PSU ASTRO 001 UNIT 3 EXAM QUESTIONS AND ANSWERS FULLY VERIFIED -9

A large luminosity star - ANSWER Emits more light than a low luminosity star If a red giant appears the same brightness as a red main sequence star, which one is further away? - ANSWER The red giant The heaviest nuclei of all are formed - ANSWER During a supernova explosion Hydrogen-2 + proton = ? - ANSWER Hydrogen-2 + proton = Helium-3 Why does the main sequence part of a star's life end? - ANSWER The hydrogen in the core is exhausted Many of the brightest 100 stars viewed from Earth are not on the main sequence (even though most stars are) because... - ANSWER The most luminous stars are giants and super giants that have already finished their main sequence lifetimes A 2 solar mass main sequence star is at the same distance as a 0.2 solar mass main sequence star. Which star appears brighter? - ANSWER The 2 solar mass main sequence star appears brighter The temp. of the photosphere of the Sun is closest to... - ANSWER 6,000 kelvin An estimate of the number of communicating/ technological civilizations that we expect in our galaxy would have a larger number if... - ANSWER The average number of planets that could support life for each star was larger If the Sun had twice it's mass, then which of the planets would be in it's habitable zone? - ANSWER Jupiter In the transit method of finding extrasolar planets, the distance of the planet from it's star is found from: - ANSWER Kepler's 3rd law using the period of the planet's orbit (how often a transit occurs) How do astronomers measure the temperature of stars? - ANSWER By looking at which absorption lines are present in the star's spectrum If two stars are the same temperature, how can one be more luminous than the other? - ANSWER It can have a larger radius The largest fraction of nearby stars (e.g. within 100 light years) are... - ANSWER Red main sequence stars The parallax angle of a nearby star is measured to be 0.02 arc seconds. What is the distance to the star? - ANSWER 50 parsecs Star A is 9 times more luminous than Star B. The two stars appear the same brightness. What is true about their distances? - ANSWER Star A is 3 times further away than Star B.