Download Stellar Astronomy Unit 3 Key Terms and Matching Definitions _____

Stellar Astronomy Unit 3
Key Terms and Matching Definitions
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21-cm radiation
AGN
barred spiral
Cepheid variable
dark matter
Edwin Hubble
elliptical galaxy
galactic cannibalism
galactic merger
galaxy
galaxy cluster
Local Group
Milky Way Galaxy
nebula
redshift
Sag A*
spiral galaxy
1. Our home galaxy.
2. A cloud of interstellar gas and dust. What early astronomers
thought distant galaxies were.
3. Stars that pulsate at a rate proportional to their luminosity.
They are used to determine the distance to galaxies outside our
own Milky Way.
4. Radiation from hydrogen that has been used to map the
structure of the Milky Way.
5. A radio source thought to be at the center of our galaxy.
6. Unseen matter that likely accounts for the rotation of our
galaxy and others as though they are solid disks with the inner
stars rotating at the same rate as the outer stars.
7. A flattened galaxy reminiscent of a pinwheel.
8. An oval galaxy with no distinguishing spiral arms.
9. A collection of galaxies held together by their mutual gravitational attraction.
10. The collection of approximately 40 galaxies that includes the Milky Way Galaxy.
11. When two similarly-sized galaxies collide and merge together into one larger galaxy.
12. When a small galaxy collides with a large galaxy and is “swallowed up” by the larger one.
13. When spectral lines move to longer wavelengths as a result of a galaxy moving away from us. Used
to determining the speed of a receding galaxy.
14. The astronomer who first determined that most galaxies are moving away from us, indicating an
expanding universe.
15. An active galactic nuclei where matter is likely spiraling into a central black hole, generating
energetic electromagnetic radiation that we can observe.
16. A spiral galaxy with a bar of star through its center.
17. A large collection of stars, nebulae, interstellar gas and dust.