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Astronomy Test 2
Terms in this set (116)
(astronomy) a shift in the spectra of distant galaxies toward longer wavelengths
hot dense objects
the distance between wave crests
measures how frequently the wave passes
wavelength and frequency are
light propagates through space via alternating electric and magnetic fields
propagation of light
as light radiates away, its energy spreads out over a greater area causing the photons to appear fainter
the spreading of a beam of light into its different light waves according to its wavelength
the range of wavelengths or frequencies over which electromagnetic radiation extends (radio, microwave. infrared, visible, ultraviolet, x ray, gamma ray)
A decrease in the wavelength of radiation emitted by an approaching celestial body.
Energy of a photon is
proportional to its frequency
inversely proportional to its wavelength
scale with lowest theoretical temperature (absolute zero)
doesn't account for thermal motion
A hypothetical object that is a perfect absorber and emitter of radiation at all wavelengths
(blackbody curve) Shows relationship between the blackbodies intensity at every wavelength when heated to a given temperature
blackbodies peak wavelength is inversely proportional to its temperature
(the hotter an object is, the bluer it will appear)
even a slight increase in temperature leads to a huge increase in flux
hot objects radiate more at all wavelengths
The amount of light leaving a star per second (measured in watts)
The hotter or larger the star...
the more luminous
temperature and luminosity
luminosity is proportional to its temperature to the 4th power
luminosity is proportional to radius squared
Brightness of a star
proportional to luminosity
inversely proportional to distance squared
occupy all the space around the nucleus in a "cloud"
Bohr Model of Hydrogen
-model based on the electron in a hydrogen atom traveling around the nucleus in one of an array of concentric orbit. movement from a higher n level to a lower n level releases light.
the process in which a electron absorbs the photon and moves up an energy level (ex: N=2 to N=3)
The array of colors will be shown but it will be missing the absorbed photon's color- absorption lines
when an electron releases a photon/ or energy and moves back down an energy level (ex: N=4 to N=2)
Only the emitted photon's color will be shown through a prism- emission lines
Hydrogen atom quantized energy state
Each element has its own unique set of
electron absorbs enough energy to leave the atom
Emission lines from ionization
When an ionized electron finds another atom missing an electron, the electron then emits the original photon
when a hot, dense object's light passes through a prism it creates a
When a hot, dense object's light passes through a cloud of cool gas it creates a
When a gas is heated and then passed through a prism it creates a
waves compress to shorter wavelengths when in direction of motion, and stretch to longer wavelengths behind
Shorter wavelengths that are given as an object in space move toward an observer.
longer wavelengths that are given as an object in space moves away from an observer
How to tell if a star is coming toward or going away
find the change in wavelength (observed wavelength - rest wavelength)
If the value is negative (less than 0) it is blue shifted
If the value is positive it is red shifted
proportion to doppler shift (ex: if coming toward us at twice the speed, it will be blue shifted by twice its amount)
what makes up the sun
the center of the sun(unbelievably high pressure and where electromagnetic radiation is created)
carries energy via radiative diffusuion (Photons of light radiate from here and go on the "random walk" in this zone for a long time)
carries energy via convection (like boiling water)
"'surface" where the light escapes
"tiny" (the size of texas) convection cells in the photosphere and bring energy out
cooler and darker regions on photoshpere of Sun
(still very bright)
lower atmosphere of the sun
has a higher temperature than the photosphere
outer atmosphere of the sun
(seen through solar eclipse)temperatures are even hotter than chromosphere
the region in the Sun's atmosphere where the temperature rises very rapidly from the temperatures that characterize the chromosphere to the high temperatures of the corona
open magnetic field lines stretching out into space
- gasses then escape and form solar wind
caused by coronal holes and is 1 million mph
In order for an electron in a hydrogen atom to increase its energy level from n=2 to n=3 it must
absorb a photon with a wavelength of 656 nm
when light from a hot dense object passes through a prism a ________ spectrum is produced
When light from a hot dense object passes through a cloud of cool gas before it is passes through a prism, a ____________ spectrum is produced.
