Units 6-23 Vocab Flashcards
1.4 solar masses; the theoretical maximum mass a white dwarf star can have and still remain a white dwarf
white dwarf limit
The central region of a star, in which nuclear fusion can occur.
Core
What method do we use to measure distances within the solar system?
Radar Ranging
A particularly luminous type of pulsating variable star that follows Leavitt’s law (also called the period–luminosity relation) and hence is very useful for measuring cosmic distances
Cepheid variable stars
3 different ways of measuring the amount of dark energy in clusters of galaxies?
from galaxy orbits, from the temperature of the hot gas in clusters, and from the gravitational lensing predicted by Einstein.
A cluster of up to several thousand stars; l are found only in the disks of galaxies and often contain young stars.
Open clusters
A graph plotting individual stars as points, with stellar luminosity on the vertical axis and spectral type (or surface temperature) on the horizontal axis.
An H-R diagram
A method of measuring distances within the solar system by bouncing radio waves off planets.
Radar Ranging
a particle not affected by the strong nuclear forces, but is only subjected to the weak forces; includes electrons and neutrons
Leptons
a place where gravity has crushed matter into oblivion, creating a hole in the universe from which nothing can escape, not even light.
black hole
a place where spacetime is curved so much that it essentially forms a bottomless pit, making it like a hole in spacetime.
Black Hole
a process in which subatomic particles can “tunnel” from one place to another even when they don’t actually have enough energy to overcome an energy barrier between the two places.
Quantum tunneling
A redshift caused by the fact that time runs slowly in gravitational fields.
Gravitational Redshifts
A region in which energy is transported outward by convection.
Convection Zone
a region of cosmic gas and dust formed from the cast-off outer layers of a dying star
planetary nebula
A small, spectral type M star that displays particularly strong flares on its surface.
Flares star
A spherically shaped cluster of up to a million or more stars; are found primarily in the halos of galaxies and contain only very old stars.
Globular clusters
a standard relative to which motion and rest may be measured; any set of points or objects that are at rest relative to one another enables us, in principle, to describe the relative motions of bodies.
Frame of reference
a star showing a sudden large increase in brightness and then slowly returning to its original state over a few months.
Nova
A star system that contains two stars.
Binary star system
A state of balance in which the force of gravity pulling inward is precisely counteracted by pressure pushing outward; also referred to as hydrostatic equilibrium.
gravitational equilibrium
A sudden and dramatic expansion of the universe thought to have occurred at the end of the GUT era
inflation
A supernova that occurs when an accreting white dwarf reaches the white dwarf limit, ignites runaway carbon fusion, and explodes like a bomb; often called a Type Ia supernova.
White Dwarf Supernova
A Type Ia supernova; a type of supernova that occurs in binary systems in which one of the stars is a white dwarf.
white dwarf supernova
A type of fundamental particle that has extremely low mass and responds only to the weak force; they are leptons and come in three types— electron neutrinos, muon neutrinos, and tau neutrinos.
Neutrinos
a type of pressure that can occur even in the absence of heat. It arises from the combination of the exclusion principle and the uncertainty principle. It is the dominant form of pressure in the astronomical objects known as brown dwarfs, white dwarfs, and neutron stars.
Degeneracy pressure
a type of subatomic particle; includes a photon or meson whose spin quantum number is zero or an integral number.
Bosons
a type of subatomic particle; includes protons, neutrons, and electrons; whose spin quantum number is an odd multiple of 1/2.
Fermions
a very large star of high luminosity and low surface temperature. These stars are thought to be in a late stage of evolution when no hydrogen remains in the core to fuel nuclear fusion.
Red Giant
A way of classifying a star by the lines that appear in its spectrum; it is related to surface temperature. The basic spectral types are designated by letters (OBAFGKM, with O for the hottest stars and M for the coolest) and are subdivided with numbers from 0 through 9.
Spectral Types
A white dwarf in a close binary system can acquire hydrogen from its companion through an ______________ _______.
accretion disk
a ________-mass star begins hydrogen shell fusion and then goes through a series of stages, fusing successively heavier elements as its core temperature rises.
high
After energy emerges from the radiation zone, ___________ carries it the rest of the way to the photosphere, where it is radiated into space as sunlight.
Convection
an episode in which something is hotter for a limited time, something that can occur at various stages of stellar evolution.
Thermal pulses
An object for which we have some means of knowing its true luminosity, so that we can use its apparent brightness to determine its distance with the luminosity–distance formula.
Standard Candles
an underlying background energy that exists in space throughout the entire Universe.
vacuum energy
What type of star are the exposed cores of stars that have already died, meaning they have no further means of generating energy through fusion?
White dwarfs
Blotches on the surface of the Sun that appear darker than surrounding regions.
