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Ch 23 Milky Way Pt 1
Vocabulary
| Term | Definition |
|---|---|
| Galaxy | gravitationally bound collection of an extremely large number of stars |
| Milky Way | spiral galaxy in which the Sun resides; the galaxy's disk is visible as a faint band of light |
| Interstellar Matter | gas and dust between stars intermixed throughout all of space |
| Andromeda Galaxy | nearest major galaxy to the Milky Way |
| Spiral Galaxy | composed of a flattened, star-forming disk, which may have spiral arms & a galactic bulge |
| William Herschel | suggested that the Milky Way was a disk-shaped galaxy with the Sun at its center (incorrect) |
| Variable Star | star whose luminosity changes over time |
| Pulsating Variable Star | star whose luminosity varies in a predictable, periodic way |
| Nova | star that suddenly increases in brightness then slowly fades back to its original luminosity |
| Supernova | explosive death of a star (usually high-mass) |
| Cataclysmic Variable | collective name for a novae or supernovae |
| Intrinsic Variable | star that varies in appearance due to internal processes rather than external |
| RR Lyrae Variable | variable star whose luminosity typically changes in a period of less than a single day |
| Cepheid Variable | variable star whose luminosity changes over a period that is longer than a single day |
| Luminosity Curve | expresses the product of relative spectral energy distribution by its visibility |
| Instability Strip | region of the H-R diagram where pulsating post-main-sequence stars are found |
| Period-Luminosity Relation | allows the distance of a Cepheid variable star to be determined |
| Pulsation Period | time for a variable star's change in luminosity to complete one full cycle |
| Cosmic Distance Ladder | collection of techniques used to indirectly measure distances in the universe |
| Globular Cluster | tightly bound, spherical collection of hundreds of thousands, or millions, of stars |
| Harvard Computers | team of skilled women who processed astronomical data in the early 20th century |
| Leavitt | Harvard computer who discovered the period-luminosity relationship for measuring distances |
| Cannon | Harvard computer who devised the stellar spectra classification system we still use today (OBAFGKM) |
| Shapley | accurately estimated the size of the Milky Way galaxy and the Sun's position within it |
| Shapley-Curtis Debate | (The Great Debate) Shapley argued the MW was the only galaxy, unlike Curtis |
Created by:
john_bailey720
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