Exam 5: The Formation of Stars and Planets

Which of the following is NOT a characteristic of the early Solar System,based on current observations?

If an interstellar cloud having a diameter of 10¹⁶ m and a rotation period of a million years were to collapse to form a sphere that had the diameter of our solar system,40 AU,what would its rotation period be?

How much material in an accretion disk goes into forming the planets,moons,and smaller objects?

Two competing models of the formation of giant gaseous planets suggest they form either from gas accreting onto a rocky core or from:

Conservation of energy describes why a skater spins faster when her arms are pulled in compared to when they are straight out.

The primordial atmosphere of the Earth consisted of what type of chemical elements and from where did it originate? What chemical elements did the secondary atmosphere of the Earth consist of and from where did it originate?

What prevented the Moon from maintaining any atmosphere with which it originally formed?

What is the ratio of the orbital angular momentum of Jupiter to its spin angular momentum? Jupiter's orbit has a semimajor axis of 5 AU and a period of 12 years,and Jupiter has a rotation period of 0.4 day and a radius of 70,000 km.

The maximum mass of a brown dwarf is approximately 0.08 times the mass of the Sun.

According to the conservation of angular momentum,if an ice skater starts spinning with her arms out wide,then slowly pulls them close to her body,this will cause her to:

What does conservation of angular momentum mean?

Most planets currently found around other stars are:

To date astronomers have not yet detected Earth-size planets around normal stars.

Current technology is sensitive enough to detect some extra-solar planets by a dip in brightness of the parent star as the planets pass between us and it.

Over 330 extra-solar planets have been detected by direct imaging of the planets.

Suppose you observe a star emitting a certain emission line of helium at 584.8 nm.The rest wavelength of this line is 587.6 nm.How fast is the star moving? Is it moving toward you or away from you?

What happens to the gravitational energy of gas as it falls toward and eventually hits the accretion disk surrounding a protostar?

For a star that lies in the plane of Earth's orbit around the Sun,how does the observed wavelength of the hydrogen absorption line at 656.28 nm in its spectrum change in wavelength (if at all)with the time of year?

Explain why most of the extra-solar planets astronomers have detected are so-called "hot Jupiters."