PowerPoint PresentationSlide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Stellar MassUrsa MajorAlcorMizar(Binary star)Gravitational Orbits AnimationBinary star (system): two stars orbiting a commoncenter of mass (CM).CM12r1r21221rr MMr2 = 3 AU, r1 = 1 AU 3 AU 1AU 3 MM21Kepler’s laws apply here . . .Yuk!2132M Ma PP: yearsa: AUM: Solar Masses322a m) G(M4 Pa = r1 + r2 = 4 AUSuppose: P = 8 yrs . . . 84 Pa M M2323211 M“Seeing” Binary Stars1. Visual Binary: Two stars seen in telescopee.g., MizarAlbireoSirius A & BABKruger 60Distance = 13 lyABL MAB0.01 L0.0034 LP = 44.6 yrsa = 9.5 AU0.28 M 0.16 M 2. Spectroscopic Binary: Motion of starsdetected via Doppler shift of spectrum lines.MizarEach star is itself binary!Earth* Doppler shift* No Doppler shiftSpectroscopic Binary Animation3. Eclipsing Binary: Stars mutually eclipseeach other.Earth* No eclipse* EclipseBinary ‘light curve’BrightnessTime½ orbit periodEclipsing Binary AnimationBinary Statistics* At least 50% of all stars reside in binaries.* The sun is apparently a
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