HW 6 - Entering the Universe

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1210

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Astronomy

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Oct 30, 2023

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Tyler Opila Homework 6 Due: 10/9 11:59 pm Reading Chapters 14, 21.4-21.6, 30 Questions 1. (14.5) Describe the solar nebula, and outline the sequence of events within the nebula that gave rise to the planetesimals. The solar nebula used to be a cloud of gas and dust. It started rortating because the angular momentum by the gravitational attraction. The nebula became a star at it’s central. The other parts became flat, creating a disk that rotates. On the outside the discs were cool, while on the inside they stayed hot. Small portions of materials only could survive farther away. Materials cooled down on the inside and made rock and metal materials. They grew in size from gravitational impacts and mergers. Outside farther away, icy pieces had the ability to grow. The big pieces formed planetesimals. 2. (14.7) How do the planets discovered so far around other stars differ from those in our own solar system? List at least two ways. There are also super-Earths and mini-Neptunes, planets intermediate in size between the terrestrial and jovian planets in our solar system and a number of exoplanets have eccentric orbits, unlike the planets of the solar system. Larger planets orbit closer to their stars, contradicting how we see the planetary system formation. There are intermediate planets in size in between terrestrial and jovian planets, such as super Earths or mini Neptunces. Some exoplanets have eccentric orbits, which are different from our solar system. 3. (14.19) Present theory suggests that giant planets cannot form without condensation of water ice, which becomes vapor at the high temperatures close to a star. So how can we explain the presence of jovian-sized exoplanets closer to their star than Mercury is to our Sun? 4. (30.9) What is a habitable zone? The habitable zone is the distance between where liquid water might pool at a star on the surface on an orbiting planet. Problems

5. (21.22) When astronomers found the first giant planets with orbits of only a few days, they did not know whether those planets were gaseous and liquid like Jupiter or rocky like Mercury. The observations of HD 209458 settled this question because observations of the transit of the star by this planet made it possible to determine the radius of the planet. Use the data given in the text to estimate the density of this planet, and then use that information to explain why it must be a gas giant. The density of the planet is 377 kg/m3. 6. (21.25) Calculate the transit depth for an M dwarf star that is 0.3 times the radius of the Sun with a gas giant planet the size of Jupiter The transit for the M dwarf star is 0.11

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