ASTR Week 10 Flashcards

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Questions and Answers

What are neutron stars and pulsars associated with?

The end of a star's life cycle in a supernova

The formation of new stars

The collapse and supernova explosion of massive stars (correct)

The merging of binary stars

Black holes prevent anything inside the event horizon from escaping.

True

What causes the X-ray radiation observed in a binary system with a black hole and a blue supergiant star?

Accretion disk of material falling into the black hole

Sort the following stars according to whether they could or could not collapse into black holes:

Eta Carinae = Could collapse into a black hole XI Persei = Could collapse into a black hole The Sun = Could not collapse into a black hole Betelgeuse = Could not collapse into a black hole Sirius A = Could not collapse into a black hole Spica A = Could not collapse into a black hole Signup and view all the answers

If a star of a given mass decreases in radius, its escape speed will _____.

increase Signup and view all the answers

What are the main parts of a black hole?

Schwarzschild radius, singularity, event horizon Signup and view all the answers

How do black holes affect spacetime, matter, and radiation?

Curvature of spacetime prevents detection of matter and radiation within the event horizon, which significantly alters their motion. Signup and view all the answers

A neutron star has a radius about the size of the Earth's.

False Signup and view all the answers

Observable pulsars are found at the centers of all supernova remnants.

False Signup and view all the answers

What have astronomers detected in the center of the Crab Nebula?

Neutron star Signup and view all the answers

Why aren't all young neutron stars seen as pulsars?

Only some neutron stars are oriented to have their beams sweep in the direction of Earth. Signup and view all the answers

What process produces the rapid spin rate of millisecond pulsars?

Gas spiraling in from a nearby companion transfers angular momentum to the pulsar. Signup and view all the answers

Why is the existence of planets around a millisecond pulsar surprising?

The supernova explosion that formed the pulsar would have blown away any original planets. Signup and view all the answers

Which factors are important for explaining how a pulsar generates the detected radiation?

Squeezed magnetic field lines Signup and view all the answers

Match the following stellar end states to their characteristics:

White Dwarf = Has mass no greater than 1.4 MSun Neutron Star = Sometimes appears as a pulsar Black Hole = Time stops at its event horizon Signup and view all the answers

X-ray bursters are caused by a process similar to what?

Gas accumulation and sudden fusion reactions Signup and view all the answers

Study Notes

Neutron Stars and Pulsars

Formed from the collapse and supernova explosion of massive stars.
Neutron stars can emit pulsed radiation if aligned correctly with Earth.

Black Holes

Characterized by their event horizon, beyond which nothing can escape.
Formation occurs in binary systems, often drawing material from a companion star, forming an accretion disk.

Stellar-Sized Black Holes

Formed from stars that exceed certain mass thresholds after supernova events.
Only massive stars like Eta Carinae and XI Persei (≥ 40 solar masses) can collapse into black holes.
Stars like the Sun and Betelgeuse (≤ 18 solar masses) cannot form black holes.

Escape Speed

Escape speed from a celestial body increases as its radius decreases while maintaining mass.

Structure of Black Holes

Key components include:
- Schwarzschild Radius: The boundary around a black hole.
- Singularity: The core point of infinite density.
- Event Horizon: The outer limit where escape is impossible.

Einstein's General Theory of Relativity

Matter bends spacetime, affecting the motion of nearby matter and radiation.
Inside a black hole’s event horizon, detection of matter and radiation becomes impossible.
Spacetime curvature near black holes can alter the direction of incoming matter and radiation dramatically.

Neutron Stars

Generally possess a radius comparable to that of Earth.
Not all neutron stars become observable pulsars due to their alignment relative to Earth.

Pulsars

Observable pulsars often exist at the centers of supernova remnants, but Type II supernovae can still occur without leaving behind rotating neutron stars.
Young neutron stars need to be favorably oriented for Earth to detect their radiation beams.

Millisecond Pulsars

Rapidly spinning due to angular momentum transfer from gas pulled from companion stars.
The presence of planets around millisecond pulsars is surprising due to the destructive force of their supernova formation.

Characteristics of Neutron Stars and Pulsars

Intense magnetic fields occur due to squeezed magnetic field lines.
Neutron stars can rotate very quickly, further contributing to their pulsar characteristics.

Stellar Death Consequences

White Dwarf: Ends up in binaries and may explode as a supernova; maximum mass about 1.4 solar masses; supported by electron degeneracy pressure.
Neutron Star: Features a strong magnetic field and may appear as a pulsar.
Black Hole: Time appears to stop at the event horizon, is defined by its Schwarzschild radius.

X-Ray Bursters

Caused by a process similar to the accretion phenomena observed in neutron stars and black holes.

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Description

Test your knowledge of neutron stars, pulsars, and black holes with these flashcards for ASTR Week 10. This quiz covers key concepts such as supernova explosions and the nature of black holes in binary systems. Perfect for students looking to solidify their understanding of stellar phenomena.