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58 Cards in this Set
- Front
- Back
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Our Milky Way is a great disk made of stars orbiting a ____ ____ in the disk.
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Central point.
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Variable stars are... That pulsate in brightness because...
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Stars in the giant branch of the HR diagram. They pulsate in brightness because of the expansion and contraction of their outer layers.
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Pulasion period is...
The longer the pulsation; |
The time between a star's brightenings. THE GREATER THE LUMINOSITY
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An RR Lyrae variable is...
Generally has the same luminosity regardless of... |
A start with a pulsation period ranging from 1.5 hours to 1 day. PULSATION PERIOD LENGTH
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The Nucleus or the Galactic Center is a region of... Much of which is obscured by...
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Very high star density that globular clusters orbit. INTERSTELLAR GAS/DUST
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The halo is... And contains...
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A spherical region where globular clusters are located... 90% of galaxy's mass.
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Approximately how many times has the Sun orbited our galaxy?
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20.
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How many stars does the galaxy contain within its disk?
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100 billion.
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Dark matter is...
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Matter outside of the disk of the galaxy.
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Where does dark matter extend to?
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Other galaxies and the universe as a whole.
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Sagittarius A* is... (2)
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The center of the galaxy, and a supermassive black hole.
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In globular cluster stars, stars can exist with what percentage of simply hydrogen and helium?
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99.9%
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Population 1 stars are...
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Stars in the disk and arms that have small amounts of heavy elements.
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Population 2 stars are...
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Stars in the halo and bulge that contain only traces of heavy elements.
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Why do Population 1 stars contain greater amounts of heavy elements?
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Because they formed from gas that had been enriched by previous generations of massive stars.
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What creates spiral arms?
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Gravitational tugs and supernovae.
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Spiral density waves are...
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Alternating dense and less-dense regions that are frozen in place and rotate as a rigid pattern.
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Spiral galaxies can be defined as...
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The disklike galaxies with spiral arms.
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Barred spiral galaxies have... [Name the abbreviation.]
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An elongated central bar from which the spiral arms extend. SB
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Normal spiral galaxies...
[Name the abbreviation.] |
Do not have bars. S
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In describing galaxies, the variable A stands for...
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Tightly wound arms, and a large bright nucleus
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In describing galaxies, the variable C stands for...
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Loosely wound arms and a small, dim nucleus
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In describing galaxies, the variable B stands for...
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Characteristics between A & C variables.
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S0 galaxies are galaxies with... (2)
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Flat disks that have spiral arms; band of dark dust crossing the nuclear bulge.
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Elliptical galaxies are...
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Galaxies that are not flattened into disks and do not have spiral arms.
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How are elliptical galaxies divided?
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Into the ratios of their major and minor axes.
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As the numbers of an elliptical galaxy get larger (E0-E7)...
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They become more of an elongated elliptical.
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Irregular galaxies have...
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No distinct shape.
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What forms when galaxies collide?
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Galaxies with irregular shapes or more than one nucleus.
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Superclusters are... In size...?
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Gigantic threadlike or sheetlike clusters of galaxies that are hundreds of millions of lightyears in size.
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The redshift of a galaxy depends on...
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Its distance from Earth.
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The farther away a galaxy is...
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The faster it is moving away.
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In uniformal expansion, ALL points are... And NO points are...
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Moving away from other points.
At the center. |
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The Hubble constant is...
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The missing variable in the equation of the Rate of Universal expansion.
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The Hubble constant is predicted to be...
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70 kilometers per second per megaparsec.
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Radio galaxies are...
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Galaxies that emit as much or more energy in the form of radio wavelengths as visible light.
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An active galactic nucleus is... What is located here?
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A galaxy's core;
Highly energetic objects or activities. |
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Name the galaxy types in smallest to largest.
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Dwarf ellipticals, large spirals, giant ellipticals.
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Quasars are... And have spectal lines of (such as)...
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Starlike objects with emission lines in their spectra;
Common elements - Hydrogen. |
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In radio galaxies, there are... What are these probably created by?
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JETS of ions;
Magnetic forces. |
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Cosmology is the study of...
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The universe; its current nature, and its origin/evolution.
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The Big Bang theory states that...
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The universe began as a point and has been expanding ever since.
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The Steady-State theory proposes that the universe looks...
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The same on large scales to all observers, and that it has always looked that way.
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Cosmic background radiation is...
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Weak radiation that is left over from the early, hot stages of the Big Bang Theory.
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In an open universe...
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Expansion will never stop.
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IN a closed universe...
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The expansion will stop and turn into a closed universe.
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In a flat universe...
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The expansion will slow to a halt in a infinite amount of time, but will never contract.
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All 3 possible outcomes for the universe are based on the fact that...
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Expansion has slowed since the beginning of the universe.
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The average density of matter is...
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The total amount of matter in the universe.
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Critical density is...
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The dividing point between an opened or closed universe.
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The inflationary universe is a model that predicts...
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That the universe is flat.
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Stars tend to be older in what type of galaxies?
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Elliptical.
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Which is the least common form of a galaxy?
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Irregular.
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Which form of magnitude defines the actual amount of light a star gives off?
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Absolute.
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What is the range of temperatures for stars?
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1000° to 100,000°
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What is the acronym for the color spectrum?
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ROYGBIV
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Where in the Millky Way are new stars being formed?
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In the spiral arms.
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What are the oldest objects in the milky way?
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Globular clusters.
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