Spring Semester Review Flashcards

Vocabulary flashcards for the Spring Semester Review.

Trigonometric Parallax

A method used to determine the distance to nearby stars.

Star color

A strong indicator of a star's surface temperature.

Luminosity (of a star)

The total amount of energy a star emits into space per unit time.

Absolute Magnitude

A measure of how bright a star would be if seen from a standard distance.

Apparent Magnitude

The brightness of a star as seen from Earth.

Absorption Lines in a Star's Spectrum

Reveal the composition, temperature, and density of gases in the star's atmosphere.

Doppler Effect (in stars)

Indicates if a star is moving toward or away from us by analyzing shifts in spectral lines.

Spectral Types (hottest to coolest)

O, B, A, F, G, K, M

Dim Star (from Earth)

May be less luminous, very far away, or have light blocked by celestial matter.

Blue Stars

Considered hotter than red stars because they emit shorter wavelengths of light.

Astronomical Tool

Optical telescopes are primarily used to study stars.

Binary Stars

Systems of two stars gravitationally bound, orbiting a common center of mass.

Visual Binaries

Observed directly as two separate stars through a telescope.

Spectroscopic Binaries

Identified through shifts in spectral lines due to the Doppler effect.

Eclipsing Binaries

Provide information about star sizes through analysis of light curves.

Stellar Masses

Binary stars are important for measuring stellar masses using Kepler's laws.

Eclipsing Binary

A binary star system where one star passes in front of the other, causing brightness variations.

Mass of Stars (in binary systems)

Calculated by analyzing orbital period and distance between stars using Kepler's third law.

Motion of Binary Stars

Can determine mass, orbital characteristics, and distance from Earth.

Spectroscopic Binary

Identified by shifts in spectral lines due to the Doppler effect.

Brightness Changes (in binary systems)

Eclipsing binaries show brightness changes over time as one star eclipses the other.

Stellar Evolution

Binary systems are crucial for understanding stellar evolution through mass transfer processes and interactions.

H-R Diagram

Plots stars by luminosity (or absolute magnitude) against temperature (or spectral class).

Main Sequence (on H-R diagram)

Most stars lie here, fusing hydrogen into helium in their cores.

Top Right of H-R Diagram

Contains red giants and supergiants, large, cool, luminous stars.

White Dwarfs (on H-R diagram)

Found in the lower-left corner, characterized by high temperature but low luminosity.

Star's Position on H-R Diagram

Indicates temperature, luminosity, and evolutionary stage.

Main Sequence Lifetime

Determined by a star's mass; more massive stars have shorter lifetimes.

Main Energy Source (main sequence stars)

Nuclear fusion of hydrogen into helium in their cores.

"Turnoff Point" (on H-R diagram)

Location where stars leave the main sequence to evolve into red giants; indicates star cluster age.

Star's Radius (and H-R diagram)

More luminous stars tend to be larger and found in the upper regions of the diagram.

Giants (luminosity)

More luminous than smaller stars due to their larger surface area, despite being cooler.

Star Formation (from nebula)

Triggered by disturbances that cause gravitational collapse within the nebula.

Protostar

An early stage in star formation, where dense regions of dust and gas collapse under gravity.

Sun's Energy Generation

Through nuclear fusion in its core, converting hydrogen into helium.

Low-Mass Star (end of hydrogen)

Collapses, heats up, ignites helium fusion, expands into a red giant, then forms a white dwarf.

Red Giant

Expands and cools after exhausting hydrogen in its core, with a reddish appearance.

Carbon Creation (in stars)

Through the triple-alpha process, combining three helium nuclei.

Low-Mass Star Fate

Exhausts hydrogen, becomes a red giant, sheds outer layers (planetary nebula), forms a white dwarf.

High-Mass Star Fate

Ends in a supernova explosion, potentially forming a neutron star or black hole.

Supernova

Powerful explosion marking the end of a high-mass star's life.

High-Mass Star Lifespan

Shorter due to rapid burning of nuclear fuel.

White Dwarf

Remnant core of a low to intermediate-mass star; primarily composed of carbon and oxygen.

White Dwarf Support

Supported against gravity by electron degeneracy pressure.

Nova

A white dwarf accumulates material from a companion star, causing a bright eruption.

Chandrasekhar Limit

Maximum mass (1.4 solar masses) a white dwarf can have before collapsing.

Neutron Star

Remnant of a massive star after a supernova, composed mainly of neutrons.

