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50 Cards in this Set
- Front
- Back
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What are the characteristics of stars?
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- Colour
- Temperature - Size - Mass - Luminosity - Spectral Type - The relationships between these characteristics and the H-R Diagram |
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What is colour?
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Stars appear to be exclusively white at first glance. But if we look carefully, we can notice a range of colors: blue, white, red, and even gold. Cool stars (Type K and M) radiate most of their energy in the red and infrared region of the electromagnetic spectrum and thus appear red, while hot stars (Type O and B) emit mostly at blue and ultra-violet wavelengths, making them appear blue or white.
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What is temperature?
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The degree or intensity of heat present in a substance or object. The color of stars depends on their temperature. The coolest stars will look red, while the hottest stars will appear blue.
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What is size?
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Size is a measure of how large something is in volume.
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What is mass?
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Mass is a measure of how much matter is packed into something.
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What is luminosity?
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The luminosity of a star is the amount of light it emits from its surface.
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What is spectral type?
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A category for classifying a star according to features of its spectrum that indicate its surface temperature and chemical composition.
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What is the H-R Diagram?
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The Hertzsprung–Russell diagram is a scatter graph of stars showing the relationship between the stars' absolute magnitudes or luminosities versus their spectral types or classifications and effective temperatures.
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How is a star born?
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Stars are formed in nebulae (stellar clouds of dust and gas - mostly hydrogen). In these nebulae, dense parts of these clouds undergo gravitational collapse and compress to form a rotating gas globule. The globule is cooled by emitting radio waves and infrared radiation then it is compressed by GF. These forces cause the roughly-spherical globule to collapse and rotate. The process of collapse takes from between 10,000 - 1,000,000 years. As the collapse proceeds, the temperature and pressure within the globule increases, as the atoms are in closer proximity and the globule rotates faster. This spinning causes an increase in centrifugal forces (a radial force on spinning objects) that causes the globule to have a central core and a surrounding flattened disk of dust (called a protoplanetary disk or accretion disk). The central core becomes the star; the protoplanetary disk may eventually coalesce into orbiting planets, asteroids, etc. The contracting cloud heats up due to friction and forms a glowing protostar; this stage lasts for roughly 50 million years. If there is enough material in the protostar, the gravitational collapse and the heating continue. If there is not enough material in the protostar, one possible outcome is a brown dwarf.
When a temperature of about 27,000,000°F is reached, nuclear fusion begins. This is the nuclear reaction in which hydrogen atoms are converted to helium atoms plus energy. This energy (radiation) production prevents further contraction of the star. Young stars emit jets of intense radiation that heat the surrounding matter to the point at which it glows brightly. The protostar is now a stable main sequence star which will remain in this state for about 10 billion years. After that, the hydrogen fuel is used up and the star begins to die. |
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What are the possible deaths of a star?
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A star will become either a black dwarf, neutron star, or black hole, depending on how massive it was.
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Describe the planet Mercury.
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Mercury is the closest planet to the sun. Its cratered surface can reach upwards of 800 degrees fahrenheit because of its proximity to the sun and its slow rotation. Only slightly larger than Earth's moon, it is the smallest planet in the solar system. It has no moons, no rings, and a very thin atmosphere.
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Describe the planet Venus.
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The second planet from the sun, Venus, is slightly smaller than Earth. Because of its relative proximity to Earth, it is the largest planet seen in the night sky. The cratered surface of the planet is hot, with surface temperatures around 900 degrees fahrenheit. Venus has a thick atmosphere of sulfuric acid and carbon dioxide. The density of its atmosphere makes the air pressure 90 times that of Earth's. This makes the planet decidedly inhospitable to life.
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Describe the planet Earth.
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Earth, the third planet from the sun and the largest terrestrial planet, is the only planet known to have living beings and the only one with liquid water on its surface. The atmosphere made of mostly nitrogen, oxygen and carbon dioxide is crucial to Earth's ability to support life. The surface of the earth is mostly water, but with large landmasses and a stunning variety of different ecosystems.
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Describe the planet Mars.
