Table of Contents
What is the leading explanation for the existence of spiral arms?
The leading explanation for the existence of spiral arms are: passages of spiral density waves through the interstellar medium. Most of the mass of the Milky Way seems to exist in the form of: dark matter out in the Halo.
What best describes the origin of a spiral galaxy’s spiral arms?
The spiral arms contain recent star formation. What best describes the origin of a spiral galaxy’s spiral arms? The high rate of supernovae from the center of the galaxy.
Why are the spiral arms in the galaxy in the figure blue?
Sc and SBc galaxies, for instance, have very loose arms, whereas Sa and SBa galaxies have tightly wrapped arms (with reference to the Hubble sequence). Either way, spiral arms contain many young, blue stars (due to the high mass density and the high rate of star formation), which make the arms so bright.
Why are galactic spiral arms bright quizlet?
Their bright because created more readily in spiral arms because gravity bunches interstellar gas clouds more tightly in these arms than elsewhere in a galaxy’s disk. . their hot, blue stars that make the spiral arms bright. You just studied 38 terms!
Why do spiral arms exist?
Astronomers believe that galaxies have spiral arms because galaxies rotate or spin around a central axis and because of something called density waves. A spiral galaxy’s rotation, or spin, bends the waves into spirals. Stars pass through the wave as they orbit the galaxy center.
How do galactic spiral arms originate?
This indicates that the arms are the result of a persistent pattern of stars rather than particular stars causing the structures. That pattern is caused by a density (pressure) wave that spirals from the edge of the disk to the center and back out again, creating the visible spiral arms of the galaxy.
What two theories explain how the spiral arms are maintained?
First theory is the spiral density wave, this has spiral regions of alternating density, which rotate as a rigid pattern. The second theory is that spiral arms are not permanent structures, but instead are continually forming as a result of disturbances such as supernova explosions
What is a spiral galaxy best described as?
Spiral galaxies are twisted collections of stars and gas that often have beautiful shapes and are made up of hot young stars. Most spiral galaxies contain a central bulge surrounded by a flat, rotating disk of stars.
Where does a spiral galaxy come from?
Astronomers believe that a galaxy’s spiral structure originates as a density wave emanating from the galactic center. The idea is that the entire disk of a galaxy is filled with material. As this density wave passes through, it’s thought to trigger bursts of star formation.
What part of the Milky Way do the spiral arms originate from?
All spiral arms lie within the thin disk of the galaxy. They are delineated by dark dust lanes and highlighted by young, blue stars and luminous nebulae.
What explains the Milky Way’s spiral arms?
Several theories have been proposed to explain how spiral arms form. Perhaps the most intuitive of these referred to as the material arm model states that the spiral arms represent overdensities in the galaxy that have become wrapped around the galactic nucleus due to the galaxy’s rotation (see figure 2).
Why are the spiral arms of a galaxy blue?
Why are the arms of spiral galaxies typically blue in color? Stars are forming in the spiral arms so there are high mass, hot, blue stars in the arms. Collisions are much more common in large galaxy clusters. Collisions can build elliptical galaxies that are bigger and bigger.
Why do the arms of the Milky Way glow blue?
Astronomers spotted the first celestial spiral, now named the Whirlpool Galaxy, in 1845. They did so by exploiting a basic trait of spiral arms: They squeeze interstellar clouds of gas and dust, prompting them to collapse and spawn new stars. This makes spiral arms in galaxies such as the Whirlpool glow blue and pink.
Why are galactic spiral arms bright?
Spiral arms appear visually brighter because they contain both young stars and more massive and luminous stars than the rest of the galaxy. As massive stars evolve far more quickly, their demise tends to leave a darker background of fainter stars immediately behind the density waves.
Why are spiral galaxies so bright quizlet?
Why are spiral galaxies so bright? Spiral galaxies contain a lot of gas and dust, and are active areas of star formation. Since they contain many newly forming stars that are young and hot, spiral galaxies are very bright.
Why do spiral arms have a blue color quizlet?
10) Why do spiral arms have a blue color? Answer: Spiral arms are waves of enhanced density of stars and gas in the disk of a galaxy. Stars are widely separated and are not individually affected by the greater crowding in a spiral arm but gas clouds are much larger and, relatively, less widely separated.
Why are the arms of spiral galaxies typically blue in color?
The gas and dust in the arms filter out all but the blue light from stars in the arms. Stars are forming in the spiral arms so there are many more high mass, hot, blue stars. Almost all the stars of the disk are in the arms of the galaxy and their light makes it appear blue.
Why do the spiral arms continue to exist?
How the spiral arms form continues to puzzle scientists. One theory suggests the galaxy arms could be the result of density waves traveling through the outer disk. Encounters between galaxies could cause such waves as the mass of the smaller galaxy could affect the structure of the larger galaxy as the two combine.
What is the reason that spiral arms are prominent in spiral galaxies?
Because arms wind up with time, a galaxy’s arms will look tighter or looser depending on which population of stars astronomers observe. The reason we can see this spiral pattern is because as it passes through the galaxy the density wave compresses gas clouds, triggering star formation
Why are spiral arms places of active star formation?
The stars and gas and dust clouds in the disk congregate in a spiral pattern. Star formation occurs in the spiral arms because the gas clouds are compressed in the arms to form stars. The very luminous, short-lived O and B-stars and H II regions around them enhance the spiral outline.
Are spiral arms permanent?
Grand design spirals have long, narrow, well defined arms, while those galaxies with short, fragmented arms are termed flocculent spirals. That spiral arms still exist indicates that they are not rigid nor permanent structures
Where do the arms of a spiral galaxy come from?
Here is their response: Most spiral arms in galaxies are density waves, which are compression waves (like sound) that travel through the disk and cause a piling-up of stars and gas at the crest.
How does a spiral bar galaxy form?
Bars form when stellar orbits in a spiral galaxy become unstable and deviate from a circular path. The bar becomes even stronger as it locks more and more of these elongated orbits into place. Eventually a high fraction of the stars in the galaxy’s inner region join the bar.
What makes up the spiral arms of the Milky Way galaxy?
Many don’t realize that galaxies like the Milky Way actually have spiral arms. These are pinwheels within the galaxy that are made up of stars, planets, asteroids and hydrogen clouds that reach out from the center of the galaxy to its edges.
What is the current theory for spiral arm formation?
The Spiral Density Wave Theory Basically, this theory states that the spiral arms of a disk galaxy are regions of the galaxy that are of higher density; and so we call them density waves. They are also areas that are moving more slowly than the galaxy’s stars and gas.
