Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display 1 Announcements: Homework #6 due Tuesday Last problem requires that you collect information on the web on at least three separate days. Don’t wait until the last minute! Reading Quiz: Tuesday, March
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display 2 An incandescent bulb, fluorescent light, and the Sun emit ________, ________, and _________ spectra, respectively. a)Continuous, emission, absorption b)Continuous, absorption, emission c)Continuous, continuous, continuous d)Absorption, emission, continuous e)Absorption, emission, absoprtion
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display 3 The Doppler Effect
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display 4 Two stars orbiting one another. The diagram shows the orbital motion of one of the stars, and four different positions are marked (A, B, C, D). At which position is the light from the star redshifted? blueshifted? not shifted at all? a) A, C, B/D b) C, A, B/D c) B, D, A/C d) D, B, A/C B D C A
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display 5 The Sun as a Star (Chp. 11)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display 6 A Garden Variety Star Distance: 1.5 × meters Mass: 2 × kg Size: 7 × 10 8 meters Surface Temperature: 5800 K Gaseous! Made of: 92% Hydrogen 7.8% Helium 0.2% other Radar Measurements Laws of Gravity Angular Size Wien’s Law Pressure/Temperature Spectroscopy
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display 7 Density Wood block Aluminum block
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display 8 Solar Atmosphere: Temperature Profile
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display 9 Photosphere: where most of the photons escape the Sun. Approximately 500 km thick (small compared to radius!)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display 10 The Sun at Different Wavelengths
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display 11 Unfiltered light; optical; sunspots; photosphere
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display 12 Filtered optical (hydrogen emission); plages; chromosphere
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display 13 Ultra-violet emission; coronal holes, prominences; corona
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display 14 X-Ray emission; coronal holes, prominences; corona
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display 15 Different wavelengths probe different temperatures, different altitudes in the atmosphere. Photosphere: 5800 K; sunspots Chromosphere: 10,000 K; plages Corona: 3,000,000 K; prominences active regions
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display 16 Which of the following statements about the Sun’s atmosphere is false? a) The chromosphere is the region in which the colors producing white light are generated. b) The photosphere is where most of the photons escape into space c) The corona consists of very low density gas d) The temperature of the corona is higher than the temperature of the Sun’s “surface”.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display 17 The Magnetic Field of the Sun Current loop
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display 18 Observations reveal switching polarity Zeeman effect reveals magnetic nature of active regions.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display 19 Zeeman Effect
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display 20 Magnetic fields loop through the surface of the Sun like fibers in a carpet. Charged particles are accelerated by the magnetic force.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display 21 Close-up view of sunspot taken by TRACE satellite.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display 22 Prominences seen on solar limb
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display 23 Sunspots at base of prominence
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display 24 Breaking and reconnection of magnetic field lines dumps energy into upper atmosphere. Why is corona so hot?
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display 25 Solar Cycle The number of sunspots varies in an 11 year cycle Each sunspot peak is called a solar maximum
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display 26 Solar Cycle During each cycle, sunspots first appear far from the equator (30 degrees North) and then later appear close to the equator. You rarely/never see spots at high latitudes.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display 27 Butterfly Diagram
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display 28 Solar Cycle Magnetic Polarity switches every 11 years, making the true solar cycle a 22-year phenomenon.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display 29 Differential Rotation plays important role in 11-year cycle: Rotation period at equator: 25 days Rotation period at poles: 36 days
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display 30 Maunder Minimum : extended lull in solar activity “Little Ice Age” recorded in Europe