Sunspots
Bursts of charged particles from the Sun’s corona that travel outward into space.
Coronal Mass Ejections
By grouping galaxies according to luminosity and color, What color star-forming cloud do spiral and irregular galaxies belong to?
star-forming blue cloud
By grouping galaxies according to luminosity and color, What color star forming cloud do elliptical galaxies belong to?
non-star-forming red sequence
Caused by helium fusion igniting frequently on the neutron star’s surface; ccur in low-mass X-ray binary systems where a neutron star and low-mass main sequence star are in orbit around one another.
x-ray bursts
Does mass increase at speeds close to the speed of light?
YES
electromagnetism and the weak force became distinct at the end of the era.
Electroweak era
Equation that tells us that mass itself contains an enormous amount of potential energy.
E=mc^2
Era began at 10^–38 seconds to 10-10 second after the Big Bang, when the temperature of the universe cooled enough to separate the Strong Force from the Electroweak Force (the name for the two unified forces of Electro-magnetism and the Weak Nuclear Force). This Era contains two sub-eras - Inflation and Reheating.
Electroweak Era
Era prior to 10^-43 seconds after the Big Bang, when we believe that the four basic forces of nature, 1) gravity, 2) nuclear strong force, 3) nuclear weak force, and 4) electromagnetic force were combined into a single “super” force.The temperature of the universe was 1 x 10^32 degrees Celsius.
Planck era
At very high energy and temperature, the three fundamental forces (the Strong Nuclear Force, the Weak Nuclear Force, and Electro-magnetism) of the Standard Model are merged into one single force.Era begins at 10^-43 when gravity separates from the other three unified forces, which do remain unified. It ends when Inflation begins at 10^-38 seconds.
GUT era
explains three of the four fundamental forces that govern the universe: electromagnetism, the strong force, and the weak force.
standard model
Fusion of protons and neutrons into helium ceased at the end of the era
era of nucleosynthesis
Galaxies are neither disklike nor rounded in appearance
Irregular Galaxies
Galaxies are rounder and redder than spiral galaxies and contain less cool gas and dust.
Elliptical galaxies
Galaxies began to form at the end of the era.
era of nuclei
Galaxies with prominent disks and spiral arms
Spiral Galaxies
Gravity became distinct at the start of the era
GUT era
helium will begin to fuse into carbon by a reaction known as the triple-alpha process, because it converts three helium nuclei into one carbon atom.
helium fusion
How can we measure the masses of stars in a binary star system?
Using Newton’s version of Kepler’s third law if we can measure the orbital period and separation of the two stars.
How did ancient thinkers imagine the Sun as?
to be some type of fire, perhaps a lump of burning coal or wood.
How do elliptical galaxies tend to be grouped?
large clusters
How do spiral galaxies tend to be grouped?
they reside in relatively small groups
How does gravity affect time?
Time runs more slowly in places where gravity is stronger
How many different types of leptons are there?
6
How many different types of quarks are there?
6
How were Neutron stars discovered?
Through Pulsars
Hubble’s Law equation
v= H0 x d
hydrogen fusion reactions taking place in a shell of hydrogen surrounding a core of helium or heavier elements in an ageing star
Hydrogen shell fusion
If you observe an object moving by you at high speed, how is its length and mass different than when at rest?
its length is shorter than its length when at rest, and its mass is greater than its mass when at rest.
If you observe an object moving by you at high speed, is its time running faster or more slowly than yours?
More slowly
In its final stages of life, a high-mass star’s core becomes what?
It becomes hot enough to fuse carbon and other heavy elements.
The type of geometry in which the rules of geometry for a flat plane hold, such as that the shortest distance between two points is a straight line and that the sum of the angles in a triangle is 180°.
Flat geometry
Instrument that has detected pulses of gravitational waves produced when orbiting neutron stars or black holes ultimately merge.
LIGO
Interior layers of the sun from inside, out?
core, radiation zone, convection zone, photosphere, chromosphere, and corona.
is a massive explosion of a dying star.
supernova
is a star—a giant ball of hot gas that generates light and shines it brightly in all directions.
Sun
made up of a normal star and a collapsed star (a white dwarf, neutron star, or black hole).
x-ray binary
marks the boundary between our observable universe and the inside of the black hole
Event Horizon
Mathematical expression of the idea that more distant galaxies move away from us faster: v = H0 × d, where v is a galaxy’s speed away from us, d is its distance, and H0 is Hubble’s constant.
Hubble’s Law
Matter particles annihilated all the antimatter particles by the end of the era.
Particle era
molecules formed by atoms consisting of antiprotons, antineutrons, and positrons. Stable _________ does not appear to exist in our universe.
Antimatter
name given to the form of energy thought to be causing the expansion of the universe to accelerate.
Dark energy
name given to the unseen mass whose gravity governs the observed motions of stars and gas clouds.