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Mars, also called the Red Planet, is the solar system's fourth planet. Its surface is characterized by dust storms, large volcanoes and deep valleys. The red color of the surface comes from iron oxide or rust in the soil. Some of the surface features of Mars, such as dry river beds, hint toward water previously existing on the planet. The atmosphere is very thin on Mars, with only 1/100th the air pressure of Earth, and the planet is relatively cold with surface temperatures ranging from -171 to 32 degrees fahrenheit.
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Describe the planet Jupiter.
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Further from the sun, past a ring of asteroids, lies the largest planet in our solar system -- Jupiter -- the first of the gas giant planets. Its characteristic colored cloud patterns are caused by enormous, swirling storms in its atmosphere. The largest and most distinctive of these, the Great Red Spot, is large enough to swallow Earth. The interior of this great planet is mostly hydrogen and helium. Jupiter has 63 moons and a faint ring system.
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Describe the planet Saturn.
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Saturn, the sixth planet from the sun and the second gas giant, is unique in that an extensive and complex set of rings orbit the planet in a thin band. Saturn is large -- about 9.5 times the radius of Earth. It has 62 moons in its orbit. The interior of Saturn, like Jupiter, is made of mostly hydrogen and helium in liquid form because of the strong pressure there.
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Describe the planet Uranus.
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While most planets spin on their axis with a slight tilt, the gas giant Uranus spins on a plane with the orbit of the sun. This creates unique seasonal changes. This cold planet is four times the diameter of Earth, and is made of a large atmosphere of methane with a dense core of frozen methane. Uranus has a faint ring system and 27 moons in its orbit.
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Describe the planet Neptune.
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The blue planet Neptune is the farthest from the sun and, like Uranus, is a very cold place. Because of its distance from the sun, one year on Neptune is 165 Earth years. The large amount of methane in the atmosphere gives the planet its blue color, and the cold interior of the planet is mainly methane ice. It is a relatively large planet. Also like Uranus, it has a diameter roughly four times that of Earth. Thirteen moons and a faint ring system orbit the planet.
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What is a Moon?
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A natural satellite of a planet.
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What are the two Moon's of Mars?
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Mars has two known moons, Phobos and Deimos, which are thought to be captured asteroids.
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What is the Asteroid Belt?
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The asteroid belt is a doughnut-shaped concentration of asteroids orbiting the Sun between the orbits of Mars and Jupiter.
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Describe the Dwarf Planet Pluto.
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Pluto is a dwarf planet (or plutoid) - it was classified as a dwarf planet in 2006; before that it was considered to be the smallest planet in our solar system. Pluto is smaller than a lot of the other planets' moons, including our moon.
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What is the Kuiper Belt?
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The Kuiper belt is a region beyond the planet Neptune in which at least 70,000 small, icy, slow-moving objects orbit.
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What are Comets?
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A comet is a small, icy celestial body that orbits around the sun. It is made up of a nucleus (solid, frozen ice, gas and dust), a gaseous coma (water vapor, CO2, and other gases) and a long tail (made of dust and ionized gases). The tail develops when the comet is near the Sun.
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What is a Nebular?
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A cloud of gas and dust in outer space.
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What is a Star?
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A ball of mostly hydrogen and helium gas that shines extremely brightly. A star is so massive that its core is extremely dense and hot. At the high core temperatures of a star, atoms move so fast that they sometimes stick to other atoms when they collide with them, forming more massive atoms and releasing a great amount of energy. This process is known as nuclear fusion.
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What is a Red Giant Star?
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A red giant is a relatively old star whose diameter is about 100 times bigger than it was originally, and had become cooler (the surface temperature is under 6,500 K). They are frequently orange in colour. It is about 20 times as massive as the Sun about 14,000 times brighter than the Sun.
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What is a Red Dwarf Star?
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A red dwarf is a small, cool, very faint, main sequence star whose surface temperature is under about 4,000 K. Red dwarfs are the most common type of star.
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What is a White Dwarf Star?
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A white dwarf is a small, very dense, hot star that is made mostly of carbon. These faint stars are what remains after a red giant star loses its outer layers and their nuclear cores are depleted. They are about the size of the Earth (but much heavier). They will eventually lose their heat and become a cold, dark black dwarf.
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What is a Supernova?
