Exam 11: The Lives of the Stars From Birth Through Middle Age

At what temperature do nuclear reactions begin in the core of a pre-main-sequence star?

What characteristic of Cepheid variables makes them extremely useful to astronomers?

If you were able to return to Earth 1 million years into the future,which view of the sky would be MOST likely?

The Orion Nebula is a:

After the helium flash in a low-mass star:

What happens to a star after the start of helium nuclear reactions in its core compared with what it was like before these reactions began?

Which statement about the capability of an O-type star to trigger the formation of other stars is NOT correct?

In comparing a young red giant star with the main-sequence star from which it evolved,which statement is NOT true?

Where are emission nebulae (H II regions)found?

Which stars are metal-rich?

On a Hertzsprung-Russell diagram describing the stars in a young cluster,in which position would you expect to find the T Tauri stars?

A protostar of about 1 solar mass is gradually contracting and becoming hotter.This activity causes its position in the Hertzsprung-Russell diagram to shift slowly:

Infrared stars in the Orion Nebula are examples of which stage of stellar evolution?

The star zeta Pegasi (in the constellation Pegasus,the Flying Horse)has a spectral luminosity class of B8 V,which gives it a surface temperature of about 11,000 K.According to Table 11-2 of Comins,Discovering the Essential Universe,6th ed.,the expected main-sequence lifetime of zeta Pegasi is:

The spectrum of stars in an open cluster is found to contain spectral lines from many heavy elements; the stars are known as "metal-rich." What is the source of these heavy elements?

What major physical process is taking place inside stars that are on the main sequence in the Hertzsprung-Russell diagram?

An astronomer plots the H-R diagram of a star cluster and finds that it contains hot B-type stars on the main sequence and cooler G- and K-type stars noticeably above the main sequence.This cluster is:

At what stage of evolution are the stars with similar luminosities between 50 and 100 times that of the Sun but spread over a range of temperatures?

When the Sun entered the main sequence,its core was approximately 75% hydrogen and 25% helium,by mass.What was the ratio of hydrogen nuclei to helium nuclei?

A degenerate-electron gas,which occurs in the core of a red giant star,lacks the "safety valve" of a normal gas because a rise in: