Exam 17: Live Fast,die Younghigh-Mass Stellar Evolution

With the Hubble Space Telescope,you discover a Cepheid variable star in a nearby galaxy that has a period of 30 days.If nearby Cepheids follow a period-luminosity relationship that says the luminosity of the star is ,then what is this Cepheid's luminosity and absolute magnitude? Recall that the Sun's absolute magnitude is .If the apparent magnitude of the Cepheid is 25,what is this galaxy's distance in Mpc?

While traveling the galaxy in a spacecraft,you and a colleague set out to investigate the black hole at the center of our galaxy.Your colleague hops aboard an escape pod and drops into a circular orbit around the black hole,maintaining a distance of 1 AU,while you remain much farther away in the spacecraft.After doing some experiments to measure the strength of gravity,your colleague signals his/her results back to you using a green laser.What would you see?

Light is increasingly redshifted near a black hole because

The event horizon of a black hole is defined as

An iron core cannot support a massive main-sequence star because

High-mass stars differ from low-mass stars in that they burn helium to carbon when on the main sequence.

Galileo supposedly experimented with gravity by dropping two objects of different masses from the leaning tower of Pisa at the same instant and observing that they hit the ground at the same time.If Albert Einstein had done the experiment,how would his conclusion have differed from Galileo's?

Which of the following is NOT a common characteristic of a neutron star?

You observed three different star clusters and found that the main-sequence turnoff stars in Cluster 1 had spectral type A,the main-sequence turnoff stars in Cluster 2 had spectral type B,and the main-sequence turnoff stars in Cluster 3 had spectral type G.Which star cluster is the youngest?

As a high-mass main-sequence star evolves off the main sequence,it follows a __________ on the H-R diagram.

Using the Hubble Space Telescope,you discover a Cepheid variable star in a nearby galaxy that has a period of 10 days and an apparent magnitude of 20.If nearby Cepheids follow a period-luminosity relationship that says the luminosity of the star is then what is this Cepheid's absolute magnitude and distance? Note that the Sun's absolute magnitude is 5.

The Type II supernova that created the Crab Nebula was seen by Chinese and Arab astronomers in the year A.D.1054.Because the star is 6,500 light-years away from us,we know the star exploded in the year

Photons have no mass,and Einstein's theory of general relativity says

Why do large,high-mass main-sequence stars never become red giants?

Suppose you measured H-R diagrams for the two star clusters pictured below.Which of the following statements is TRUE?

Every pulsar is a neutron star,but not every neutron star is a pulsar.

Explain why a blue star cluster is likely younger than a red star cluster.

Why does the luminosity of a high-mass star remain nearly constant as the star burns heavy elements in its core,even though it is producing millions of times more energy per second than it did on the main sequence?

If the Earth were to be condensed down in size until it became a black hole,its Schwarzschild radius would be

The main difference between Cepheid variable stars and RR Lyrae stars is