Simple hydrodynamical Simulations of the Circumnuclear Disk
Identifieur interne : 000173 ( Main/Corpus ); précédent : 000172; suivant : 000174Simple hydrodynamical Simulations of the Circumnuclear Disk
Auteurs : Robert F. Coker ; Michol H. Christopher ; Susan R. Stolovy ; Nick Z. ScovilleSource :
- Astronomische Nachrichten [ 0004-6337 ] ; 2003-09.
English descriptors
- KwdEn :
- GMC, Sgr A, simulation.
Abstract
The “circumnuclear disk” (CND) is a dense, clumpy, asymmetric ring‐like feature centered on Sgr A*. The outer edge of the CND is not distinct but the disk extends for more than 7 pc; the distinct inner edge, at a radius of ≃1.5 pc, surrounds the “mini‐spiral” of the HII region, Sgr A West. We present simple 3D hydrodynamical models of the formation and evolution of the CND from multiple selfgravitating infalling clouds and compare the results with recent observations. We assume the clouds are initially Bonner‐Ebert spheres, in equilibrium with a hot confining inter‐cloud medium. We include the gravitational potential due to the point‐mass of Sgr A* as well as the extended mass distribution of the underlying stellar population. We also include the effects of the ram pressure due to the stellar winds from the central cluster of early‐type stars. A single spherically symmetric cloud cannot reproduce the clumpy morphology of the CND; multiple clouds on diverse trajectories are required so that cloud‐cloud collisions can circularize the clouds' orbits while maintaining a clumpy morphology. Collisions also serve to compress the clouds, delaying tidal disruption while potentially hastening gravitational collapse. Low density clumps are disrupted before reaching the inner CND radius, forming short‐lived arcs. The outer parts of more massive clumps get tidally stripped, forming long‐lived low‐density wide‐angle arcs, while their cores potentially undergo gravitational collapse. The fine balance between resisting tidal disruption and preventing gravitational collapse implies that most if not all clumps are not stable for much more than an orbit. Thus, in order for the CND to be a long‐lived clumpy object, it must be continually fed by additional in‐falling clouds. Clouds that survive to small radii are likely to be the sites of present or future star formation. However, within a few parsecs of Sgr A*, the stellar winds decelerate any in‐falling cloud so that the wind‐cloud interface becomes Rayleigh‐Taylor unstable, potentially disrupting the cloud and inhibiting star formation.
Url:
DOI: 10.1002/asna.200385057
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The outer edge of the CND is not distinct but the disk extends for more than 7 pc; the distinct inner edge, at a radius of ≃1.5 pc, surrounds the “mini‐spiral” of the HII region, Sgr A West. We present simple 3D hydrodynamical models of the formation and evolution of the CND from multiple selfgravitating infalling clouds and compare the results with recent observations. We assume the clouds are initially Bonner‐Ebert spheres, in equilibrium with a hot confining inter‐cloud medium. We include the gravitational potential due to the point‐mass of Sgr A* as well as the extended mass distribution of the underlying stellar population. We also include the effects of the ram pressure due to the stellar winds from the central cluster of early‐type stars. A single spherically symmetric cloud cannot reproduce the clumpy morphology of the CND; multiple clouds on diverse trajectories are required so that cloud‐cloud collisions can circularize the clouds' orbits while maintaining a clumpy morphology. Collisions also serve to compress the clouds, delaying tidal disruption while potentially hastening gravitational collapse. Low density clumps are disrupted before reaching the inner CND radius, forming short‐lived arcs. The outer parts of more massive clumps get tidally stripped, forming long‐lived low‐density wide‐angle arcs, while their cores potentially undergo gravitational collapse. The fine balance between resisting tidal disruption and preventing gravitational collapse implies that most if not all clumps are not stable for much more than an orbit. Thus, in order for the CND to be a long‐lived clumpy object, it must be continually fed by additional in‐falling clouds. Clouds that survive to small radii are likely to be the sites of present or future star formation. However, within a few parsecs of Sgr A*, the stellar winds decelerate any in‐falling cloud so that the wind‐cloud interface becomes Rayleigh‐Taylor unstable, potentially disrupting the cloud and inhibiting star formation.