quiz9 - MASSACHUSETTS INSTITUTE OF TECHNOLOGY Physics Department Earth Atmospheric and Planetary Sciences Department Astronomy 8.282J12.402J Quiz 2 Name

quiz9 - MASSACHUSETTS INSTITUTE OF TECHNOLOGY Physics...

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MASSACHUSETTS INSTITUTE OF TECHNOLOGY Physics Department Earth, Atmospheric, and Planetary Sciences Department Astronomy 8.282J-12.402J April 13, 2005 Quiz 2 Name Solutions (please print) Last First 1. Work any 7 of the 10 problems - indicate clearly which 7 you want graded. 2. Spend 10 or 15 minutes reviewing the problems, and select 7. 3. Immediately after this you have two continuous hours to work the problems. 4. All problems are worth 14 points; everyone gets 2 points just for taking the exam. 5. Closed book exam; you may use two pages of notes, and a calculator. 6. Wherever possible, try to solve the problems using general analytic expressions. Plug in numbers only as a last step. 7. If you have any questions, e-mail the Instructor. 8. Turn exam in during lecture, Friday, April 15. Time Started: Time Stopped: Signature Problem Grade Grader 1 2 3 4 5 6 7 8 9 10 Total
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APPROXIMATE VALUES OF USEFUL CONSTANTS Constant cgs units mks units c (speed of light) G (gravitation constant) k (Boltzmann’s constant) h (Planck’s constant) m proton eV (electron Volt) M (solar mass) L (solar luminosity) R (solar radius) σ (Stefan-Boltzmann cons) ˚ A(Angstrom) 3 × 10 10 7 × 10 8 1 . 4 × 10 16 6 . 6 × 10 27 1 . 6 × 10 24 1 . 6 × 10 12 2 × 10 33 4 × 10 33 7 × 10 10 6 × 10 5 10 8 cm/sec dyne-cm 2 /g 2 erg/K erg-sec g erg g erg/sec cm erg/cm 2 -sec-K 4 cm 3 × 10 8 7 × 10 11 1 . 4 × 10 23 6 . 6 × 10 34 1 . 6 × 10 27 1 . 6 × 10 19 2 × 10 30 4 × 10 26 7 × 10 8 6 × 10 8 10 10 m/sec N-m 2 /kg 2 J/K J-sec kg J kg J/sec m J/m 2 -sec-K 4 m km (kilometer) 10 5 cm 10 3 m pc (parsec) kpc (kiloparsec) Mpc (megaparsec) year day 3 × 10 18 3 × 10 21 3 × 10 24 3 × 10 7 86400 cm cm cm sec sec 3 × 10 16 3 × 10 19 3 × 10 22 3 × 10 7 86400 m m m sec sec AU 1 (arc minute) 1 . 5 × 10 13 1 / 3400 cm rad 1 . 5 × 10 11 1 / 3400 m rad 1 �� (arc second) 1 / 200 , 000 rad 1 / 200 , 000 rad
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Problem1AstarintheAndromedagalaxyyieldsabolometricfluxattheEarthofF=1.0×1013ergscm2sec1(1.0×1016Wattsm2).IthasaB-Vcolorindexof-0.24.TakethedistancetoAndromedatobe1Mpc.Makeuseofthetablebelow,whereappropriate,toanswerthefollowingquestions(interpolatebetweenentriesusinganyinterpolationschemethatisreasonable).Thereferencefluxforabolometricmagnitudeof0.0isF0= 2.5×105ergscm2sec1(2.5×108Wattsm2).a.Findthebolometricmagnitude,Mbolofthestar. b.Whatistheapproximateeffectivetemperature,Teffective,ofthestar.
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