Astronomy homework 7
Vocabulary in Context: Extrasolar Planet Hunting: Match the phrases in the left-hand column to the appropriate blank in the sentences in the right-hand column. Use each phrase only once.
1. The astrometric methodwas used to find a Jupiter-sized planet through careful measurements of the changing position of a star in the sky. 2. Discovering planets through the Doppler methodrequires obtaining and studying many spectra of the same star. 3. The Kepler missionsuccessfully discovered thousands of extrasolar planets with a spacecraft that searched for transits among some 100,000 stars. 4. The transit method is used to find extrasolar planets by carefully monitoring changes in a star's brightness with time. 5. Compared to the planets of our solar system, the composition of a water world most resembles the compositions of Uranus and Neptune. 6. Observations indicating that other planetary systems often have jovian planets orbiting close to their stars are best explained by what we call migration. 7. An extrasolar planet that is rocky and larger than Earth is often called a super-Earth.
Chapter 13 Question 57: What do astronomers mean by a "selection effect". Explain why the detection of giant planets in close orbits does not necessarily mean our Solar System is unusual.
A selection effect is a bias in a detection technique. It is specific to a certain class of objects and they are selected. The giants planets tend to be found because of the gravity detection. The planets search for similar orbits, mass, and size in the Solar System.
Key Concept: Detecting Extrasolar Planets with the Transit Method: Part F As you know from Part D, most planets are undetectable by the transit method. Nevertheless, scientists have put great effort and expense into observing programs that rely on the transit method, including the Kepler mission, the TESS mission, and the CHEOPS mission. In one to two paragraphs, briefly explain why the transit method is considered so valuable despite its limitations.
The Doppler method helps us understand only a planet's minimum mass, but this is the correct mass for the planets right on the edge of Earth's orbital view. Which is the case for any planet for which can be observed. We know the radius from the transit method, and can combine the mass and radius to get a density.
