Astrophysics vocabulary

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Star

Star

Spherical bodies that emit light in visible spectrum

Binary Star

group of 2 stars that are in stable orbit around each other

Constellation

group of stars/galaxies that forms a shape from Earth, but the stars/galaxies are usually ver far from each other

Galaxy

group of billions of stars bound together

Galaxy cluster

a lot of galaxies close together

Open stellar Cluster

giant cloud of gas with a lot of young stars

Globular Stellar Cluster

Spherical group of stars bound together

Nebula

large collection of interstellar gas, usually left behind from stars at the end of their life. They often turn into lots of stars

Supernova

The explosion of a massive star after the gravitational force overcomes electron degeneracy pressure

electron degeneracy pressure

the force that resists the collapse of matter under gravitational attraction, since no two electrons can occupy the same space

neutron degeneracy pressure

the force that opposes the gravitational collapse of a dense mass of neutrons, since no two neutrons can occupy the same space

Type 1A Supernova

a supernova of a white dwarf, characterized by the lack of hydrogen

Type 2 Supernova

a supernova of a massive star, characterized by having hydrogen

Luminosity

the total amount of energy emitted by a star every second, expressed in watts

Brightness

The power per unit area from a star

radio waves

a type of electromagnetic radiation with wavelengths >1m

micro waves

a type of electromagnetic radiation with wavelengths 1m-1mm

infrared waves

a type of electromagnetic radiation with wavelengths 1mm-1µm

visible waves

a type of electromagnetic radiation with wavelengths 700nm-400nm

UV waves

a type of electromagnetic radiation with wavelengths 400nm-100nm

X - rays

a type of electromagnetic radiation with wavelengths 10-0.1nm

Main Sequence

prominent band of stars in the Hertzsprung-Russell diagram, representing the stage of stellar evolution during which a star is fusing hydrogen into helium in its core

Giants

a class of stars that are larger and more luminous than main sequence stars of the same temperature, having exhausted their core hydrogen

White Dwarfs

a stellar remnant that comes after a low mass star runs out of nuclear fuel

Neutron Star

a small, incredibly dense, and highly magnetized stellar object formed by the collapse of a massive star's core, consisting primarily of neutrons and supported against gravity by neutron degeneracy pressure.

Pulsars

a type of neutron star which rotates quickly and emits beams of electromagnetic radiation that are observed as pulses at regular intervals

Black Hole

regions of spacetime where gravitational forces are so strong that nothing, not even light, can escape, and are formed by the collapse of massive stars

Chandrasekhar Limit

the theoretical maximum mass a white dwarf star can have and still remain a white dwarf, which is around 1.4 Solar masses. If it exceeds the limit, gravity overcomes elctron degeneracy pressure and becomes a neutron star

Oppenheimer Volkoff limit

the theoretical maximum mass of a stable neutron star, which is 3 times the mass of the sun, where neutron degeneracy pressure is unable to support the star against gravitational pull and turns into a black hole.

Expanding Universe

a cosmological model in which the distance between any two points in space is increasing over time, driven by the expansion of space itself. It is supported by evidence such as redshift or CMB.

Recessional velocity

the apparent velocity at which an astronomical object is moving away from an observer due to the expansion of the universe

Cosmic Microwave Background

an isotropic and homogeneous electromagnetic radiation that is the remnant heat from the big bang.

Cosmological Principle

the assumption that the universe is homogeneous and isotropic on large scales, meaning that its properties are the same in all directions and at all locations, and is the basis of many modern cosmological models.

Cosmic Scale Factor

quantity that represents the relative expansion or contraction of space over time in a cosmological model, helpful in finding the relative size of the universe through time

Critical Density

the density of the universe required for the universe to stop expanding

Isotropic

an adjective that describes that something(the universe or CMB) looks the same in all directions

Homogenous

an ajective that describes that every area of the universe is generally the same as every other area.

Red Shift

a process where the wavelengths emitted by stars or galaxies are lengthened out due to the expansion of the universe

Dark Matter

matter in space that we cannot account for with our measurement techniques, most likely the reason for the rotational velocity of a galaxy increasing instead of decreasing

Dark Energy

some property of space-time that causes the acceleration of the expansion of the universe

Jean's Criterion

The critical mass of gas for a star to form.

Nucleo Synthesis

the process by which new atomic elements are formed without fusion. The two types include S-types and R-types.

Black Body radiation

a type of radiation that consists of every wavelength possible but contains different amounts of energy at each wavelength for a particular temperature. stars are capable of doing this to a certain extent.

hydrostatic equilibrium

a state of a star where it is neither expanding nor contracting; the gravitational inwards force balances out with an outwards force, most likely radiation pressure.