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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
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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
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Light Curves – Variation over Time Maximum (Maxima) Minimum (Minima) Period Apparent Magnitude vs Julian Day
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A. Pulsating Variable Stars; 1) Long Period Variables (LPVs) a) Miras Omicron Ceti (Mira) b) Semiregular Variables 80 – 1000 days, 2.5 – 5.0 mag Betelgeuse (Alpha Orionis) 30 – 1000 days, 1.0 – 2.0 mag
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Mira Instability Strip Semiregular
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2) Cepheid Variable Stars Delta Cephei
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2) Cepheids [ Periods of 1 – 70 days, 1.0 – 2.0 mag] Delta Cephei
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A Cepheid Variable Star in M100
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3) RR Lyrae Variable Stars Periods of a few hours to one day,.3– 2.0 mag 47 Tuc
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Cepheid and RR Lyrae Variable Stars [Mv = 0.75] Period-Luminosity Relationship and The Distance Modulus: M = m - 5log10 (r) 10
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4) RV Tauri – a Stellar Missing Link? R Scuti
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Mira Instability Strip Semiregular Cepheid Instability Strip RR Lyrae
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B. Cataclysmic (Eruptive) Variables 1)T Tauri; proto-star stage for mid-sized stars
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Mira Instability Strip Semiregular Cepheid Instability Strip RR Lyrae T-Tauri RV Tauri
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Stellar Nurseries - sites of protostar & T-Tauri formation
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M 42 – The Orion Nebula
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2) Novae Close binary systems – main sequence star & a white dwarf 1 to 300 days, 7.0 – 16.00 mags
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Novae: Nova Aquilae GK Persei
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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
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SS Cygni
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Dwarf Novae: SS Cygni Z Cam
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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
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5) Supernovae a) Type II Cas A SN 1987A
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b) Type Ia Tycho’s SNR Mira
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Type Ia Supernova Type II Supernova DEM L316
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MZ 3 – The Ant Nebula (planetary nebula)
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Algol Beta Persei Eclipsing Binary
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Cosmological Distances Spectroscopic Parallax Variables Cepheids RR Lyrae
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Cosmological Distances Cepheids The Distance Modulus: M = m - 5log10 (r) 10 Spectroscopic Parallax The Distance Modulus: M = m - 5log10 (r) 10
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Type Ia Supernovae – Standard Candle Cosmological Distances & Candles M v = -19.5
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Basic Equations and Relationships The Distance Modulus: M = m - 5log 10 (r) 10 Kepler’s 3 rd Law: (M A + M B ) = a 3 p 2 v = d ; a = v ; 2π a = vP ; F c = ma c ; a c = v 2 = rω 2 t t r 1 pc = 206,265 au = 3.26 ly = 3.08 x 10 16 m 1° = 60 arcmin = 60´ ; 1´ = 60 arcsec = 60˝ Inverse Square Law: L = 1/r 2 Circumference, Area, Surface Area, and Volume of a Sphere REARRANGE ALL EQUATIONS FOR EACH VARIABLE
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JD 2449050
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JD 2449835 W Cyg 6140 43 55 59 53 68 55 69 67 64 75 74 70
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1) Cepheid Light Curve 3) Same Data Plotted Twice 2) Superposition of Periods 4) Same data starting at Maxima Phase Diagrams
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Theory Matches Observation Perfectly Periodic Correct Epoch Correct Period ** The slope of each line is the difference between its period and the estimated period. Perfectly Periodic Correct Epoch Wrong Period **True Period longer Perfectly Periodic Change in Period **True Period Shorter then Lenthens Perfectly Periodic Correct Period Wrong Epoch Periodic Period Unchanged Epoch has Changed NOT Perfectly Periodic Different Period Each Day O – C Diagrams (Observed minus Calculated)
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Stellar Evolution – A Journey with Chandra
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