ASTRO 101 CH. 14 HMW

Sorting Task: The Bizarre Stellar Graveyard Listed following are distinguishing characteristics of different end states of stars. Match these to the appropriate consequence of stellar death.

Ranking Task: The Size of Planets, Stars, and Stellar Remnants Listed following are several astronomical objects. Rank these objects based on their diameter, from largest to smallest. (Note that the neutron star and black hole in this example have the same mass to make your comparison easier, but we generally expect black holes to have greater masses than neutron stars.) (Jupiter, the Moon, the event horizon of a two solar mass black hole, a two solar mass neutron star, main sequence star of spectral type A, a one solar mass white dwarf)

The main-sequence star is obviously much larger than a planet such as Jupiter. A one-solar-mass white dwarf is about the size of Earth, which makes it larger than the Moon.

Listed following are several astronomical objects. Rank these objects based on their mass, from largest to smallest. (Be sure to notice that the main-sequence star here has a different spectral type from the one in Part A.) (a typical neutron star, Jupiter, the Moon, a typical black hole-formed in a supernova, a one solar mass white dwarf, main sequence star of spectral type M)

Note that while the rankings shown are correct for "typical" white dwarfs, neutron stars, and black holes:

Listed following are several astronomical objects. Rank these objects based on their density, from highest to lowest. (a typical neutron star, a main sequence star, the singularity of a black hole, a one solar mass white dwarf)

The singularity of a black hole:

Neutron stars are much more dense than:

Process of Science: Identifying Stellar Corpses The following items describe observational characteristics that could indicate that an object is either a white dwarf or a neutron star. Match each characteristic to the correct object.

white dwarfs may be surrounded by:

The following items describe observational characteristics that may indicate that an object is either a neutron star or a black hole. Match each characteristic to the correct object; if the characteristic could apply to both types of object, choose the bin labeled "Both neutron stars and black holes."

radio pulses and X-ray bursts cannot come from black holes, because both are caused by events that happen on the surface of a compact object.

The Chandra X-Ray Observatory has detected X rays from a star system that contains a main-sequence star of spectral type B6. The X-ray emission is strong and fairly steady, and no sudden bursts have been observed. Which of the following statements are reasonable conclusions about this system?

The system is an X-ray binary, which means the companion to the main-sequence star can be either a neutron star or a black hole.

What is the key observation needed to determine whether the compact object in Part C is a neutron star or a black hole?

The Doppler shifts will allow you to determine the speed (or at least the component of the speed that is in your line of sight) of the main-sequence star as it orbits the compact object.

Sorting Task: Distinguishing Massive Star and White Dwarf Supernovae To distinguish between properties of the two major types of supernovae: massive star supernovae and white dwarf supernovae. All supernovae represent the explosions of stars, but current understanding suggests there are two basic types of supernovae: one that occurs when a massive star reaches the end of its life, and the other that occurs when a white dwarf star explodes because its mass has exceeded the white dwarf limit (also called the Chandrasekhar limit) of 1.4 solar masses.

Each item below describes an observation of a hypothetical supernova. Classify each observation as either "Not surprising" if it fits in with our current understanding of supernovae, or "Surprising" if the observation would cause us to rethink our understanding of supernovae.

the radius of a white dwarf is determined by a balance between the inward force of gravity and the outward push of:

a ____ occurs when hydrogen fusion ignites on the surface of a white dwarf in a binary system

a _______ occurs when fusion creates iron in the core of a star

a white dwarf in a close binary system will explode as a supernova if it gains enough mass to exceed the:

A ________ consists of hot, swirling gas captured by a white dwarf (or neutron star or black hole) from a binary companion star.

a _______ can occur only in a binary system, and all such events are thought to have the same luminosity

From the viewpoint of an observer in the orbiting rocket, what happens to time on the other rocket as it falls toward the event horizon of the black hole?

As the falling rocket plunges toward the event horizon, an observer in the orbiting rocket would see that the falling rocket __________

you know that from afar you'll never see the in-falling rocket cross the event horizon, yet it will still eventually disappear from view. Why?

If you were inside the rocket that falls toward the event horizon, you would notice your own clock to be running __________.

If you were inside the rocket that falls toward the event horizon, from your own viewpoint you would __________.

From your point of view, time runs normally in your spaceship and gravity must accelerate you as you fall toward the black hole.

Which of these objects has the smallest radius? -a 1.2Msun white dwarf -a 0.6Msun white dwarf -Jupiter

If we see a nova, we know that we are observing:

Which of these isolated neutron stars must have had a binary companion?

What would happen to a neutron star with an accretion disk orbiting in a direction opposite to the neutron star's spin

In a massive star supernova explosion, a stellar core collapses down to form a neutron star roughly 10 kilometers in radius. The gravitational potential energy released in such a collapse is approximately equal to GM2r where M is the mass of the neutron star, r is its radius, and G=6.67×10−11m3/kg×s2 is the gravitational constant. Using this formula, estimate the amount of gravitational potential energy released in a massive star supernova explosion.

In a massive star supernova explosion, a stellar core collapses down to form a neutron star roughly 10 kilometers in radius. The gravitational potential energy released in such a collapse is approximately equal to GM2r where M is the mass of the neutron star, r is its radius, and G=6.67×10−11m3/kg×s2 is the gravitational constant. How does it compare with the amount of energy released by the Sun during its entire main-sequence lifetime?

Which of these objects has the largest radius? -1.2 Msun white dwarf -1.5 Msun neutron star -3.0 Msun black hole

Viewed from a distance, how would a flashing red light appear as it fell into a black hole?

Which of these black holes exerts the weakest tidal forces on an object near its event horizon? -10Msun black hole -100Msun black hole -10^6Msun black hole

What would happen if the Sun suddenly became a black hole without changing its mass?

Which of these binary systems is most likely to contain a black hole? -an X-ray binary containing an O star and another object of equal mass - a binary with an X-ray burster - an X-ray binary containing a G star and another object of equal mass

Calculate the Schwarzschild radius (in kilometers) for each of the following. A 108MSun black hole in the center of a quasar

Calculate the Schwarzschild radius (in kilometers) for each of the following. A 5MSun black hole that formed in the supernova of a massive star.

Calculate the Schwarzschild radius (in kilometers) for each of the following. A mini-black hole with the mass of the Moon.

Calculate the Schwarzschild radius (in kilometers) for each of the following. A miniblack hole formed when a superadvanced civilization decides to punish you (unfairly) by squeezing you until you become so small that you disappear inside your own event horizon. (Assume that your mass is 50 kg.)

Where do gamma-ray bursts tend to come from?

At peak brightness, the white dwarf supernova is approximately __________ times as luminous as the massive star supernova at its peak brightness.

For the white dwarf supernova, the luminosity 175 days after it reaches peak brightness is about __________ of the luminosity at peak brightness

Approximately how many days does it take for a white dwarf supernova to decline to 10% of its peak brightness?

Approximately how many days does it take for a massive star supernova to decline to 10% of its peak brightness?

Approximately how many days does it take for a massive star supernova to decline to 1% of its peak brightness?

consider three planets. All have the same mass as Earth but with different radii. For which planet is the escape velocity from the surface the largest? Planet 1 = ___________________ Planet 2 = ______________ Planet 3 = _________

the event horizon of a 3 solar mass black hole is roughly the same size as:

the event horizon for a 10 solar mass black hole is:

which of the following is true about observational evidence for black holes?

some Xray binaries are candidates for black holes because:

if you could measure the orbital speeds of particles in an accretion disk around a black hole, you would notice that:

if jupiter turned into a black hole:

what makes us think that black holes really exist?