Astro 1 Unit 4

Astro 1 Unit 4 What are the differences between open star clusters and globular star clusters? - ✔✔Open clusters are less concentrated, younger, and have fewer stars Which of the following is FALSE? - ✔✔A nova is more ...

Astro 1 Unit 4 What are the differences between open star clusters and globular star clusters? - ✔✔Open clusters are less concentrated, younger, and have fewer stars Which of the following is FALSE? - ✔✔A nova is more luminous than a supernova What kind of a gas cloud can collapse and form stars? - ✔✔The gas cloud must have a mass that exceeds the Jeans mass so that gravity overcomes the internal pressure in the cloud What is the mass of the black hole at the center of the Milky Way? - ✔✔4 million solar masses How do you measure the mass of the supermassive black hole at the center of the Milky Way? - ✔✔Look at the orbits of nearby stars and apply Kepler's third law About how long does it take light to cross the Milky Way galaxy? - ✔✔About 100,000 years What does our galaxy look like? - ✔✔It has a large disk with spiral arms, and is relatively flat and thin It has clouds of gas and dust in the spiral arms Older yellow stars are found mostly in the central bulge Old stars and globular clusters are located in a spherical halo above and below the disk Why do stars in the halo of the galaxy have almost no heavy elements such as carbon, nitrogen, and oxygen? - ✔✔Halo stars formed before those elements were made Where do stars form in the galaxy today? - ✔✔In the disk Where are open clusters found? - ✔✔In the disk In the symbol for the Hubble type of a galaxy, SBc, the "B" denotes: - ✔✔The presence of a bar What happens to the planets in a galaxy when that galaxy collides with another galaxy? - ✔✔Nothing, because the spaces between stellar systems in a galaxy is much larger than their size Which properties of spiral galaxies allows us to sub classify them as Sa, Sb, or Sc? - ✔✔Size of bulge and extent of spiral arms Compared to spiral galaxies, elliptical galaxies have: - ✔✔Less gas, redder colors, and less new star formation What is the difference between an E0 and an E7 gas? - ✔✔The E7 has an oval shape and the E0 is circular You will see that the universe is almost 14 billion years old. That means that we see the most distant galaxies as they were when the universe was: - ✔✔1-2 billion years old According to models of galaxy formation, which population of stars formed first? - ✔✔The spheroidal population What type of galaxy can result from collisions between galaxies? - ✔✔Elliptical or irregular What is a starburst galaxy? - ✔✔A galaxy with a very high rate of star formation In what part of the spectrum are starburst galaxies brightest? - ✔✔Infrared What parameters do Hubble's law relate to each other? - ✔✔Galaxy recession velocity and distance What technique for measuring distance can you use to discover Hubble's law? - ✔✔Cepheid variables in galaxies and white dwarf supernovae in galaxies How do you measure the speed of a galaxy relative to you? - ✔✔Doppler shifts What is Hubble's law? - ✔✔The faster a galaxy is moving, the farther away it is Where is the center of the Universe? - ✔✔There is no center to the Universe. Expansion is happening everywhere. How have astronomers interpreted the unexpectedly fast rotation of galaxies? - ✔✔There must be a lot of dark matter whose gravity can be felt but not seen Which of the following is not true about dark matter? - ✔✔Dark matter and dark energy are two aspects of the same phenomenon Why do we think there is a lot of dark matter in clusters of galaxies? - ✔✔Individual galaxies are moving so fast that they could not be held together by the gravity of visible matter Gravitational lensing lets us measure mass even when we can't see it How do we know that the universe's expansion is speeding up? - ✔✔We look at objects from different times in the past to see how expansion changes with time How could the universe be accelerating, despite the gravitational pull of all the matter in it? - ✔✔There could be a new force or property of space that affects the universe on its largest scales Which force is responsible for holding the nucleus together via gluons? - ✔✔strong How many types of fundamental particles exist? - ✔✔30 How many types of quarks are there, and how many types of antiquarks? - ✔✔6 quarks and 6 antiquarks What kind of particle carries the forces? - ✔✔Boson Which has the events in the right order, from early to late? - ✔✔Quark soup, protons form, nucleosynthesis, atoms form, star formation What happens because of the formation of atoms? - ✔✔The cosmic microwave background is produced What forms in nucleosynthesis? - ✔✔Most of the Helium-4 in the Universe What is a quasar? - ✔✔A very luminous source due to a black hole at the center of a galaxy that is quickly growing How did the conditions differ from the present era when the Universe was young? - ✔✔The Universe was hotter, more dense, and smoother