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When huge stars grow old their core fuses all the hydrogen into helium. Their core shrinks, becoming hotter and denser. With these changes, fusion now produces heavier elements (this temporarily stop the core's shrinking). Then the core collapses (instantly). As the iron atoms are crushed together in this gravitational collapse, the core temp rises to about 100 billion degrees. The electrical forces between the atoms' nuclei overcomes the gravitational forces, causing a massive, bright, short explosion called a supernova. Shock waves, blow away the star's outer layers.
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What is a Supergiant Star?
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A supergiant is the largest known type of star; some are almost as large as our entire solar system. Betelgeuse and Rigel are supergiants. These stars are rare. When supergiants die they supernova and become black holes.
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What is a Black Dwarf Star?
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A black dwarf is a white dwarf that has cooled down to the temperature of the cosmic microwave background, and so is invisible.
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What is a Neutron Star?
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A neutron star is a very small, super-dense star which is composed mostly of tightly-packed neutrons. This hard-to-see body has a thin atmosphere of superhot hydrogen plasma and a crust. Neutron stars are formed from supernova explosions.
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What is a Black Hole?
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A black hole is a massive object (or region) in space that is so dense that within a certain radius, its gravitational field does not let anything escape from it, not even light.
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What is the brightness of a star?
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Apparent Brightness is how bright the star appears to a detector on Earth.
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What is the difference between the Apparent Brightness of a star and its Luminosity?
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The difference between luminosity and apparent brightness depends on distance. Luminosity is a property of the star, so everyone who has some means of measuring it's luminosity should find the same value. But apparent brightness depends on your location, so everyone will measure a different brightness for the same star if they are different distances away from the star.
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List the Spectral Classes in order of surface temperature (hottest to coolest).
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O B A F G K M.
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What is a Protostar?
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A protostar is a young star which is in the early stages of formation, before it reaches the main sequence stage.
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What is the life cycle of a Sun-Like Star?
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(Mass under 1.5 times the mass of the Sun) --> Red Giant --> Planetary Nebula -->White Dwarf --> Black Dwarf
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What is the life cycle of a Huge Star?
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(Mass between 1.5 to 3 times the mass of the Sun) --> Red SuperGiant --> Supernova --> Neutron Star
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What is the life cycle of a Giant Star?
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Giant Stars (Mass over 3 times the mass of the Sun) --> Red SuperGiant --> Supernova --> Black Hole
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What are the inner planets?
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The inner planets are: Mercury, Venus, Earth, and Mars. They are relatively small, composed mostly of rock, and have few or no moons.
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What are the outer planets?
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The outer planets include: Jupiter, Saturn, Uranus, Neptune, and Pluto (a dwarf planet). They are mostly huge, mostly gaseous, ringed, and have many moons (again, the exception is Pluto, the dwarf planet, which is small, rocky, and has four moons).
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What is Stellar Wind?
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Stellar wind is ionized gas that is ejected from the surface of a star (including the Sun). Older (evolved) stars give off stronger stellar winds than younger stars.
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What is a Yellow Dwarf?
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Yellow dwarfs are small, main sequence stars. The Sun is a yellow dwarf.
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What is a pulsar?
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A pulsar is a rapidly spinning neutron star that emits energy in pulses.
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What is a Brown Dwarf?
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A brown dwarf is a "star" whose mass is too small to have nuclear fusion occur at its core (the temperature and pressure at its core are insufficient for fusion). A brown dwarf is not very luminous.
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What is the Nebula Theory?
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The nebular hypothesis is the most widely accepted model explaining the formation and evolution of the Solar System.
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How do planets begin to formed?
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Planets are formed out of the remnants of star birth. When a star is still in the initial stages of being created, the molecular cloud surrounding it begins to rotate. As it rotates, the cloud will begin to condense around areas where there is more matter. Local concentrations of mass known as planetesimals form, and these accelerate the accretion process by drawing in additional material by their gravitational attraction. These concentrations become ever denser until they collapse inward under gravity to form protoplanets.
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What happens to protoplanets after they are formed?
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The protoplanets formed in this way will become asteroids, comets, moons and planets, depending on their size. Most will collide with each other to form a small number of planets, and those which don’t actually collide will become satellites of the larger planets.
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