Astr 100 study guide exam 2 - Lecture 4 Definitions Photosphere low D Granule Dark edged region made from Convection Part of sun that you can see with

Astr 100 study guide exam 2 - Lecture 4 Definitions...

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Lecture 4 Definitions Photosphere: Part of sun that you can see with the naked eye (Optical) (where gas becomes opaque, source of most sunlight, low D) Granule: Dark edged region made from convection (energy outward from interior; brings heat to surface; this motion = granulation) Convection: Caused by hot material rising and cool material falling (up down up down) (action of heat rising by this movement) Chromosphere: Second of 3 main layers, sits just above the photosphere, just below solar transition region (inner atmosphere) (UV) Corona: Type of plasma atmosphere extending millions of kilometers into space (outer atmosphere) (xrays) Spectral Curve: Wavelength (color) Intensity (energy output per second, vertical axis): measures thermal radiation (spectral curve) Thermal Radiation: Hotter object, shorter wavelength (blue, hot, red, cooler: can help us tell objects temps) (temps tell us color) Fission: Big atomic nucleus splits into smaller pieces (nuclear power plants), Fusion: Small nuclei combine to make a bigger one (sun, stars) *Sun fuses 4 hydrogen nuclei into 1 helium nucleus, also needs high temperatures (above 10 million K) and densities *If particles move fast enough they can overcome repelling force of bare protons and fuse together and release energy (suns core only) *Fusion also produces neutrinos (direct evidence of fusion) (hard to detect) (they escape the sun immediately) *So far sun is halfway through its fuel, 5 billion years left (Sun fuses H to HE in core) *Energy gets out of the sun by bouncing photons out of the radiative zone Definitions (Sun spots) Sunspots: Regions on the sun that appear dark because they are cooler than the rest of the surface (last a few days to weeks, form in groups) *Appear dark in the photosphere, but bright in the suns atmosphere (sunspots are magnetic; inhibit mixture of hot plasma) *Peak in sunspot count = solar maximum, period with few = solar minimum (sunspot cycle duration = 11 yrs) *Sunspots show suns rotation (rotates fasted at equator and slowest at its poles = differential rotation) (@ cycle end field flips) *Sunspots develop because magnetic fields become twisted and strong fields break through the surface in tight loops Solar Flares: Violent explosion in the suns atmosphere with an energy = to hydrogen bombs *Occur when intense magnetic fields release their energy explosively Coronal Mass Ejections (CME’s): Huge bubbles of gas ejected from the sun (radio interferences travel at the same speed of light) Auroras: Energetic solar wind particles (Northern lights) (can damage satellites and power lines and radio lines) Prominences: Large jets of gas that follow magnetic field lines (solar flares caused when these lines break) (solar flares then cause CMEs) Definitions (properties of stars) Parallax: Difference in the apparent position of an object viewed along two different lines of sight (how we measure distance of stars)
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