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Exploring the Universe. Chapter 26. 26.1 Energy From the Sun. Review of Vocabulary. Core - central region, where nuclear fusion occurs. How does the sun produce energy?. Energy is produced in its central region by the fusion of hydrogen nuclei into helium nuclei.
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Exploring the Universe Chapter 26
Review of Vocabulary • Core - central region, where nuclear fusion occurs.
How does the sun produce energy? Energy is produced in its central region by the fusion of hydrogen nuclei into helium nuclei.
Question: What new isotope is produced by this fusion reaction? • hydrogen-1 • helium-4 • oxygen-16 • none
What new isotope is produced by this fusion reaction? • hydrogen-1 • helium-4 • oxygen-16 • none
26.1 Forces in Balance May the force be with you!
Why does the sun remain stable over time? • Inward pull of gravity balances the outward push of thermal pressure from nuclear fusion.
Question: What would happen to the sun if it began to run out of fuel? • It would become cooler very quickly. • The force of gravity would decrease. • Its core would expand as thermal pressure increased. • Its core would shrink as thermal pressure decreased.
What would happen to the sun if it began to run out of fuel? • It would become cooler very quickly. • The force of gravity would decrease. • Its core would expand as thermal pressure increased. • Its core would shrink as thermal pressure decreased.
Interior facts • The sun’s interior consists of 3 parts. • Core • Radiation zone • Convection zone • Energy moves through the sun in two main ways: • Radiation • Convection
Review of Vocabulary • Radiation zone - region of highly compressed gas where energy is transferred by the radiation.
Review of Vocabulary • Convection zone - the outer layer of the sun's interior, where energy is transferred mainly by convection currents.
26.1 The Sun’s Atmosphere Very unlike Earths!
Exterior facts • The sun's atmosphere consists of three layers. • Photosphere • Chromosphere • Corona These regions are outside the convection zone.
Photosphere • Innermost layer • Visible surface of the sun • 500 kilometers thick • Temp: approximately 5800 K
Chromosphere • Middle layer • Temp: increases to nearly 10,000 K • At high temperatures, hydrogen gas emits a reddish light. • This light gives it its name, which means “sphere of color.” • Can see this during a total solar eclipse.
Corona • Outermost layer • Gases in the corona are thin • Temp: Gases super hot (about 1 million K) • Thermal energy in it is relatively small. • Usually seen only during solar eclipses.
Sun has got a magnetic personality! • The sun's magnetic field produces striking features on and above its surface • Such as: • Sunspots • Prominences • Solar flares.
Sunspots • Areas of gas in the photosphere that are cooler than the surrounding gases. • Spots can be larger than Earth • Associated with intense magnetic fields on the sun. • Last from a few hours to a few months. • Numbers varies in cycles, with about 11 years separating one sunspot peak from the next.
Prominences • Huge loops of gas that erupt from sunspot regions. • Extend from the photo S into the chromo S and sometimes into the corona. • Travel along the magnetic field lines that connect sunspots. • Heights can be more than 100,000 kilometers above the sun's surface.
Solar Flares • Sudden release of energy • Surface erupts dramatically, producing X-rays and hurling charged particles into space. • Heat the corona to a temps near 20 million K and produce solar wind. • High-energy particles and radiation can reach Earth • Cause magnetic storms in Earth's upper atmosphere. • Storms disrupt electric power transmission, radio, TV, and phone signals.
Question: How can sunspots be recognized on the sun's surface? • Sunspots appear darker than the surrounding photosphere. • Sunspots appear lighter than the surrounding photosphere. • It is hard to distinguish sunspots from the surrounding photosphere. • Sunspots always appear in definite groups.
How can sunspots be recognized on the sun's surface? • Sunspots appear darker than the surrounding photosphere. • Sunspots appear lighter than the surrounding photosphere. • It is hard to distinguish sunspots from the surrounding photosphere. • Sunspots always appear in definite groups.
Stars • Star-a large, glowing ball of gas in space, which generates energy through nuclear fusion in its core. • the sun is the closest star to Earth
Distances • Astronomical Unit- (AU) distance from Earth to the Sun~ (150,000,000Km) • Most of Space is empty, so huge distances are required. • Light Year-distance light travels in 1 year. • Approx. 9.5 trillion Km (at 300,000 Km/s) • 1 light year=63 AU
Parallax • Apparent change in position of an object with respect to a distant background. • How we measure the distance of stars • Greater parallax=closer star • Winter to Summer
Properties of Stars • Color &Temperature • The color of a star indicates its surface temperature( think color spectrum) • Brightness • closer you are to a light the brighter it appears( not always) • Apparent brightness- brightness appears from Earth • Absolute brightness-how bright the star really is • Can be calculated using distance (if known)
Star props. cont’ • Size &Mass • Diameter can be calculated using temp, and brightness • Mass can be calculated using gravitational interactions • Composition-what is it made of
Giants and Dwarfs • Giants- large, bright stars that are smaller and fainter supergiants • White dwarfs- small dense remains of a low-medium-mass star.
26-3 Life Cycle of Stars • Stars change over their lifespan just like animals change throughout their life. • Nebula-a large cloud of gas and dust spread out over a large volume of space. • They can have different appearances bright or dark
Stars • Stars are created due to gravity. • Contacting clouds of gas/dust with enough mass to form a star are called protostars. • Stars are formed when contracting of gas/dust become so dense/hot that nuclear fusion occurs.
Adult Stars • Most of a stars life is in the main sequence on the H-R Diagram. • Mass determines how long it stays in this sequence. • More mass=brighter stars, but they use up fuel quicker.
Death of a Star • When a star runs out of fuel (Hydrogen), gravity overtakes the star. • The core cools • Temperatures rise, causing swelling on exterior. • The dwindling supply of fuel in a star’s core ultimately leads to the star’s death as a white dwarf, neutron star, or black hole.
Dying Stars • Planetary nebula-glowing cloud of gas surrounding a dying star. (low mass) • Supernova-collapse of outer layer of dying high mass star, huge explosion producing more light than the entire galaxy generates
Dying Stars • Neutron Star-remnants of high-mass star that has exploded supernova. • Spinning neutron stars that give off strong pulses of radio waves are called pulsars. • Black Hole-an object whose surface gravity is so great that even electromagnetic waves cannot escape it.