Dark matter
occur in distant galaxies but shine so brightly in the sky that they must be the most powerful explosions we ever observe in the universe.
Gamma-ray bursts
Once the lowest energy level is filled, the other electrons are forced into higher and higher energy states resulting in them travelling at progressively faster speeds. These fast moving electrons create a pressure which is capable of supporting a star! What is this pressure called?
electron degeneracy pressure
Predicts the ratio of protons to neutrons during the era of nucleosynthesis, and from this predicts that the chemical composition of the universe should be about 75% hydrogen and 25% helium (by mass)
Big Bang Theory
Epoch prior to 10-43 s after the Big Bang, when we believe that the four basic forces of nature, 1) gravity, 2) nuclear strong force, 3) nuclear weak force, and 4) electromagnetic force were combined into a single “super” force.
Planck Epoch
Radiation left over from the Big Bang; Its spectrum matches the characteristics expected of the radiation released at the end of the era of nuclei, confirming a key prediction of the Big Bang theory.
cosmic microwave background
A region of the interior in which energy is transported primarily by radiative diffusion.
Radiation Zone
rapidly spiraling matter that is in the process of falling into an astronomical object; which matter swirls toward the white dwarf’s surface.
accretion disk
rotating neutron stars observed to have pulses of radiation at very regular intervals that typically range from milliseconds to seconds.
pulsars
Short-lived phenomena on the Sun, including the emergence and disappearance of individual sunspots, prominences, and flares; sometimes called solar weather.
Solar activity
Stars on the ________ _________ are all fusing hydrogen into helium in their cores.
main sequence
Stars that appear just below the supergiants on the H-R diagram because they are somewhat smaller in radius and lower in luminosity.
Giants
Stars that grow alternately brighter and dimmer as their outer layers expand and contract in size.
Pulsating Variable Stars
Stars with masses above 8Msun?
high mass stars
Stars with masses less than 2Msun?
low-mass stars
Epoch started about 10-35 seconds came to an end about 10-6 second. We begin to see the rapid formation of quarks and anti-quarks. The combination of quarks and gluons make-up protons and neutrons, but during this epoch they had too much energy to be confined inside them.
Quark Epoch
Tells us that if the universe were infinite, unchanging, and everywhere the same, the entire night sky would be as bright as the surface of the Sun, and it would not be dark at night.
Olbers’ paradox
tells us that two fermions of the same type cannot occupy the same quantum state at the same time. This principle does not apply to bosons.
exclusion principle
tells us that we cannot simultaneously know the precise values of an object’s position and momentum—or, equivalently, its energy and the precise time during which it has this energy.
uncertainty principle
The amount of light reaching us per unit area from a luminous object; often measured in units of watts/m2.
Apparent Brightness
The balance between the rate at which fusion releases energy in the star’s core and the rate at which the star’s surface radiates this energy into space.
Energy balance
the ball of neutrons created by the collapse of the iron core in a massive star supernova.
neutron star
The boundary of our observable universe, which is where the lookback time is equal to the age of the universe. Beyond this boundary in spacetime, we cannot see anything at all.
Cosmological Horizon
the building blocks of protons and neutrons
Quarks
the Carbon-Nitrogen-Oxygen cycle, a process of stellar nucleosynthesis in which stars on the Main Sequence fuse hydrogen into helium via a six-stage sequence of reactions.
CNO cycle
The chain of reactions by which low-mass stars (including the Sun) fuse hydrogen into helium.
Proton-Proton chain
The core again shrinks after helium core fusion ceases. Helium shell fusion begins around the inert carbon core beneath the hydrogen- fusing shell. The outer layers expand again, making the star into a double shell–fusion star. The star’s energy generation never reaches equilibrium during this time; instead, the star experiences a series of thermal pulses and ultimately expels its outer layers into space as a planetary nebula. The remaining “dead” stellar core is a white dwarf. What is this describing?
Death of a low mass star
the core left over from a low-mass star, supported against the crush of gravity by electron degeneracy pressure.
white dwarf
The era of the universe lasting from 10-10 second to 0.001 second after the Big Bang, during which subatomic particles were continually created and destroyed, and ending when matter annihilated antimatter.
Particle Era
The era of the universe lasting from about 0.001 second to about 3 minutes after the Big Bang, by the end of which virtually all of the neutrons and about one-seventh of the protons in the universe had fused into helium.
Era of nucleosynthesis
The era of the universe lasting from about 3 minutes to about 380,000 years after the Big Bang, during which matter in the universe was fully ionized and opaque to light. The cosmic background radiation was released at the end of this era.
Era of nuclei
The era of the universe lasting from about 500,000 years to about 1 billion years after the Big Bang, during which it was cool enough for neutral atoms to form.
Era of atoms
