What does density wave theory explain?
Density wave theory or the Lin–Shu density wave theory is a theory proposed by C.C. The presence of spiral density waves in galaxies has implications on the star formation, since the gas orbiting around the galaxy may be compressed and form shock periodically.
How does the density wave model explain why so much star formation takes place in spiral arms?
Faster-moving gas clouds inevitably overtake these slowly moving density waves. As they do so, these gas clouds get squeezed by the regions of higher density. This triggers star formation as the gas clouds collapse, and this new star formation lights up the spiral arms with a lot of light!
What is a density wave and how is it defined?
[′den·səd·ē ‚wāv] (physics) A sound wave or other type of material wave which causes the density of the matter through which it passes to alternately rise above and drop below its mean value.
What is the density wave model?
One of the more successful models developed to explain the origin of spiral arms in galaxies is the density wave model. In this model, spiral arms are regions of the thin disk that are denser than average, and move around the galaxy more slowly than the individual stars and interstellar material. …
What causes density waves?
“Density waves have many possible origins. A large central bar, such as is seen in NGC 1300, may drive a two-arm density wave for a relatively long time, eventually causing the gas in the outer disk to move outward and wrap into a giant ring at the edge of the galaxy’s disk.
What is the density wave model quizlet?
Density wave theory. A model for spiral galaxies that proposes that the arms are the result of density waves sweeping around the galaxy. • A density wave is a wave in which areas of high and low pressure move through the medium. lThe stars revolve around the Galaxy independent of the spiral arms.
What is the relationship between density and wave speed?
Since the speed of a wave on a string is inversely proportional to the square root of the linear mass density, the speed would be higher in the low linear mass density of the string.
What is the most likely range of values for Hubble’s constant what are the uncertainties in its value?
We review the observational determinations of the Hubble constant which have been made in recent years. We conclude that the most likely value of Ho is 58 km S-l Mpc-1 with uncertainties of + 10 and – 5. Thus the age of the standard big bang model is 11.2 Gyr.
What is the difference between an emission and a reflection nebula quizlet?
Reflection nebula: only glow because they are reflecting light from a nearby star because it is made mostly of dust. Emission nebula: glow due to being blasted by light and radiation from a nearby massive star.
What is the difference between a flocculent spiral galaxy and a grand design spiral galaxy?
A grand design spiral galaxy (like Whirlpool Galaxy) has prominent and well defined spiral arms, whereas a flocculent galaxy (like Sunflower Galaxy) has short segments of spiral structure, “fluffy” in appearance, but without the dramatic well defined spiral arms of a grand design spiral.
How does density relate to wave?
The density of a material affects the speed that a wave will be transmitted through it. In general, the denser the transparent material, the more slowly light travels through it. A light ray speeds up as it passes from glass into air, and bends away from the normal.
How does density affect wavelength?
As waves travel into the denser medium, they slow down and wavelength decreases. Part of the wave travels faster for longer causing the wave to turn. The wave is slower but the wavelength is shorter meaning frequency remains the same.
What was the purpose of the density wave theory?
Density wave theory or the Lin-Shu density wave theory is a theory proposed by C.C. Lin and Frank Shu in the mid-1960s to explain the spiral arm structure of spiral galaxies.
How are spiral arms explained in density wave theory?
Lesson Summary. The existence of spiral arms in a spiral galaxy can be explained, in part, by the spiral density wave theory, the theory that tries to explain the spiral arms of disk galaxies. In essence, this theory says that a galaxy’s density waves are its spiral arms, and they are regions of increased density moving slowly through space.
How are density waves related to star formation?
Density waves have also been described as pressurizing gas clouds and thereby catalyzing star formation. Beginning in the late 1970s, Peter Goldreich, Frank Shu, and others applied density wave theory to the rings of Saturn.
How are density waves related to traffic jams?
The cars move through the traffic jam: the density of cars increases in the middle of it. The traffic jam itself, however, moves more slowly. In the galaxy, stars, gas, dust, and other components move through the density waves, are compressed, and then move out of them.