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Astronomy C - Variable Stars

Astronomy C - Variable Stars. A. Pulsating Variables: 1) Long Period Variables a) Mira type b) Semiregular 2) Cepheids 3) RR Lyrae 4) RV Tarui B. Cataclysmic (Eruptive) Variables: 1) T Tauri 2) Novae 3) Dwarf Novae

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Astronomy C - Variable Stars

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  1. Astronomy C - Variable Stars A. Pulsating Variables: 1) Long Period Variables a) Mira type b) Semiregular 2) Cepheids 3) RR Lyrae 4) RV Tarui B. Cataclysmic (Eruptive) Variables: 1) T Tauri 2) Novae 3) Dwarf Novae 4) Recurrent Novae 5) Supernovae a) Type II b) Type Ia

  2. Astronomy C - Variable Stars A. Pulsating Variables: 1) Long Period Variables a) Mira type Mira b) Semiregular Betelgeuse 2) Cepheids Delta Cephei 3) RR Lyrae [Globular Clusters] 4) RV Tarui R Scuti B. Cataclysmic (Eruptive) Variables: 1) T Tauri [Protostars] 2) Novae GK Persei, Nova Aquilae 3) Dwarf Novae Z Cam, SS Cygni 4) Recurrent Novae [between Dwarf and Nova] 5) Supernovae a) Type II Cas A, SN 1987A, DEM L316 b) Type Ia Tycho’s SNR, DEM L316

  3. Light Curves – Variation over Time Maximum (Maxima) Minimum (Minima) Period Apparent Magnitude vs Julian Day

  4. A. Pulsating Variable Stars; 1) Long Period Variables (LPVs) a) Miras Omicron Ceti (Mira) 80 – 1000 days, 2.5 – 5.0 mag b) Semiregular Variables Betelgeuse (Alpha Orionis) 30 – 1000 days, 1.0 – 2.0 mag

  5. Semiregular Mira Instability Strip

  6. 2) Cepheid Variable Stars Delta Cephei

  7. 2) Cepheids [Periods of 1 – 70 days, 1.0 – 2.0 mag] Delta Cephei

  8. A Cepheid Variable Star in M100

  9. 3) RR Lyrae Variable Stars 47 Tuc Periods of a few hours to one day, .3– 2.0 mag

  10. Cepheid and RR Lyrae Variable Stars Period-Luminosity Relationship and The Distance Modulus: M = m - 5log10 (r) 10 [Mv = 0.75]

  11. 4) RV Tauri – a Stellar Missing Link? R Scuti

  12. Cepheid Instability Strip Semiregular RR Lyrae Mira Instability Strip

  13. B. Cataclysmic (Eruptive) Variables • T Tauri; proto-star stage for • mid-sized stars

  14. Cepheid Instability Strip RV Tauri Semiregular RR Lyrae Mira Instability Strip T-Tauri

  15. Stellar Nurseries - sites of protostar & T-Tauri formation

  16. M 42 – The Orion Nebula

  17. 2) Novae Close binary systems – main sequence star & a white dwarf 1 to 300 days, 7.0 – 16.00 mags

  18. Novae: GK Persei Nova Aquilae

  19. 3) Dwarf Novae Dwarf Novae: Close binary systems – main sequence star, white dwarf and an accretion disk Two of three subclasses; U Gem – SS Cygni Z Cam – Z Cam

  20. SS Cygni

  21. Dwarf Novae: SS Cygni Z Cam

  22. 4) Recurrent Novae Close binary systems – main sequence star & a white dwarf 1 to 300 days, 7.0 – 16.00 mags *** Similar to novae but often resemble dwarf novae

  23. 5) Supernovae a) Type II SN 1987A Cas A

  24. b) Type Ia Mira Tycho’s SNR

  25. DEM L316 Type Ia Supernova Type II Supernova

  26. MZ 3 – The Ant Nebula (planetary nebula)

  27. Algol Beta Persei Eclipsing Binary

  28. Cosmological Distances Variables Cepheids RR Lyrae Spectroscopic Parallax

  29. Cosmological Distances Spectroscopic Parallax The Distance Modulus: M = m - 5log10 (r) 10 The Distance Modulus: M = m - 5log10 (r) 10 Cepheids

  30. Cosmological Distances & Candles Type Ia Supernovae – Standard Candle Mv = -19.5

  31. Basic Equations and Relationships The Distance Modulus: M = m - 5log10(r) 10 Kepler’s 3rd Law: (MA + MB) = a3 p2 v = d ; a = v ; 2π a = vP ; Fc = mac ; ac = v2 = rω2 t t r 1 pc = 206,265 au = 3.26 ly = 3.08 x 1016m 1° = 60 arcmin = 60´ ; 1´ = 60 arcsec = 60˝ Inverse Square Law: L = 1/r2 Circumference, Area, Surface Area, and Volume of a Sphere REARRANGE ALL EQUATIONS FOR EACH VARIABLE

  32. JD 2449050

  33. JD 2449835 43 74 55 59 W Cyg 64 53 61 40 68 55 67 67 69 69 75 70

  34. Phase Diagrams 1) Cepheid Light Curve 2) Superposition of Periods 4) Same data starting at Maxima 3) Same Data Plotted Twice

  35. O – C Diagrams (Observed minus Calculated) Theory Matches Observation Perfectly Periodic Perfectly Periodic Perfectly Periodic Correct Epoch Change in Period Wrong Period Correct Epoch Correct Period **True Period Shorter then Lenthens **True Period longer Perfectly Periodic Periodic NOT Perfectly Periodic Period Unchanged Epoch has Changed Correct Period Wrong Epoch Different Period Each Day ** The slope of each line is the difference between its period and the estimated period.

  36. Stellar Evolution – A Journey with Chandra

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