Astronomy Final

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109 Terms

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Granules

Small, convective cells on the solar surface that indicate the motion of plasma in the Sun's photosphere.

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What chemical reaction powers the sun

4H → He

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A cornel hole shows up best when using

x-rays

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What Causes Sunspots

magnetic field inhibiting rising of hot gas

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What Spectral Class is the sun

G

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Proper motion

Motion of a star across the sky, perpendicular to our line of sight

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If a star is 3 times further away than another star, how much dimmer is it

9 times dimmer

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What is a galactic halo?

spherical distribution of stars and globular clusters centered on a nuclear bulge

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What is an elliptical galaxy?

galaxy with an elliptical outline and a smooth distribution of brightness but no apparent structure

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The chemical abundance of population I stars

indicates that the material they formed from had been enriched with material from supernovae

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Which of the following types of galaxies contains primarily Population II, metal-poor, low-mass, long-lived stars?

elliptical galaxies

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What is a star’s luminosity?

Total energy emitted by the star into all space per second, measured in watts

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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

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Ninety percent of all stars (if plotted on an H-R diagram) would fall into a region astronomers call:

the main sequence

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The number of quasars in the universe was greatest

When the universe was only 20% of its current age

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The mass of a black hole is always ____ of its host galaxy

1/200th

17
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Why is it currently impossible to produce a spectrum of a galaxy

it is too faint

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A Doppler shift can tell us what about a galaxy

How fast it is rotating / how massive it is

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Which galaxy has little to no star formation

Elliptical Galaxies

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What is changed during a galaxy collision

The orbits of stars

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What can form during a galaxy collision

rings, tendrils of stars / gas, and other complex structures

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Starburst

this abrupt increase in the number of stars being formed during galaxy collisions

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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.

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The nearest moderately rich galaxy cluster

Virgo Cluster

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Margret Geller

A woman who worked on mapping the galaxies

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Sloan Digital Sky Survey

The largest universe mapping project to date

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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.

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How do astronomers determine location + amounts of dark matter

by measuring its gravitational effects on objects we can see.

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Where is 90% of the mass of the galaxy

in the form of a halo of dark matter.

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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

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What are the two methods for measuring the amount of dark matter in galaxy clusters

gravitational lensing and X-ray emission

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Hot Dark Matter

If dark matter moves fast / far compared to regular matter

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Cold Dark Matter

If dark matter moved slowly compared to regular matter

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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

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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.

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stromatolites

  • solid, layered rock formations

  • thought to be the fossils of oxygen-producing photosynthetic bacteria

  • almost 3.5 billion years old

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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.

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What is biochemistry on Earth based on

carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur.

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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,

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thermophile

organisms that can tolerate high temperatures

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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.

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acidophiles

  • The most acid-tolerant organisms

  • capable of living at pH values near zero

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alkaliphiles

can grow at pH levels of about 13

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biomarker

evidence of life on planets circling other stars

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which rover discovered mudstones on Mars

Curiosity

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Which rover is collecting samples of sedimentary rock in a former lakebed, to later return to Earth for laboratory analysis.

The perseverance rover

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Why is Europa a candidate for life

  • ocean of liquid water

  • contact with rocky mantle

  • chemical mixing possibility

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Why is Enceladus a candidate for life

liquid water ocean

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Why is Titana candidate for life

  • thick atmosphere

  • Uv light that creates Tholins

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Tholins

  • the Sun’s ultraviolet light breaks apart and recombines Nitrogen and Methane into more complex organic compounds

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habitable zone

  • a region around a star where suitable conditions might exist for life

  • focuses on life’s requirement for liquid water

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Who started the first search for radio signals that come from aliens

Frank Drake

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SETI

Search for Extraterrestrial Intelligence

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Who funded Breakthrough: Listen

Yuri Milner

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Jill Tarter

A leading Scientist in the SETI field

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technosignatures

signs of technology from other civilizations

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O, B, A, F, G, K, M [L, T, Y]

Order of spectral classes of stars

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Parallax

  • the apparent change in direction of a remote object

  • due to a change in vantage point of observer

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What is the force that holds the nucleus together

Strong Nuclear Force

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Hottest part of Sun’s atmosphere

Corona

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Roche Obe

Region around star in binary system where orbiting material is gravitationally bound

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Spicules

a dynamic jet of plasma in the Sun's chromosphere

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When did dark energy accelerate the expansion of the universe

5 billion years after the big bang

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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

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Two most abundant elements in the sun

hydrogen and heliun

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Who discovered stars were made of hydrogen and helium

Cecila Payne-Gapachkin

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Convective zone

  • Outermost layer of interior of the sun

  • takes energy from radiative zone to surface with convection zones

  • cooler energy sinks

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Radiative Zone

  • layer of sun above core

  • transmits light very easily

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Photosphere

the layer where sun becomes opaque

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What star did Thomas Henderson measure the parallax of

Alpha Centauri

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Neutrino

  • fundamental particle

  • no charge

  • mass tiny

  • rarely interact with matter

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Temperature of Photosphere

5800 K

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When is fusion possible?

  • temp > 12 million K

  • Speed > 1000 km / sec

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Luminosity

The total amount of energy a star emits per second (all wavelengths)

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Plasma

What state of matter is the sun

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Helioseismology

  • study of sun pulsations

  • used to determine characteristics of interior

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What star did Thomas Henderson measure the parallax of

Gl Cygni

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Period Luminosity relation

The pulsation period of Cepheid Variable stars is directly related to their intrinsic luminosity

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Cepheid variables

  • large yellow pulsating stars

  • several hundred in the Milky Way

  • periods of 3-50 days

  • variations in luminosity

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Who discovered Cepheid variables

Henrietta Swan Leavit

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Light curve

a graph that shows how the brightness of a variable star changes with time

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Corona

above the chromosphere and extends millions of kilometres into outer space

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51 Pegasi B

The first star where exoplanets were discovered

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N

The fraction of intelligent civilizations that have the tech to communicate across the stars

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Rstar

The rate new stars form per year

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Fp

The fraction of stars that have planets

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Fe

The fraction of systems that house a habitable planet

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Fl

The fraction of habitable planets that develop life

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Fi

The fraction of planets with life where intelligence evolves

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Fc

The number of communicating civilizations in our galaxy

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L

The average lifetime of a communicating civilization

92
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Energy of the sun is generated

in its central core by fusion of hydrogen nuclei

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A coronal hole shows up most prominently on what kind of photograph?

X-ray

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A Type I supernova is believed to occur when

a white dwarf exceeds the Chandrasekhar limit.

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Type II Supernova

The supernova that happens when a massive star dies

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What makes a red giant star so large

The hydrogen-burning shell is heating the envelope and making it expand drastically.

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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.

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Henrietta Leavitt

Peroid-lumonisty relasonship for cepheid variables was discovered by

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The higher the lumonosity of a Cepheid varaible

the longer the period of variations

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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