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Granules
Small, convective cells on the solar surface that indicate the motion of plasma in the Sun's photosphere.
What chemical reaction powers the sun
4H → He
A cornel hole shows up best when using
x-rays
What Causes Sunspots
magnetic field inhibiting rising of hot gas
What Spectral Class is the sun
G
Proper motion
Motion of a star across the sky, perpendicular to our line of sight
If a star is 3 times further away than another star, how much dimmer is it
9 times dimmer
What is a galactic halo?
spherical distribution of stars and globular clusters centered on a nuclear bulge
What is an elliptical galaxy?
galaxy with an elliptical outline and a smooth distribution of brightness but no apparent structure
The chemical abundance of population I stars
indicates that the material they formed from had been enriched with material from supernovae
Which of the following types of galaxies contains primarily Population II, metal-poor, low-mass, long-lived stars?
elliptical galaxies
What is a star’s luminosity?
Total energy emitted by the star into all space per second, measured in watts
The star Alderamin has an apparent magnitude of 2.4 and an absolute magnitude of 1.4. From this information (assuming that the starlight has not been dimmed by interstellar clouds) we can say for sure that Alderamin is _____ away.
more than 10 pc
Ninety percent of all stars (if plotted on an H-R diagram) would fall into a region astronomers call:
the main sequence
The number of quasars in the universe was greatest
When the universe was only 20% of its current age
The mass of a black hole is always ____ of its host galaxy
1/200th
Why is it currently impossible to produce a spectrum of a galaxy
it is too faint
A Doppler shift can tell us what about a galaxy
How fast it is rotating / how massive it is
Which galaxy has little to no star formation
Elliptical Galaxies
What is changed during a galaxy collision
The orbits of stars
What can form during a galaxy collision
rings, tendrils of stars / gas, and other complex structures
Starburst
this abrupt increase in the number of stars being formed during galaxy collisions
Cosmological principle
the universe is about the same everywhere (apart from changes with time) but also that aside from small-scale local differences, the part we can see around us is representative of the whole.
The nearest moderately rich galaxy cluster
Virgo Cluster
Margret Geller
A woman who worked on mapping the galaxies
Sloan Digital Sky Survey
The largest universe mapping project to date
Voids
huge empty bubbles walled in by the great arcs of galaxies.
have typical diameters of 150 million light-years, with
clusters of galaxies concentrated along their walls.
How do astronomers determine location + amounts of dark matter
by measuring its gravitational effects on objects we can see.
Where is 90% of the mass of the galaxy
in the form of a halo of dark matter.
Rotation Curves
The observed rotation of spiral galaxies like Andromeda
usually seen in plots
suggest that the dark matter is found in a large halo surrounding the luminous parts of each galaxy
What are the two methods for measuring the amount of dark matter in galaxy clusters
gravitational lensing and X-ray emission
Hot Dark Matter
If dark matter moves fast / far compared to regular matter
Cold Dark Matter
If dark matter moved slowly compared to regular matter
Stanley Miller and Harold Urey
The creators of simulated conditions on early Earth
have been able to produce some of the fundamental building blocks of life
The two capabilities that life needs
a means of extracting energy from its environment, and a means of encoding and replicating information in order to make faithful copies of itself.
stromatolites
solid, layered rock formations
thought to be the fossils of oxygen-producing photosynthetic bacteria
almost 3.5 billion years old
What does life require
a solvent (a liquid in which chemicals can dissolve)
a “follow the water” strategy has been, and continues to be, a key driver in the exploration of planets both within and beyond our solar system.
What is biochemistry on Earth based on
carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur.
extremophile
An organism (usually a microbe)
tolerates or even thrives under conditions that most of the life around us would consider hostile
such as very high or low temperature or acidity,
thermophile
organisms that can tolerate high temperatures
psychrophiles
cold-adapted cells
changed the chemical composition of their membranes in order to cope with this problem
coldest temperature at which any microbe has been shown to reproduce is about –25 ºC.
acidophiles
The most acid-tolerant organisms
capable of living at pH values near zero
alkaliphiles
can grow at pH levels of about 13
biomarker
evidence of life on planets circling other stars
which rover discovered mudstones on Mars
Curiosity
Which rover is collecting samples of sedimentary rock in a former lakebed, to later return to Earth for laboratory analysis.