</div></front></TEI><istex><corpusName>wiley</corpusName><author><json:item><name>Robert F. Coker</name><affiliations><json:string>Los Alamos National Laboratory, T‐087, Los Alamos, NM 87545</json:string></affiliations></json:item><json:item><name>Michol H. Christopher</name><affiliations><json:string>Caltech, Department of Astronomy, 105‐24, Pasadena, CA 91125</json:string></affiliations></json:item><json:item><name>Susan R. Stolovy</name><affiliations><json:string>SIRTF Science Center, Caltech, 314‐6, Pasadena, CA 91125</json:string></affiliations></json:item><json:item><name>Nick Z. 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We present simple 3D hydrodynamical models of the formation and evolution of the CND from multiple selfgravitating infalling clouds and compare the results with recent observations. We assume the clouds are initially Bonner‐Ebert spheres, in equilibrium with a hot confining inter‐cloud medium. We include the gravitational potential due to the point‐mass of Sgr A* as well as the extended mass distribution of the underlying stellar population. We also include the effects of the ram pressure due to the stellar winds from the central cluster of early‐type stars. A single spherically symmetric cloud cannot reproduce the clumpy morphology of the CND; multiple clouds on diverse trajectories are required so that cloud‐cloud collisions can circularize the clouds' orbits while maintaining a clumpy morphology. Collisions also serve to compress the clouds, delaying tidal disruption while potentially hastening gravitational collapse. Low density clumps are disrupted before reaching the inner CND radius, forming short‐lived arcs. The outer parts of more massive clumps get tidally stripped, forming long‐lived low‐density wide‐angle arcs, while their cores potentially undergo gravitational collapse. The fine balance between resisting tidal disruption and preventing gravitational collapse implies that most if not all clumps are not stable for much more than an orbit. Thus, in order for the CND to be a long‐lived clumpy object, it must be continually fed by additional in‐falling clouds. Clouds that survive to small radii are likely to be the sites of present or future star formation. 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The outer edge of the CND is not distinct but the disk extends for more than 7 pc; the distinct inner edge, at a radius of ≃1.5 pc, surrounds the “mini‐spiral” of the HII region, Sgr A West. We present simple 3D hydrodynamical models of the formation and evolution of the CND from multiple selfgravitating infalling clouds and compare the results with recent observations. We assume the clouds are initially Bonner‐Ebert spheres, in equilibrium with a hot confining inter‐cloud medium. We include the gravitational potential due to the point‐mass of Sgr A* as well as the extended mass distribution of the underlying stellar population. We also include the effects of the ram pressure due to the stellar winds from the central cluster of early‐type stars. A single spherically symmetric cloud cannot reproduce the clumpy morphology of the CND; multiple clouds on diverse trajectories are required so that cloud‐cloud collisions can circularize the clouds' orbits while maintaining a clumpy morphology. Collisions also serve to compress the clouds, delaying tidal disruption while potentially hastening gravitational collapse. Low density clumps are disrupted before reaching the inner CND radius, forming short‐lived arcs. The outer parts of more massive clumps get tidally stripped, forming long‐lived low‐density wide‐angle arcs, while their cores potentially undergo gravitational collapse. The fine balance between resisting tidal disruption and preventing gravitational collapse implies that most if not all clumps are not stable for much more than an orbit. Thus, in order for the CND to be a long‐lived clumpy object, it must be continually fed by additional in‐falling clouds. Clouds that survive to small radii are likely to be the sites of present or future star formation. However, within a few parsecs of Sgr A*, the stellar winds decelerate any in‐falling cloud so that the wind‐cloud interface becomes Rayleigh‐Taylor unstable, potentially disrupting the cloud and inhibiting star formation.