lect 8 part 1

lect 8 part 1 - 22-year Solar cycle: Suns magnetic field...

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1 22-year Solar cycle : Sun’s magnetic field reverses polarity every 11 years Sunspot group moving: the sunspots in front are called the “preceding members” All preceding members on a given hemisphere have the same polarity, and opposite to the preceding members on the other hemisphere The magnetic-dynamo model suggests that many features of the solar cycle are due to changes in the Sun’s magnetic field The solar magnetic changes are caused by convection and the Sun’s differential rotation Rotation of the Solar Interior Differential rotation persist through the convection zone . In the radiative zone the Sun rotates as a rigid Body (27 days) Magnetic field may originate between the Radiative and convective Zone Helioseismology : rotation rate in the Sun’s interior is determined by comparing the speeds of sound waves in the interior
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2 Solar cycle is not always regular… • Reversal of magnetic field: one pole could go earlier than the other (example, two north poles may be present!) • Sunspot cycles may - vanish for years: No sunspots were observed from 1645 to 1715, record low temperatures in Europe, and severe drought in western United States. - increase activity: during 11-12 centuries, climate was warmer than today. Then, variations in solar activity appear to affect climate on Earth The active Sun Chromosphere seen through an H α filter The Sun seen through an UV filter
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3 The Sun’s magnetic field also produces other forms of solar activity • A solar flare is a brief eruption of hot, ionized gases from a sunspot group • A coronal mass ejection is a much larger eruption that involves immense amounts of gas from the corona Coronal mass ejections The Nature of the Stars
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This note was uploaded on 02/06/2011 for the course ASTR 113 taught by Professor Geller during the Spring '08 term at George Mason.

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lect 8 part 1 - 22-year Solar cycle: Suns magnetic field...

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