The perseverance rover
Why is Europa a candidate for life
ocean of liquid water
contact with rocky mantle
chemical mixing possibility
Why is Enceladus a candidate for life
liquid water ocean
Why is Titana candidate for life
thick atmosphere
Uv light that creates Tholins
Tholins
the Sun’s ultraviolet light breaks apart and recombines Nitrogen and Methane into more complex organic compounds
habitable zone
a region around a star where suitable conditions might exist for life
focuses on life’s requirement for liquid water
Who started the first search for radio signals that come from aliens
Frank Drake
SETI
Search for Extraterrestrial Intelligence
Who funded Breakthrough: Listen
Yuri Milner
Jill Tarter
A leading Scientist in the SETI field
technosignatures
signs of technology from other civilizations
O, B, A, F, G, K, M [L, T, Y]
Order of spectral classes of stars
Parallax
the apparent change in direction of a remote object
due to a change in vantage point of observer
What is the force that holds the nucleus together
Strong Nuclear Force
Hottest part of Sun’s atmosphere
Corona
Roche Obe
Region around star in binary system where orbiting material is gravitationally bound
Spicules
a dynamic jet of plasma in the Sun's chromosphere
When did dark energy accelerate the expansion of the universe
5 billion years after the big bang
What condition must be true for a pair of stars to be classified as an optical double
must lie in almost the same direction from earth
must not be orbiting each other
Two most abundant elements in the sun
hydrogen and heliun
Who discovered stars were made of hydrogen and helium
Cecila Payne-Gapachkin
Convective zone
Outermost layer of interior of the sun
takes energy from radiative zone to surface with convection zones
cooler energy sinks
Radiative Zone
layer of sun above core
transmits light very easily
Photosphere
the layer where sun becomes opaque
What star did Thomas Henderson measure the parallax of
Alpha Centauri
Neutrino
fundamental particle
no charge
mass tiny
rarely interact with matter
Temperature of Photosphere
5800 K
When is fusion possible?
temp > 12 million K
Speed > 1000 km / sec
Luminosity
The total amount of energy a star emits per second (all wavelengths)
Plasma
What state of matter is the sun
Helioseismology
study of sun pulsations
used to determine characteristics of interior
What star did Thomas Henderson measure the parallax of
Gl Cygni
Period Luminosity relation
The pulsation period of Cepheid Variable stars is directly related to their intrinsic luminosity
Cepheid variables
large yellow pulsating stars
several hundred in the Milky Way
periods of 3-50 days
variations in luminosity
Who discovered Cepheid variables
Henrietta Swan Leavit
Light curve
a graph that shows how the brightness of a variable star changes with time
Corona
above the chromosphere and extends millions of kilometres into outer space
51 Pegasi B
The first star where exoplanets were discovered
N
The fraction of intelligent civilizations that have the tech to communicate across the stars
Rstar
The rate new stars form per year
Fp
The fraction of stars that have planets
Fe
The fraction of systems that house a habitable planet
Fl
The fraction of habitable planets that develop life
Fi
The fraction of planets with life where intelligence evolves
Fc
The number of communicating civilizations in our galaxy
L
The average lifetime of a communicating civilization
Energy of the sun is generated
in its central core by fusion of hydrogen nuclei
A coronal hole shows up most prominently on what kind of photograph?
X-ray
A Type I supernova is believed to occur when
a white dwarf exceeds the Chandrasekhar limit.
Type II Supernova
The supernova that happens when a massive star dies
What makes a red giant star so large
The hydrogen-burning shell is heating the envelope and making it expand drastically.
When a star leaves the main sequence and expands toward the red giant region, what is happening inside the star?
Hydrogen burning is taking place in a spherical shell just outside the core; the core itself is almost pure helium.
Henrietta Leavitt
Peroid-lumonisty relasonship for cepheid variables was discovered by
The higher the lumonosity of a Cepheid varaible
the longer the period of variations
Dark energy
matter-energy needed to bridge the gap between the energy we see or infer and the energy needed to make the universe flat