisión emitidas en un amplio intervalo de condiciones físicas. De las observaciones identificamos las líneas de emisión, las condiciones físicas y los movimientos relativos de las diferentes especies ionizadas en la región circunestelar de ambos objetos. Proponemos que las líneas prohibidas observadas se originan en la parte interior del toro extendido que rodea a cada objeto.]]></p></abstract>
<abstract abstract-type="short" xml:lang="en"><p><![CDATA[We present echelle spectroscopy of the unresolved nuclei of the bipolar planetary nebulae M 2-9 and M 1-91. The spectrum is dominated by emission lines emitted under a wide range of physical conditions. From the observations we identify the emission lines, derive physical conditions and relative motions of the different ionized species in the circumstellar region of both objects. We propose that the observed forbidden lines arise in the inner part of the extended torus that surrounds each object.]]></p></abstract>
<kwd-group>
<kwd lng="en"><![CDATA[planetary nebulae]]></kwd>
</kwd-group>
</article-meta>
</front><body><![CDATA[ <p align="center"><font face="verdana" size="4"><b> Echelle spectroscopy of the nuclei of the highly collimated bipolar planetary nebulae M 2&#150;9 and M 1&#150;91<sup><a href="#nota">1</a></sup></b></font></p>     <p align="center"><font face="verdana" size="2">&nbsp;</font></p>     <p align="center"><font face="verdana" size="2"><b>S. Torres&#150;Peimbert,<sup>2</sup> A. Arrieta,<sup>3</sup> and M. Bautista<sup>4 </sup></b></font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><i><sup>2 </sup>Instituto de Astronom&iacute;a, Universidad Nacional Aut&oacute;noma de M&eacute;xico, Apdo. Postal 70&#150;264, M&eacute;xico, D. F. 04510, M&eacute;xico</i> (<a href="mailto:silvia@astroscu.unam.mx">silvia@astroscu.unam.mx</a>).</font></p>     <p align="justify"><font face="verdana" size="2"><i><sup>3 </sup>Universidad Iberoamericana, Depto. de F&iacute;sica y Matem&aacute;ticas, Prol. Paseo de la Reforma 880, Lomas de Santa Fe, M&eacute;xico D. F. 01219, M&eacute;xico</i> (<a href="mailto:anabel.arrieta@uia.mx">anabel.arrieta@uia.mx</a>).</font></p>     <p align="justify"><font face="verdana" size="2"><i><sup>4 </sup>Department of Physics, Western Michigan University, Kalamazoo, MI 49008, USA.</i></font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2">Received 2010 January 21    <br>   Accepted 2010 May 20</font></p>     ]]></body>
<body><![CDATA[<p align="center"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><b>RESUMEN</b></font></p>     <p align="justify"><font face="verdana" size="2">Presentamos espectroscopia echelle del n&uacute;cleo sin resolver de las nebulosas bipolares M 2&#150;9 and M 1&#150;91. Los espectros est&aacute;n dominados por l&iacute;neas de emisi&oacute;n emitidas en un amplio intervalo de condiciones f&iacute;sicas. De las observaciones identificamos las l&iacute;neas de emisi&oacute;n, las condiciones f&iacute;sicas y los movimientos relativos de las diferentes especies ionizadas en la regi&oacute;n circunestelar de ambos objetos. Proponemos que las l&iacute;neas prohibidas observadas se originan en la parte interior del toro extendido que rodea a cada objeto.</font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><b>ABSTRACT</b></font></p>     <p align="justify"><font face="verdana" size="2">We present echelle spectroscopy of the unresolved nuclei of the bipolar plane&#150;tary nebulae M 2&#150;9 and M 1&#150;91. The spectrum is dominated by emission lines emitted under a wide range of physical conditions. From the observations we identify the emission lines, derive physical conditions and relative motions of the different ionized species in the circumstellar region of both objects. We propose that the observed forbidden lines arise in the inner part of the extended torus that surrounds each object.</font></p>     <p align="justify"><font face="verdana" size="2"><b><i>Key Words: </i></b>planetary nebulae: individual (M 2&#150;9, M 1&#150;91).</font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><a href="/pdf/rmaa/v46n2/v46n2a3.pdf" target="_blank">DESCARGAR ART&Iacute;CULO EN FORMATO PDF</a></font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     ]]></body>
<body><![CDATA[<p align="justify"><font face="verdana" size="2"><b>ACKNOWLEDGMENTS</b></font></p>     <p align="justify"><font face="verdana" size="2">ST&#150;P and AA have received support from DGAPA&#150;IN112708, Conacyt&#150;60967 and Conacyt&#150;46904 grants. We are grateful for the comments from the referee and many fruitful discussions with L. N. Georgiev.</font></p>     <p align="justify"><font face="verdana" size="2"><i>Note added in proof:</i> R. Corradi (private communication) kindly informed us that the distance of 650 pc assigned to M 2&#150;9 (Schwarz et al. 1997) is not correct, and that it should be 1.3 kpc. This value, if confirmed, would modify our size and time estimates by a factor of 2.</font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><b>REFERENCES</b></font></p>     <!-- ref --><p align="justify"><font face="verdana" size="2">Allen, D. A., &amp; Swings, J. 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