PSU Astro 001 Unit 3 Exam

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PSU Astro 001 Unit 3 Exam A large luminosity star - ✔✔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 aw... ay? - ✔✔The red giant The heaviest nuclei of all are formed - ✔✔During a supernova explosion Hydrogen-2 + proton = ? - ✔✔Hydrogen-2 + proton = Helium-3 Why does the main sequence part of a star's life end? - ✔✔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... - ✔✔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? - ✔✔The 2 solar mass main sequence star appears brighter The temp. of the photosphere of the Sun is closest to... - ✔✔6,000 kelvin An estimate of the number of communicating/ technological civilizations that we expect in our galaxy would have a larger number if... - ✔✔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? - ✔✔Jupiter In the transit method of finding extrasolar planets, the distance of the planet from it's star is found from: - ✔✔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? - ✔✔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? - ✔✔It can have a larger radius The largest fraction of nearby stars (e.g. within 100 light years) are... - ✔✔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? - ✔✔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? - ✔✔Star A is 3 times further away than Star B. What is the name of the slightly cooler layer of the Sun just outside the photosphere? - ✔✔Chromosphere How does a star move on the H-R diagram during the period of time it is converting hydrogen to helium in it's core? - ✔✔It remains at a certain point on the main sequence and does not move in the H-R diagram If the entire mass of Earth were concentrated in a region the size of a marble, the resulting object would be... - ✔✔A black hole How does the habitable zone change depending on the mass of a star? - ✔✔A more massive star has a habitable zone father from the star. Habitable zone - ✔✔Region around a star where liquid water could be present on a planet's surface If a star begins with less than (<) 8 solar masses... - ✔✔Core becomes White dwarf If a star begins with 8-40 solar masses... - ✔✔Core becomes neutron star If a star begins with greater than (>) 40 solar masses... - ✔✔Becomes black hole Drake equation - ✔✔Method to estimate the number (N) of communicating/ technological civilizations in our galaxy The sun is made up of... - ✔✔73% hydrogen and 25% helium Suns core - ✔✔High density and temperature, nuclear reactions occur, gamma rays produces Suns radiative zone - ✔✔Photons are reabsiebed and emitted, energy of photon can take 170,000yrs to pass through Convective zone - ✔✔Hot gas rises as cold gas sinks, light traverses in 1 week 99% of the solar systems mass is in... - ✔✔The sun Luminosity - ✔✔The absolute power output at the source Brightness - ✔✔The apparent output as observed at some distance Suns corona - ✔✔Low density, temp 1 million k, visible during solar eclipse Chromosphere - ✔✔Red or orange, we see through this to the photosphere Brightest nighttime star - ✔✔Sirius, "Dog Star", 2x size of sun Nearest star - ✔✔Alpha Centauri, 4.3 light years from the sun Cooler stars are colored - ✔✔Red Hotter stars are colored - ✔✔Blue On the H-R diagram, the horizontal axis is - ✔✔Surface temperature, increasing to the left The h-r diagram temps are measured using... - ✔✔The spectral class Spectral classes of stars, from hotter to cooler... - ✔✔OBAFGKM "oh, be a fine guy, kiss me!" Vertical axis on the H-R diagram - ✔✔Luminosity, increasing to the top For main sequence stars, higher temps mean... - ✔✔Greater lumosity Main sequence stars are located on the H-R diagram... - ✔✔In a band from lower right to upper left Red dwarfs on the H-R diagram are located - ✔✔Lower right because they're cool, faint, and small Blue giants are on the H-R diagram are located... - ✔✔Upper left because they're hot, bright, and large Red giants and super giants - ✔✔Burning helium and no longer hydrogen, starting to die White dwarfs - ✔✔Hot, small, dim, dying stars More massive stars live - ✔✔Few million years, because bigger stars use their fuel faster Less massive stars live - ✔✔Much more than 14 billion years, little stars live longer than big stars First extrasolar planets discovered in 1992 by - ✔✔PSU prof Alex Wolszczan Thousands of extra solar planets were found during Kepler mission using... - ✔✔The transit method, the brightness of the star decreases due to the planet passing right in front of it If Star A is a more massive main sequence star than Star B, and Star A appears fainter, which star is further away? - ✔✔Star A, because it is more luminous and would not appear fainter unless it was much farther away [Show More]

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