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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.

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Presentation on theme: "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."— Presentation transcript:

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) b) Semiregular Variables 80 – 1000 days, 2.5 – 5.0 mag Betelgeuse (Alpha Orionis) 30 – 1000 days, 1.0 – 2.0 mag

5 Mira Instability Strip Semiregular

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 Periods of a few hours to one day,.3– 2.0 mag 47 Tuc

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

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

13 Mira Instability Strip Semiregular Cepheid Instability Strip RR Lyrae

14 B. Cataclysmic (Eruptive) Variables 1)T Tauri; proto-star stage for mid-sized stars

15 Mira Instability Strip Semiregular Cepheid Instability Strip RR Lyrae T-Tauri RV Tauri

16 Stellar Nurseries - sites of protostar & T-Tauri formation

17 M 42 – The Orion Nebula

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

19 Novae: Nova Aquilae GK Persei

20 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

21 SS Cygni

22 Dwarf Novae: SS Cygni Z Cam

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24 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

25 5) Supernovae a) Type II Cas A SN 1987A

26 b) Type Ia Tycho’s SNR Mira

27 Type Ia Supernova Type II Supernova DEM L316

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29 MZ 3 – The Ant Nebula (planetary nebula)

30 Algol Beta Persei Eclipsing Binary

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35 Cosmological Distances Spectroscopic Parallax Variables Cepheids RR Lyrae

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

37  Type Ia Supernovae – Standard Candle Cosmological Distances & Candles M v = -19.5

38 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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41 JD 2449050

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43 JD 2449835 W Cyg 6140 43 55 59 53 68 55 69 67 64 75 74 70

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

45 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)

46 Stellar Evolution – A Journey with Chandra


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