ASTR 1020 1st EditionExam # 1 Study GuideLecture 1 (January 13)Our Place in the UniverseDefine & give the formulas/equivalents for astronomical unit, Parsec, light-year, momentum, netforce, and angular momentum. - An astronomical unit is the average distance between the Earth and Sun. (1.5 x 108km=1 AU ¿- A Parsec is the typical distance between stars as defined the angular wobble caused by Earth’s orbit. (3.1 x 1013km ¿- A light-year is the distance light can travel in one year. (9.5 x 1012km¿- Momentum: Mass x velocity- Net Force: Changes momentum, causing acceleration- Rotational momentum of a spinning or orbiting object is known as angular momentum.Angular momentum = mass x velocity x distance from axisLecture 2 (January 15) Motion & EnergyWhat are Newton’s 3 Laws?1. An object on motion stays in motion unless acted upon by a net force2. Force = mass x acceleration3. Every action has an equal and opposite reactionWhat is the equation for kinetic motion?= 12mv2For radiative light energy?- Photons have energy hcwavelength❑H = Planck’s constantC = speed of lightWhat is Universal Law of Gravitation?1. Every mass attracts every other mass2. Attraction is directly proportional to product of other masses3. Attraction is inversely proportional to the square of distance between centers.Fg=GM1M2d2❑Newton’s Version of Kepler’s 3rd Law?1.M1+M2¿ p¿¿M1+M2=∑of masses(solar mass)P = orbital period (year)A = average orbital distance (AU)- Useful for any two objects on spaceKepler’s Other Laws?- Planets move faster when closer to the sun (k’s 2nd law)- Total orbital energy (gravitational and kinetic) stays constant if there is no external force.Lecture 3 (January 20) Atoms & LightDefine atomic number and atomic mass number- Atomic Number: number of protons in nucleus- Atomic mass number: number of protons and neutronsExplain the difference between Continuous Spectrum, Emission Line Spectrum, and Absorption Line Spectrum.- Continuous SpectrumThe spectrum of a common (incandescent) light bulb spans all visible wavelengths- Emission Line SpectrumThin or low-density cloud of gas emits light only at specific wavelengths that depend on its composition, producing a spectrum with bright emission lines.- Absorption Line SpectrumA cloud of gas between us and a lightbulb can absorb light of specific wavelengths leaving dark absorption lines.Properties of Thermal Radiation1. Hotter objects emit more light at all frequencies per unit area2. Hotter objects emit photons with higher average energy.Lecture 4 (January 22)RelativityDescribe each Theory of Relativity- Special Theory of Relativity (1905)Usual notions of space and time must be revised for speed approaching light speed (c), E=mc2- General Theory of Relativity (1915)Expands special theory to include "curved space-time”What are the absolutes of Relativity? 1. Laws of nature are the same for everyone2. The speed of light is the same for everyoneKey Ideas of General Relativity?- Gravity arises from distortions of space-time by the distribution of mass- Time runs slowly in gravitational fields- Black holes can exist in space-time- Rapid changes in the motion of large masses can cause gravitational wavesTests of Relativity- First test of speed of light comes from the Michelson-Morley Experiment- Time dilation happens routinely to subatomic particles the approach the speed of light in accelerators- Time dilation has also been verified through precision measurements in airplanes moving at much slower speeds- Prediction that E=mc2 is verified daily in nuclear reactors and in the core of the SunLecture 5 (January 27)The SunWhat are the properties of the Sun?- Radius:7 x 108 m (109 times Earth)- Mass:2 x 1030 kg (300,000 Earths)- Luminosity:3.8 x 1026 watts- Weight of upper layers compresses lower layers - The InteriorGravitational force pushes sun inwardSun’s interior generates pressure outward Pressure changes are hydrostatic equilibriumInterior is more dense and hotter- Core:Hot enough for nuclear fusion~ 15 million K- Outer layers:Temperature drops towards surface~ 5800 KDescribe Fusion and Fission- FissionBig nucleus splits into smaller pieces (Nuclear power plants)- FusionSmall nuclei stick together to make a bigger one (Sun, stars)Only possible at high temperature (over 10 million K) in the Sun’s coreDescribe Energy Transport in Solar Interior- The hotter radiation zone is relatively transparent (energy flow by light);- The cooler convection zone is more opaque (energy flow by convection)- The visible top layer shows granulation, with areas of rising gas (hotter, brighter)- Surrounded by areas of sinking gas (cooler, darker)Lecture 6 (January 29)The Sun: Our Star Describe the solar atmosphere- Photosphere (opaque limit)- Chromosphere (hotter, 6000K- Corona (really hot, 1,000,000K)- Solar wind (extends through solar system)What does magnetic activity near the sun cause?- Magnetic activity also causes solar prominences that erupt high above the sun’s surface.- Magnetic activity causes solar flares that send fast bursts of x-rays and charged particles into space. Lecture 7 (February 3)Surveying the StarsWhat is the equation to find distance in parsecs?d(¿ parsecs)=1p(¿ arcseconds)- Works well out to 200 parsecs (pc)What is luminosity?- Power radiated by a star= surface area xRate/unit area ¿4 π r2x σ T4Where R = radiusT = temperatureσ = Stefan-Boltzmann constantDefine Thermal Radiation- Thermal Radiation1. Hotter objects emit more light per unit area at all frequencies.2. Hotter objects emit photons with a higher average energy.- The color of a star is indicative of its temperature Red stars are relatively cool, while blue ones are hotter.Lecture 8 (February 5)Surveying the Stars, pt. 2What is Kepler’s Third Law?- (M1 + M2) P2=a3where M1 and M2 are the masses (MSUN),P is the period (years), anda is the separation or “semi-major axis” (AU)What are the Binary Star Systems?Visual Binary- Orbital motion can be measured directly• Eclipsing Binary- Combine light curve and Doppler shift curve: + radii, temperatures system inclination, masses• Spectroscopic Binary- Motion detected by Doppler ShiftsLecture 9 (February 10)Stellar Properties ReviewWhat are the equations for stekkar properties?- Luminosity: from brightness and distance 10.4 LSun - 106 LSun - Temperature: from color and spectral type 3,000 K - 50,000 K fast 10 billion years x 0.1 / 0.01 ~ 100 billion years- Mass: from period (p) and average