What are the measured densities of the exoplanets called "hot Jupiters," and why are these densities inconsistent with theoretical models?
What will be an ideal response?
The densities of hot Jupiters are very low, from 200 to 1500 kg/m3. This is far too low for these planets to be rocky, and, at the low end, inconsistent even with a composition of pure hydrogen and helium. Theoretical models of planetary system formation lead us to expect that light elements such as hydrogen and helium should have been expelled from the inner system; as these hot Jupiters orbit very close to their parent stars their composition is difficult to explain.
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A) collection of a few hundred million to a trillion or more stars, bound together by gravity. B) large, glowing ball of gas powered by nuclear energy. C) nearby object orbiting a planet. D) relatively small, icy object orbiting a star.
Which of the following instruments is used in the field of high energy physics to accelerate protons to very high energies along circular paths?
a) magnetron b) synchrotron c) ignitron d) betatron e) quartertron
A thin film of magnesium fluoride (n = 1.38) is applied to glass (n = 1.50) at a thickness of 100 nm. For what visible wavelength will this coating act as nonreflecting?
A. 600 nm B. 578 nm C. 552 nm D. 504 nm E. 491 nm
Consider a large truck and a small car driving up a straight, steep hill. The truck is moving at 60 miles per hour and the car at 30 miles per hour. Assuming that the speeds are constant, which of the two vehicles experiences a larger net force?
A. the truck B. the same: zero net force C. the car