Exam 17: Evolution of High-Mass Stars

Using the formula g = GM_NS/R²_NS,calculate the acceleration of gravity on a neutron star of mass 3 solar masses and radius 10 km,and express this in terms of the acceleration of gravity on the surface of the Earth (g = 9.8 m/s²).

A main-sequence star of 25 solar masses has about 12.5 times the luminosity of a 10 solar mass star.This is because:

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

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 L = 335 L_⨀ × (P/1 day),then what is this Cepheid's luminosity and absolute magnitude? Recall that the Sun's absolute magnitude is M = 5.If the apparent magnitude of the Cepheid is 25,what is this galaxy's distance in Mpc?

What is the minimum mass main-sequence star that becomes a Type II supernova?

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

Neutron stars have masses that range from:

When the core of a massive star collapses,a neutron star forms because:

Massive stars synthesize chemical elements going from helium up to iron:

The Crab Nebula is an important test of our ideas about supernova explosions because:

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

In the CNO cycle,carbon is used a catalyst for the fusion of hydrogen to helium.This means that:

Neutron stars are sometimes found in binary systems,where matter overflowing from a companion star and accreting onto the neutron star will produce X-rays and other energetic phenomena.

Where did all heavy elements in the Sun come from?

What characteristic of a star cluster is used to determine its age?

Cepheid variable stars are important because we can use them to determine the distance to any stellar group that contains some of these stars.

Why are star clusters helpful for testing our ideas of stellar structure and evolution?

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

When the first pulsar was discovered,scientists thought it might be a signal from a distant extraterrestrial civilization.However,this idea was quickly discarded because:

The production of large numbers of neutrons in nuclear reactions at the core of a massive star helps rob the core of energy and speeds its eventual collapse.