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Tuning Fork Diagram (modified from Hubble to include S0s)

Tuning Fork Diagram (modified from Hubble to include S0s). Irr I. “ Early ”. “ Late ”. Irr II. Fundamental Characteristics of Galaxies: Ellipticals. Primarily Pop II stars (old, metal-poor) and old Pop I stars Virtually no cold gas or dust, no active star formation

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Tuning Fork Diagram (modified from Hubble to include S0s)

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  1. Tuning Fork Diagram (modified from Hubble to include S0s) Irr I “Early” “Late” Irr II

  2. Fundamental Characteristics of Galaxies: Ellipticals • Primarily Pop II stars (old, metal-poor) and old Pop I stars • Virtually no cold gas or dust, no active star formation • Some large ellipticals have significant HOT (X-ray) gas component; frequently found in cluster environments • “red and dead” (at the present day, z=0)

  3. Fundamental Characteristics of Galaxies: Spirals • 3 principle components: bulge, disk, luminous halo • Halo: Pop II stars, little gas or dust, no star formation • Bulge: Pop I and Pop II stars, cold gas, dust, active star formation • Disk: Pop I in arms, cold gas, dust, active star formation, hot gas in the form of HII regions, planetary nebulae and some X-ray sources • “Lateness” correlates with cold gas content and star formation rate

  4. Fundamental Characteristics of Galaxies: Irregulars • Pop I and Pop II • Active star formation (abundant cold gas and dust)

  5. Elliptical Galaxy Spectrum - NGC 7512 No emission lines, prominent absorption features from ionized Ca, neutral Mg, and CN molecule (G-band). Note: lines have been identified in the rest-frame of the galaxy! Here z = 0.024.

  6. Late-type Spiral Galaxy Spectrum - Zw 496-001 Strong absorption features seen in E spectrum are weak or absent; also strong emission lines from neutral H and ionized O (hot gas)

  7. Fundamental Characteristics of Galaxies Note: masses and diameters below refer to visible regions only Ellipticals Spirals Irregulars M (Msun) 105 to 1013 109 to 4x1011 108 to 3x1010 L (Lsun) 3x105 to 1011 108 to 2x1010 107 to 109 Diam. (kpc) 1 to 200 5 to 50 1 to 10 Dust? ~none yes (disk & bulge) yes Spectral Type K K ; F-K; A-F A-F MHI/Mtot ~zero ~2%; ~5%; ~10% ~22% Sa; Sb; Sc Spectra of normal ellipticals do not contain emission lines; Spectra of late-type spirals and irregulars do contain emission lines

  8. Surface Brightness Profile - NGC 3379 (giant elliptical) Surface Brightness (mags/arcsec2) Dashed line is a deV law r1/4

  9. King Models - A Family of Curves deV law would be a straight line on this plot Note: “Isothermal” sphere is classic model where density is r( r ) ~ 1/r2 Surface Brightness r1/4

  10. Error Function

  11. King Models and Observed Objects NGC 6388 Circles: globular cluster NGC 6388 Squares: globular cluster NGC 5053 Triangles: Sculptor dwarf galaxy NGC 5053 Sculptor Dwarf Galaxy

  12. Giant Elliptical NGC 4472 (c = 2.35) SDSS image Solid line is King Model with c = 2.35

  13. deV vs. King: NGC 3379 Dots: observations Dashed line: deV law Solid line: King model, c = 2.2

  14. Two Galaxies in Same Cluster: Dwarf E and Giant E Dashed - Giant E, r1/4 Solid - Dwarf E, exp[-r/rs]

  15. cD Galaxy - The Biggest of the Big cD Line: deV Line: deV law ?

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