Astronomy: Star Classification and H-R Diagram

<p>Shift the wavelength of spectral lines (A)</p> Signup and view all the answers

<p>B5 (C)</p> Signup and view all the answers

<p>They encounter a shock wave (C)</p> Signup and view all the answers

<p>The pitch gets higher (B)</p> Signup and view all the answers

<p>Locations of stars in stable hydrogen fusion (D)</p> Signup and view all the answers

<p>Nuclear fusion (B)</p> Signup and view all the answers

<p>They cannot heat their centers hot enough (B)</p> Signup and view all the answers

<p>The expelled outer envelope of a medium mass star (D)</p> Signup and view all the answers

<p>White dwarfs must contain more than 1.4 solar masses (C)</p> Signup and view all the answers

<p>Not replaced (D)</p> Signup and view all the answers

<p>Exceeding the Chandrasekhar limit (A)</p> Signup and view all the answers

<p>A white dwarf in a close binary system (C)</p> Signup and view all the answers

<p>An accretion disk will form around the white dwarf (D)</p> Signup and view all the answers

<p>The material becomes hot enough that it radiates primarily at x-ray wavelengths. (A)</p> Signup and view all the answers

<p>The material will increase in mass. (B)</p> Signup and view all the answers

<p>A massive body of infinitely small size. (D)</p> Signup and view all the answers

<p>At the center of the event horizon. (D)</p> Signup and view all the answers

<p>Larger than the speed of light. (D)</p> Signup and view all the answers

<p>It will produce a type-II supernova. (D)</p> Signup and view all the answers

<p>Iron fusion releases energy rather than consuming it. (A)</p> Signup and view all the answers

<p>Hydrogen to helium. (D)</p> Signup and view all the answers

<p>It becomes a white dwarf. (A)</p> Signup and view all the answers

<p>Supernovae. (B)</p> Signup and view all the answers

<p>A shell of gas. (C)</p> Signup and view all the answers

<p>That of an atomic nucleus. (B)</p> Signup and view all the answers

<p>They become white dwarfs. (C)</p> Signup and view all the answers

<p>Location 4 (A)</p> Signup and view all the answers

<p>Shock waves from supernovae (B)</p> Signup and view all the answers

<p>To overcome the Coulomb barrier (A)</p> Signup and view all the answers

<p>The CNO cycle (C)</p> Signup and view all the answers

<p>$10^7$ K (B)</p> Signup and view all the answers

<p>Combines four hydrogen nuclei to form one helium nucleus (B)</p> Signup and view all the answers

<p>Undergoing thermonuclear fusion using the CNO cycle (C)</p> Signup and view all the answers

<p>The production of energy (B)</p> Signup and view all the answers

<p>They conserved angular momentum when they collapsed. (A)</p> Signup and view all the answers

<p>They have small surface areas. (A)</p> Signup and view all the answers

<p>Degenerate electrons. (C)</p> Signup and view all the answers

<p>A neutron star is denser than a pulsar. (A)</p> Signup and view all the answers

<p>It must rotate on an axis that differs from its magnetic field's axis. (B), It must possess a strong magnetic field. (C)</p> Signup and view all the answers

<p>It has a radius equal to the Schwarzschild radius. (A)</p> Signup and view all the answers

<p>Very little matter would be falling into it. (A)</p> Signup and view all the answers

<p>Finding x-ray binaries with massive compact companions. (A)</p> Signup and view all the answers

The change in pitch (frequency) of a sound as the source of the sound moves relative to the listener.

Stars are categorized by their spectral type, which is fundamentally related to their visible surface temperature.

The O type stars exhibit the highest visible surface temperature.

M type stars have the lowest visible surface temperature.

The color of a star is an indication of its surface temperature. Blue stars are hotter than yellow or red stars.

The change in wavelength of spectral lines emitted by an object moving relative to an observer.

A star's spectral type (like B5) directly correlates to its surface temperature. A higher spectral class letter means a hotter star.

Interstellar gas clouds can collapse and form stars when triggered by a shockwave.

A type of young star, with luminosity and temperature similar to location 4 on the HR diagram.

The process where a molecular cloud collapses under its own gravity, often triggered by external forces like shockwaves or nearby stars

A series of nuclear reactions in which hydrogen nuclei fuse to form helium, releasing energy. It's the primary energy source in stars like our Sun.

The electrostatic repulsion that protons need to overcome in order to fuse.

A series of thermonuclear reactions in which hydrogen is converted into helium in massive stars, using carbon, nitrogen, and oxygen as catalysts.

10^7 Kelvin (10 million degrees).

The process of energy transfer in the sun's outer layers, where hot material rises and cool material sinks.

The balance between the inward gravitational force and the outward pressure from nuclear fusion in the sun's core.

Nuclear fusion; converting hydrogen into helium.

Gravitational potential energy; the collapse of matter.

Low-mass stars cannot become giants because they cannot heat their centers hot enough in the process of fusion to reach the critical point.

The expelled outer layers of a medium-mass star in its death stages.

The maximum mass of a white dwarf star before it becomes unstable.

1.4 solar masses.

A white dwarf exceeding the Chandrasekhar limit.

A powerful stellar explosion that occurs when a massive star (8-50 times the mass of our Sun) exhausts its nuclear fuel and collapses under its own gravity.

A dense, hot remnant of a star's core after it has shed its outer layers and exhausted its nuclear fuel.

Stars cannot fuse iron, as iron is the most tightly bound of all nuclei.

Stars in this mass range fuse hydrogen and helium, but never reach the temperatures required to fuse carbon.

Hydrogen fusion into helium is the final nuclear reaction in a star like our Sun.

Isolated white dwarfs do not generate energy.

Supernovae are the primary sites for producing elements heavier than iron.

When material falls onto a neutron star or black hole, it heats up tremendously due to friction and gravity. This extremely hot material emits most of its energy at X-ray wavelengths, making it a prominent source of X-rays.

As material approaches a black hole, the intense gravitational pull slows down time relative to a distant observer. This effect, known as time dilation, makes the material appear to move slower and experience a longer duration of time near the black hole.

A black hole is not a physical object with a defined surface. Instead, it's a region of spacetime where gravity is so strong that nothing, not even light, can escape. The point of infinite density at the center is called the singularity.

The event horizon is the boundary around a black hole where the escape velocity is equal to the speed of light. This means that anything, including light, that crosses the event horizon is trapped forever.

The singularity lies at the center of a black hole, marking the point of infinite density and spacetime curvature. It's a point where the laws of physics as we know them break down.

Neutron stars spin rapidly due to conservation of angular momentum during their formation from collapsing stars.

Despite being very hot, neutron stars are hard to find because they have small surface areas and emit primarily in forms of radiation other than visible light.

At incredibly high densities and temperatures, electrons can fuse with protons, creating neutrons and neutrinos while releasing energy.

A neutron star has a higher density than a white dwarf, which has a higher density than a black hole.

A pulsar must be a rapidly rotating neutron star with a strong magnetic field oriented differently than its rotation axis.

The event horizon of a black hole marks the boundary beyond which nothing, including light, can escape its gravity. Its radius is equal to the Schwarzschild radius.

The Schwarzschild radius of a black hole is the distance from its center at which the escape velocity equals the speed of light. It is proportional to the black hole's mass.

Black holes are detected through their gravitational effects on nearby matter, like in X-ray binaries, where a black hole accretes material from a companion star.