Details Title: ASTRONOMY CHAPTER 9 Description: from book and outline paper Total Flash Cards: 43 Created: 04/01/2009 19:25:45		New Users: To study from this flashcard set, or to create your own your own study flash cards, REGISTER HERE. Existing Users: CLICK HERE. Additional Astronomy Flashcards
Cards in this set: Term What is the appearance of a star shifting as Earth changes its position called? Definition Trigonometric Parallex Term How many lightyears does one parsec equal? Definition 3.26 Term We can't use a parallex to measure up to more than how many parsecs? Definition 50 Term What is the continuous motion of stars due to their motion through the milky way known as? Definition proper motion Term The more distant a light source is, does it appear brighter or fainter? Definition fainter Term How many times more brighter is Rigel than Betelguese? How many times further away is Rigel from Betelguese? Definition 3.3 brighter, 1.6 times further Term What is absolute magnitude? Definition the magnitude of a star if it were 10 pc away Term We can find a stars distance by comparing what two things?? Definition absolute magnitude and apparent magnitude Term Brightness increases with what? Definition size Term Are hotter stars brighter or fainter? Definition brighter Term What does the Hertzsprung-Russell diagram order the stars in a diagram of? Definition luminosity vs. temperature Term Where are most stars found in the H-R Diagram? Definition the main sequence Term Where do cooler stars lie on the H-R diagram? hotter stars? brighter stars? fainter stars? Definition cooler: right hotter: left brighter: top fainter: bottom Term Where do stars spend most of their active lifetime on the H-R diagram? Definition main sequence Term on H-R Diagram, what does blue and red indicate? Definition temperture. Red is cold, blue is hot Term What lumonisty class do main sequence stars belong to? Definition class V (five) Term What are binary stars? Definition pairs of stars that orbit their common center of mass Term What is the center of mass known as? Definition the balance point of the system Term Does the center of mass shift towards the more or less massive star? Definition more Term What can we use the Doppler shifts to measure? Definition the seperation of spectroscopic binaries Term What is a doppler shift? Definition measurement of radial velocities Term What are binaries that have a double-dip light curve known as? Definition eclipsing binaries Term When studying the light curve, when does the larger dip occur? Definition when the cooler star moves behind the other Term The higher a stars mass, the brighter or fainter it is? Definition brighter Term Do higher masses have shorter or longer lives? Definition shorter Term What are the most common stars? Definition faint, red dwarves Term What groups are higher mass stars in? lower mass? Definition higher mass: OBA lower mass: FGKM Term What happens the parallex angle with stars that are farther away? Definition the smaller the angle is Term What is luminosity? Definition absolute brightness (intrinsic brightness); it's a measure of total power radiated from a star Term What is apparent brightness? Definition how bright a star appears from earth Term What happens to the star if the magnitude is smaller? Definition the star is brighter Term What are the five luminosity classes? Definition 1a. Bright supergiants 1b. supergiants 2. Bright giants 3. Giants 4. Sub-giants 5. main-sequence stars Term What characteristic of a star do you need to find in order to find luminosity, diameter, and mass? Definition distance Term What can astronomers observe to measure the distance of nearer stars? Definition stellar parallexes Term What are stellar distances expressed in? Definition parsacs Term What is the distance modulus related to? Definition the distance to the star Term What two types of stars lie above the main sequence? why? Definition giants and supergiants, because they're larger Term What is one way to assign stars to luminosity classes? Definition the widths of their spectral lines Term What can be found in the orbits of visual binary system stars? Definition shape, size and period Term What is the difference between a visual binary system and eclipsing binary system? Definition visual binary: visible seperately eclipsing Binary: not visible seperatly Term What two characteristics of stars can astronomers find through the eclipsing binary system? Definition masses and diameters Term With the mass and diameter, what can you determine? Definition a stars average density Term What does the mass-luminosity relation rule state? Definition the more massive a star, the more luminous it is