</p></abstract><textClass xml:lang="en"><keywords scheme="keyword"><list><head>keywords</head><item><term>GMC</term></item><item><term>simulation</term></item><item><term>Sgr A</term></item></list></keywords></textClass><textClass><keywords scheme="Journal Subject"><list><head>article-category</head><item><term>Chapter 8: Morphology and Dynamics of the Central 10 Parsecs</term></item></list></keywords></textClass></profileDesc><revisionDesc><change when="2003-09">Published</change></revisionDesc></teiHeader></istex:fulltextTEI><json:item><original>false</original><mimetype>text/plain</mimetype><extension>txt</extension><uri>https://api.istex.fr/document/695ED1DF9E4D0518E678ACF50B1E87299A7E30E4/fulltext/txt</uri></json:item></fulltext><metadata><istex:metadataXml wicri:clean="Wiley, elements deleted: body"><istex:xmlDeclaration>version="1.0" encoding="UTF-8" standalone="yes"</istex:xmlDeclaration><istex:document><component version="2.0" type="serialArticle" xml:lang="en"><header><publicationMeta level="product"><publisherInfo><publisherName>WILEY‐VCH Verlag</publisherName><publisherLoc>Berlin</publisherLoc></publisherInfo><doi registered="yes">10.1002/(ISSN)1521-3994</doi><issn type="print">0004-6337</issn><issn type="electronic">1521-3994</issn><idGroup><id type="product" value="ASNA"></id></idGroup><titleGroup><title type="main" xml:lang="en" sort="ASTRONOMISCHE NACHRICHTEN">Astronomische Nachrichten</title><title type="subtitle">Astronomical Notes</title><title type="short">Astron. 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The outer edge of the CND is not distinct but the disk extends for more than 7 pc; the distinct inner edge, at a radius of ≃1.5 pc, surrounds the “mini‐spiral” of the HII region, Sgr A West. We present simple 3D hydrodynamical models of the formation and evolution of the CND from multiple selfgravitating infalling clouds and compare the results with recent observations. We assume the clouds are initially Bonner‐Ebert spheres, in equilibrium with a hot confining inter‐cloud medium. We include the gravitational potential due to the point‐mass of Sgr A* as well as the extended mass distribution of the underlying stellar population. We also include the effects of the ram pressure due to the stellar winds from the central cluster of early‐type stars.</p><p>A single spherically symmetric cloud cannot reproduce the clumpy morphology of the CND; multiple clouds on diverse trajectories are required so that cloud‐cloud collisions can circularize the clouds' orbits while maintaining a clumpy morphology. Collisions also serve to compress the clouds, delaying tidal disruption while potentially hastening gravitational collapse. Low density clumps are disrupted before reaching the inner CND radius, forming short‐lived arcs. The outer parts of more massive clumps get tidally stripped, forming long‐lived low‐density wide‐angle arcs, while their cores potentially undergo gravitational collapse. The fine balance between resisting tidal disruption and preventing gravitational collapse implies that most if not all clumps are not stable for much more than an orbit. Thus, in order for the CND to be a long‐lived clumpy object, it must be continually fed by additional in‐falling clouds. Clouds that survive to small radii are likely to be the sites of present or future star formation. However, within a few parsecs of Sgr A*, the stellar winds decelerate any in‐falling cloud so that the wind‐cloud interface becomes Rayleigh‐Taylor unstable, potentially disrupting the cloud and inhibiting star formation.</p></abstract></abstractGroup></contentMeta></header></component></istex:document></istex:metadataXml><mods version="3.6"><titleInfo lang="en"><title>Simple hydrodynamical Simulations of the Circumnuclear Disk</title></titleInfo><titleInfo type="abbreviated" lang="en"><title>Simulations of the Circumnuclear Disk</title></titleInfo><titleInfo type="alternative" contentType="CDATA" lang="en"><title>Simple hydrodynamical Simulations of the Circumnuclear Disk</title></titleInfo><name type="personal"><namePart type="given">Robert F.</namePart><namePart type="family">Coker</namePart><affiliation>Los Alamos National Laboratory, T‐087, Los Alamos, NM 87545</affiliation><description>Correspondence: Phone: +1‐505‐665‐1245, Fax: +1‐505‐665‐1231</description><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">Michol H.</namePart><namePart type="family">Christopher</namePart><affiliation>Caltech, Department of Astronomy, 105‐24, Pasadena, CA 91125</affiliation><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">Susan R.</namePart><namePart type="family">Stolovy</namePart><affiliation>SIRTF Science Center, Caltech, 314‐6, Pasadena, CA 91125</affiliation><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">Nick Z.