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A Tejútrendszer Szerkezete Tóth L A Tejútrendszer szerkezete Tóth L. Viktor XML to PDF by RenderX XEP XSL-FO F ormatter, visit us at http://www.renderx.com/ A Tejútrendszer szerkezete Tóth L. Viktor Szerzői jog © 2013 Eötvös Loránd Tudományegyetem E könyv kutatási és oktatási célokra szabadon használható. Bármilyen formában való sokszorosítása a jogtulajdonos írásos engedélyéhez kötött. Készült a TÁMOP-4.1.2.A/1-11/1-2011-0073 számú, „E-learning természettudományos tartalomfejlesztés az ELTE TTK-n” című projekt keretében. Konzorciumvezető: Eötvös Loránd Tudományegyetem, konzorciumi tagok: ELTE TTK Hallgatói Alapítvány, ITStudy Hungary Számítástechnikai Oktató- és Kutatóközpont Kft. XML to PDF by RenderX XEP XSL-FO F ormatter, visit us at http://www.renderx.com/ Tartalom Előszó ........................................................................................................................................ vii A Tejútrendszer korai kutatásának néhány érdekessége ...................................................................... viii Referenciák és további olvasnivaló: .......................................................................................... xi 1. A Tejútrendszer alapvonásai ......................................................................................................... 1 1.1 Alapvető paraméterek ....................................................................................................... 1 1.2 Alrendszerek .................................................................................................................... 3 1.2.1. A Galaktikus Korong (Disk) .................................................................................... 4 1.2.2. A Galaktikus Dudor (Bulge) .................................................................................... 6 1.2.3. A Galaktikus Halo ................................................................................................. 6 Referenciák és további olvasnivaló a fejezet témájában: ................................................................ 8 2. Csillaghalmazok és asszociációk ................................................................................................... 9 2.1. Gömbhalmazok ............................................................................................................... 9 2.1.1. A gömbhalmazok alapvető tulajdonságai ................................................................... 9 2.1.2. A gömbhalmazok HRD-je ..................................................................................... 10 2.1.3. Kék horizontális ág (BHB) ..................................................................................... 11 2.1.4. Kék csellengők (blue stragglers) ............................................................................. 11 2.1.5. Gömbhalmaz katalógusok ...................................................................................... 12 2.2. Nyílthalmazok ............................................................................................................... 12 2.2.1. A nyílthalmazok alapvető tulajdonságai ................................................................... 12 2.2.2. A nyílthalmazok HRD-je ....................................................................................... 13 2.2.3. A nullakorú fősorozat (ZAMS) .............................................................................. 14 2.2.4. Nyílthalmazok kora .............................................................................................. 15 2.2.5. Mozgási halmazok és csillagáram parallaxis .............................................................. 19 2.3. Asszociációk ................................................................................................................. 21 2.3.1. OB asszociációk .................................................................................................. 21 2.3.2. R és T asszociációk .............................................................................................. 23 2.4. Csillag-gáz komplexumok ................................................................................................ 25 Referenciák és további olvasnivaló a fejezet témájában: ............................................................... 26 3. Távolságmérés a Tejútrendszerben ............................................................................................... 28 3.1. A csillagászati távolságmérési módszerek fajtái .................................................................... 28 3.2. Geometriai módszerek ..................................................................................................... 28 3.3 Fotometriai módszerek ..................................................................................................... 33 3.3.1. Úgynevezett „standard gyertyák” ............................................................................ 34 3.4. A cefeida parallaxis ........................................................................................................ 34 3.4.1. A periódus-luminozitás reláció felfedezése ................................................................ 34 3.4.2. A cefeidák használatának előnye a távolság meghatározásban ....................................... 38 3.4.3. A cefeida pulzáló változók fizikai leírásának alapjai ................................................... 38 3.4.4. A periódus-luminozitás reláció alkalmazása a gyakorlatban .......................................... 39 3.5. Egyéb távolság meghatározási módszerek ........................................................................... 41 3.6. Példa: a Tejútrendszer centrumának távolsága ...................................................................... 41 Referenciák és további olvasnivaló a fejezet témájában: ............................................................... 43 4. Sztellárstatisztika és sztellárkinematika ......................................................................................... 45 4.1 Sztellárstatisztikai vizsgálatok ............................................................................................ 45 4.2 A sztellárstatisztika alapegyenlete ....................................................................................... 46 4.3 Kinematika I. – Individuális csillagmozgások ....................................................................... 50 4.3.1. A sajátmozgás ..................................................................................................... 50 4.3.2. A radiális sebesség ............................................................................................... 51 4.4 Kinematika II. – A Nap pekuliáris mozgása ......................................................................... 52 4.4.1. Apex ................................................................................................................. 52 4.4.2. Vonatkoztatási rendszer kitűzése ............................................................................. 52 4.4.3. Lokális nyugalmi pont meghatározása ...................................................................... 53 4.5 Kinematika III. – Csillagcsoporton belüli mozgások ............................................................... 54 Referenciák és további olvasnivaló a fejezet témájában: ............................................................... 56 5. A Tejútrendszer rotációja ............................................................................................................ 58 5.1. Forgás megfigyelése ....................................................................................................... 58 iii XML to PDF by RenderX XEP XSL-FO F ormatter, visit us at http://www.renderx.com/ A Tejútrendszer szerkezete 5.2. Oort-féle nyírási és forgási együtthatók .............................................................................. 61 5.2.1. Nyírási együttható és ráta ...................................................................................... 61 5.2.2. Forgási együttható ................................................................................................ 61 5.3. A rotációs görbe ............................................................................................................. 61 5.4 Sztellárdinamika, tömegmodellek ....................................................................................... 62 5.4.1. Rotációs görbe és tömegeloszlás ............................................................................. 62 5.4.2. Oort és Schmidt tömegmodellje .............................................................................. 63 5.4.3. Becslés a tömegre a Nap Galaktikus pályáján belül ..................................................... 64 5.4.4. A Tejútrendszer tömege ......................................................................................... 64 Referenciák és további olvasnivaló a fejezet témájában: ............................................................... 65 6. A Tejút spirális szerkezete .......................................................................................................... 66 6.1. Spirálkar indikátorok ....................................................................................................... 66 6.1.1. A spirálkarok megjelenési formái ............................................................................ 66 6.1.2. OB asszociációk és HII zónák ................................................................................ 67 6.1.3. Óriás molekulafelhők és HI szuperfelhők .................................................................
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