Pulsar

A neutron star that emits beams of radiation from its magnetic poles, appearing to pulse.

Neutron Star Formation

From the core collapse of a massive star during a supernova.

X-Ray Bursters

Binary star systems with a neutron star that accretes material, causing X-ray bursts.

Synchrotron Radiation

Electromagnetic radiation emitted by accelerated charged particles in magnetic fields.

Black Hole

Region in space with gravitational pull so strong that nothing, not even light, can escape.

Galaxy Types

Spiral, elliptical, and irregular galaxies.

Milky Way Classification

Barred spiral galaxy.

Barred Spiral Galaxy

Spiral galaxy with a central bar-shaped structure of stars.

Irregular Galaxies

Galaxies without a defined shape, rich in gas and dust.

Edwin Hubble

Classified galaxies based on shapes using photographic plates and telescopes.

Hubble's Law

The farther a galaxy is, the faster it is receding from us.

Redshift (galaxy's light)

Suggests the galaxy is moving away from us, supporting the expanding universe.

Galactic Cannibalism

Larger galaxy accretes material from a smaller galaxy.

Standard Candles

Astronomical objects with known luminosity used to measure distances.

The Local Group

Collection of galaxies including the Milky Way and Andromeda.

Cosmology

Study of the origin, evolution, structure, and fate of the universe.

Big Bang Theory Support

Observed expansion of the universe, cosmic microwave background radiation, and abundance of light elements.

Cosmic Microwave Background (CMB)

Thermal radiation left over from recombination in the early universe.

Dark Energy

Mysterious force causing accelerated expansion of the universe.

Shape of the Universe

May be flat, based on current evidence.

Olbers' Paradox

Questions why the night sky is dark; resolved by finite age, expansion, and cosmic dust.

Observable Universe

Portion of the universe we can observe, limited by the speed of light.

Cosmological Principle

Universe is homogeneous and isotropic on large scales.

Expanding Universe (galaxies)

Galaxies move away from each other over time.

Inflation (cosmology)

Rapid expansion of the universe after the Big Bang.

Cosmic Horizon

Maximum distance from which light has reached us since the beginning of the universe.

Galaxies and Expanding Space

Galaxies move apart because space itself is expanding.

CMB Formation

Formed during recombination when the universe cooled enough for neutral hydrogen to form.

"Flat" Universe

Universe with zero curvature, balanced density, and parallel lines remaining parallel.

Recombination Era

Transition to a transparent universe, allowing emission of the CMB radiation.

Dark Matter (galaxy formation)

Provides the gravitational scaffolding for galaxy formation.

Nucleosynthesis

Creation of atomic nuclei from nucleons, occurring in stars and supernovae.

Iron (fusion in stars)

Last element formed by fusion in stars because fusing it requires more energy than released.

Massive Star Core (after iron)

Fusion ceases, the core collapses, leading to a supernova.

Supernova Types

Type I (white dwarf collapse) and Type II (massive star collapse).

Type I Supernova

Caused by the thermonuclear explosion of a white dwarf.

Type II Supernova

Occurs when a massive star's core collapses under gravity.

Nova vs. Supernova

Nova is a smaller explosion on a white dwarf; supernova is a massive explosion marking a star's death.

Supernova Explosion

Core collapses, ejecting outer layers and synthesizing elements.

Supernova Contribution

Disperses heavy elements and triggers new star formation.

Elements Heavier Than Iron

Formed through neutron capture in supernovae and neutron star mergers.

Star Clusters

Help test stellar evolution theories because they contain stars formed at the same time.

Turnoff Point (H-R diagram)

Indicates the age of a star cluster.

Planetary Nebulae

Shells of gas and dust ejected from medium-sized stars.

White Dwarf to Black Dwarf

A white dwarf cools into a black dwarf over billions of years as it radiates away its remaining thermal energy.

White Dwarf Exceeding Chandrasekhar Limit

Leads to a Type Ia supernova explosion.

Gravitational Redshifts

Light emitted from a source in a strong gravitational field loses energy and redshifts.

Pulsars

Rotating neutron stars that emit beams of radiation.

Pulsar Radiation Emission

Due to rapid rotation and strong magnetic field.

Millisecond Pulsar

Pulsar with an exceptionally rapid rotation period.

Neutron Star Glitch

Sudden change in a neutron star's rotational frequency.

Gravitational Waves

Ripples in spacetime caused by accelerating massive objects.

Producing Gravitational Waves

Requires accelerating massive objects, such as merging black holes.