</namePart><namePart type="family">Scoville</namePart><affiliation>Caltech, Department of Astronomy, 105‐24, Pasadena, CA 91125</affiliation><role><roleTerm type="text">author</roleTerm></role></name><typeOfResource>text</typeOfResource><genre type="article" displayLabel="article"></genre><originInfo><publisher>WILEY‐VCH Verlag</publisher><place><placeTerm type="text">Berlin</placeTerm></place><dateIssued encoding="w3cdtf">2003-09</dateIssued><copyrightDate encoding="w3cdtf">2003</copyrightDate></originInfo><language><languageTerm type="code" authority="rfc3066">en</languageTerm><languageTerm type="code" authority="iso639-2b">eng</languageTerm></language><physicalDescription><internetMediaType>text/html</internetMediaType><extent unit="figures">4</extent><extent unit="references">20</extent></physicalDescription><abstract lang="en">The “circumnuclear disk” (CND) is a dense, clumpy, asymmetric ring‐like feature centered on Sgr A*. The outer edge of the CND is not distinct but the disk extends for more than 7 pc; the distinct inner edge, at a radius of ≃1.5 pc, surrounds the “mini‐spiral” of the HII region, Sgr A West. We present simple 3D hydrodynamical models of the formation and evolution of the CND from multiple selfgravitating infalling clouds and compare the results with recent observations. We assume the clouds are initially Bonner‐Ebert spheres, in equilibrium with a hot confining inter‐cloud medium. We include the gravitational potential due to the point‐mass of Sgr A* as well as the extended mass distribution of the underlying stellar population. We also include the effects of the ram pressure due to the stellar winds from the central cluster of early‐type stars. A single spherically symmetric cloud cannot reproduce the clumpy morphology of the CND; multiple clouds on diverse trajectories are required so that cloud‐cloud collisions can circularize the clouds' orbits while maintaining a clumpy morphology. Collisions also serve to compress the clouds, delaying tidal disruption while potentially hastening gravitational collapse. Low density clumps are disrupted before reaching the inner CND radius, forming short‐lived arcs. The outer parts of more massive clumps get tidally stripped, forming long‐lived low‐density wide‐angle arcs, while their cores potentially undergo gravitational collapse. The fine balance between resisting tidal disruption and preventing gravitational collapse implies that most if not all clumps are not stable for much more than an orbit. Thus, in order for the CND to be a long‐lived clumpy object, it must be continually fed by additional in‐falling clouds. Clouds that survive to small radii are likely to be the sites of present or future star formation. However, within a few parsecs of Sgr A*, the stellar winds decelerate any in‐falling cloud so that the wind‐cloud interface becomes Rayleigh‐Taylor unstable, potentially disrupting the cloud and inhibiting star formation.</abstract><subject lang="en"><genre>keywords</genre><topic>GMC</topic><topic>simulation</topic><topic>Sgr A</topic></subject><relatedItem type="host"><titleInfo><title>Astronomische Nachrichten</title><subTitle>Astronomical Notes</subTitle></titleInfo><titleInfo type="abbreviated"><title>Astron. Nachr.</title></titleInfo><genre type="journal">journal</genre><subject><genre>article-category</genre><topic>Chapter 8: Morphology and Dynamics of the Central 10 Parsecs</topic></subject><identifier type="ISSN">0004-6337</identifier><identifier type="eISSN">1521-3994</identifier><identifier type="DOI">10.1002/(ISSN)1521-3994</identifier><identifier type="PublisherID">ASNA</identifier><part><date>2003</date><detail type="volume"><caption>vol.</caption><number>324</number></detail><detail type="issue"><caption>no.</caption><number>S1</number></detail><detail type="supplement"><caption>Suppl. no.</caption><number>1</number></detail><extent unit="pages"><start>629</start><end>634</end><total>6</total></extent></part></relatedItem><identifier type="istex">695ED1DF9E4D0518E678ACF50B1E87299A7E30E4</identifier><identifier type="DOI">10.1002/asna.200385057</identifier><identifier type="ArticleID">ASNA200385057</identifier><accessCondition type="use and reproduction" contentType="copyright">Copyright © 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim</accessCondition><recordInfo><recordContentSource>WILEY</recordContentSource><recordOrigin>WILEY‐VCH Verlag</recordOrigin></recordInfo></mods></metadata><enrichments><json:item><type>multicat</type><uri>https://api.istex.fr/document/695ED1DF9E4D0518E678ACF50B1E87299A7E30E4/enrichments/multicat</uri></json:item></enrichments><serie></serie></istex></record>Pour manipuler ce document sous Unix (Dilib)
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