Quarks to Cosmos Midterm 2

Stellar spectral classes

O, B, A, F, G, K, M, ordered by decreasing temperature.

Sun's spectral class

G2V.

Hydrostatic equilibrium

Gravity inward balanced by pressure outward.

Proton-proton chain

Process that powers the Sun: H → He + energy.

Chandrasekhar limit

~1.4 solar masses; maximum mass of a white dwarf.

Supernova

A catastrophic core collapse of a star.

Neutrino

Neutral, tiny mass particle, interacts only via weak force.

Mass lost by the Sun per second

~4 × 10^9 kg/s.

Triple-alpha process

3 He nuclei combine to form Carbon.

Escape velocity of neutron star

~0.3c.

Black hole

An object whose gravity is so strong that nothing, not even light, can escape from it.

LIGO

Laser Interferometer Gravitational-Wave Observatory detecting gravitational waves.

Cepheid variable

A pulsating star with a period-luminosity relationship useful for distance measurement.

Dark matter

Matter that does not emit, absorb, or scatter light.

Hubble's Law

v = H₀ d; relates the velocity of a galaxy to its distance.

Type Ia supernova

A type of supernova that occurs in binary systems.

Neutron degeneracy pressure

Pressure that supports a neutron star against collapse.

Gamma-ray burst (GRB)

A highly energetic explosion that can occur in the universe.

Nova

An explosive nuclear reaction on the surface of a white dwarf.

Solid evidence for dark matter

Rotation curves, gravitational lensing, and cluster dynamics.

Neutron star

A stellar remnant composed almost entirely of neutrons, very dense.

Electron degeneracy pressure

Pressure that prevents the collapse of a white dwarf.

What are the stellar spectral classes and what does the order mean?

O, B, A, F, G, K, M. Ordered by decreasing temperature. Originally alphabetical by spectral line strength.

What is the Sun’s spectral class?

G2V.

Where are red giants, main sequence, and white dwarfs on the HR diagram?

Red giants = upper right; Main sequence = diagonal; White dwarfs = lower left.

What determines if a star is on the main sequence?

Hydrogen fusion in the core.

How does luminosity depend on mass?

L ∝ M^3–4.

How does lifetime depend on mass?

Lifetime ∝ 1 / M^2.5.

What are the regions of the Sun?

Core, Radiative zone, Convective zone, Photosphere, Chromosphere, Corona.

What is hydrostatic equilibrium?

Gravity inward balanced by pressure outward.

What powers the Sun?

Proton-proton chain: H → He + energy. E = mc².

Other products of the pp-chain?

Neutrinos.

How many solar neutrinos reach Earth?~10^38 per second.

Mass lost by Sun per second?~4 × 10^9 kg/s.

Age of the Sun?~4.6 billion years.