What are the two main instrinsic observable properties that astronomers use to classify stars?
A. Distance and position on the sky; B. Mass and Radius; C. Central Temperature and Pressure; D. Surface Temperature and Luminosity; E. Age and composition. • Which of the following is false? The stars in a star cluster have almost the same: A. Position on the sky; B. Distance; C. Age; D. Initial composition; E. Mass. • If you put the Pleiades 2 times further away, the stars would appear: A. the same apparent brightness; B. 1/2 as bright; C. 1/4 as bright; D. 1/8 as bright; E. 1/16 as bright. Th 2005 Sep 22: • Suppose you observe a binary star consisting of two identical main sequence stars that are too close to resolve in a telescope (they appear as a single point of light. Where does the binary appear? A. On the main sequence; B. Above the main sequence; C. Below the main sequence; D. As a supergiant. T 2005 Sep 27: • We know that the Orion nebula is a star-forming region (a region containing stars that are much younger than the 14 billion year age of the Universe) because: A. It con
