4 6–4 ⊙ L 10 10 (radiating) (total) × ⊙ ⊙ 2 3 M M kg, − W ∼ 30 11 12 26 pc 10 10 10 10 ⊙ × × ∼ ∼ 2 M 600 pc 4 3 = = . 12 kpc ⊙ 0 ⊙ L M 1 Luminosity: Mass: Stellar density: ∼ 1
2kpc pc, distance: 675kpc), NOAO/AURA/NSF X Milky Way, IV 8 kpc Sun 208 km/s
8 kpc NGC 4565: W. McLaughlin Galactic Center X
220 Mill years/revolution 12 kpc 12
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D A C A Introduction 3 6–1 6–4 ⊙ L 10 10 (radiating) (total) × ⊙ ⊙ 2 3 M M kg, − W ∼ 30 11 12 26 pc 10 10 10 10 ⊙ × × ∼ ∼ 2 M 4 3 = = . ⊙ 0 ⊙ L M 1 Luminosity: Mass: Stellar density: ∼ 1 Milky Way, III Sun 208 km/s 8 kpc Galaxies: Classification Galactic Center X
220 Mill years/revolution
M83: ESO [VLT ANTU+FORS1] 12 kpc 12
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D D A A C C A A Introduction Virgo cluster, Burnell Schmidt telescope, NOAO/AURA/NSF M87 (=Virgo A, note jet; E0), NOAO/AURA/NSF Deep looks in the universe: galaxies as building blocks
SDSS M86 (lenticular, S0), NOAO/AURA/NSF Galaxy classification via the Hubble “tuning fork diagram” M90 (Sb), NOAO/AURA/NSF NGC 4565 (Sb, seen edge on), McLaughlin 5 , 6–13 ⊙ M (integer 12 /a !), typically ) b − Classification as a up to 10 ( old stars 10 M = Also elliptical, from x ) ⊙ M where 6 x designated cD. part; between 0 and 7) Ellipticals are low on dust andreddish gas, color (= low luminosity and low mass (10 Elliptical galaxies: E Monsters: mergers in galaxy clusters (e.g., M87 in Virgo), Elliptical Galaxies M104 (Sa; “Sombrero galaxy), HST/NASA
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D A C A M60 (NGC 4649), E1, U. of Alabama Elliptical Galaxies F E RIDE IA R M IC E O D
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G I A S E N 6–21 Spiral Galaxies
Spiral Galaxies: Elliptical nucleus plus spiral arms, designated Sa, Sb, Sc depending on opening angle of spiral (Sa: ∼ 10◦, Sc: ∼ 20◦) and dominance of nucleus.
Bluer than ellipticals.
11 Mass content ∼ 3 × 10 M⊙, with M/L ∼ 20,
Gas content increases from Sa to Sc from 1% to 8%.
Spiral arms probably due to density wave.
M51 (NGC 5194 and 5195), Sc and Irr, Kitt Peak 0.9 m
M51 (Sc), NOAO/AURA/NSF, T. Rector Spiral Galaxies 8
M83 (SABc, ESO) M51 (Sc; centre), HST/NASA NGC 1365 (SBb, VLT/FORS/ANTU): note old “reddish” bar, young spiral arms Large Magellanic Cloud (LMC; Irr I), Loke Kun Tan
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G I A S E N 6–25 Barred Galaxies
M95 (NGC 3351), SBb, INT Barred Galaxies: Classification as SBa, SBb, SBc similar to Sx galaxies, but additional presence of a bar (cause of bar production and stability are still debated).
Similar masses and gas content as in normal spirals.
Milky Way is a barred spiral. Large Magellanic Cloud (LMC; Irr I), AURA/NOAO/NSF Barred Galaxies 1 I Zwicky 18, Y. Izotov/T. Thuan/HST NGC 6946, T. Rector/AURA/Gemini 3 2 6–28 6–30 to 6 10 ”. 5), high dust . 16%), SMC, LMC 0 , masses vary ∼ 3 . ∼ ⊙ ∼ V Magellanic type M irregulars “ : no symmetry or spiral − 10 ⇒ B appreciably from 10 Examples: = Irr I M/L content ( arms, bright knots of O- and B-type stars, very blue ( All objects that do not fitrest in of the the classification: starburst galaxies, interacting galaxies, Active Galactic Nuclei,. . . : unsymmetrical and ⇒ “abnormal” = Irr II Irregular Galaxies: Irr I Irregular Galaxies: Irr II
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D D A A C C A A NGC 4449, Univ. Bonn Irregular Galaxies: Irr I M82, HST-WFPC Irregular Galaxies: Irr II Hoag’s Object, HST Cen A, ESO/WFI
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G I A S E N 6–41 AGN
NGC 3783: linear intensity scale logarithmic intensity scale
6...8 Active Galactic Nuclei (AGN): supermassive black holes (M ∼ 10 M⊙), accreting 1 ... 2 M⊙/year 10 =⇒ Luminosity ∼ 10 L⊙ (comparable to galaxy luminosity)
NGC 1300, HST AGN 3 4 5 6–42 6–42 ) ) 1 1 − − ) ) ⊙ ⊙ yr yr ⊙ ⊙ similar to similar to ) ) M M 1 AU 1 AU 7 7 ⊙ ⊙ M M L L ∼ ∼ 2 2 (10 (10 10 10 ...... 10 10 now now 1 1 , where material is ∼ ∼ ∼ ∼ L L ˙ ˙ ( ( M M ( ( jets: Seyfert galaxies active galactic nuclei active galactic nuclei jets: quasars, blazars... relativistic jets with without accelerated to the speed of light supermassive black hole accretion disk large luminosity Schwarzschild radius supermassive black hole accretion disk large luminosity Schwarzschild radius often • • • • • • • • • galactic black holes (although somewhat scaled up...) galactic black holes (although somewhat scaled up...) Structure of Structure of AGN AGN AGN AGN
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D D A A C C A A AGN AGN