An atom is ionized when it _________ a photon of very __________ wavelength, causing the electron to leave the atom entirely.
If an electromagnetic wave's frequency is increased, then
its energy increases, the wavelength decreases, and its color gets bluer
The energy required to transition a photon from n=3 to n=5 in a hydrogen atom is ___________ the energy required to transition from n=5 to n=2
True or False: the Angstrom, nanometer, and meter are all used to measure wavelengths
As a blackbody become hotter, it also becomes _______ and ___________
more luminous and bluer
Star A and star B appear equally bright in the sky. Star A is twice as far away from Earth as star B. How do the luminosities of stars A and B compare?
Star A is 4 times as luminous as Star B (distance squared)
The temperature of an object has a very specific meaning as it relates to the object's atoms. A high temperature means that the atoms
are moving very fast
Twos stars are of equal luminosity. Star A is 3 times as far as star B. Star A appears ________ Star B
1/9 as bright as star B
When an electron moves from a higher energy level to a lower energy level
a photon is emitted
The transition region is only 50km thick, yet temperatures can suddenly jump from about 10,000 K in the _______________ to 1,000,000 K at the ____________
The Sun's photosphere is segmented into small (1000km) convective cells called
The sun's atmosphere is divided into:
the core, the radiative zone, the convective zone
The sun is mostly made up of
Charged particles escape from the sun via ________, forming the ____________.
coronal holes; solar wind
cooler regions of the photosphere (darker relative to the rest of the sun)
regions of magnetic activity
sunspots typically form in
Sunspots ___________ their latitude throughout their life cycle
Sunspots taper off near the
Sun is a solid body
The sun has multiple rotational periods:
it rotates _______ at the equator and _______ at the poles
Differential rotation of the sun
the equatorial regions of the sun rotating more rapidly than the polar regions.
What is a major reason why there is a continuous cycle of sunspots
When magnetic field lines twist and tangle up they occasionally will snap/pop forming
sunspots occur in a cycle of around _____ years
Huge loops of gas (can be very large)
violent, rapid erruptioms (magnetic field lines that reconnect and "short out")
solar min: 1 per week
solar max: 1 per day
CME (coronal mass ejection)
Large-scale solar event involving an ejection of hot plasma that may accelerate charged particles and travel as far as the Earth's orbit, preceded by a shock front that may create a magnetic storm on Earth - can be seen as an aurora (Northern Lights)
magnetic field lines that trap charged particles
prominences seen in silhouette (cooler and darker)
occurs in the core of the sun
protons normally repel each other but the pressure and temp in the core are so high that they fuse together instead
The ____________ is responsible for about 85% of Sun's energy
The balance between the gravity (pulling inward) and the pressure (pushing outward) of the sun
gamma rays radiated from the core go on a "random walk" in the radiative zone. It dilutes the radiation and makes the photons lose energy.
emerge from the sun right away (ninja particles)
Analyzes the sun's vibrations to determine its internal structure
the earliest stage of a star's life
- forming at center of collapsing molecular clous
- temp/pressure not high enough for fussion
a broad ring of material orbiting a protostar
flattened outer part of the disk that did not become part of the star
inner disk that feeds the protostar
distance of mass from axis:
T Tauri Stars
"late term' protostars
- aren't yet fusing H but will soon
- strong stellar winds
outflow (disk material) being channeled through the poles
high velocity jets that slam into and ionize interllar gas
way to detect exoplanets by measuring the lowered brightnessed due to the planet crossing the star
How to find orbital period using transit method
repeating drop offs in light signal a exoplanet. The time between drop offs is the orbital period
limiting factor of transit method:
requires a edge on view
artificially block out the sun's light to locate exoplanets
limiting factor of direct imaging:
only massive planets that are far away can be detective because those two small/close will be blocked out with the sun
planets that are tidally locked to their star and are slowly vaporizing
only a planet's ________ mass can be known if its _________ is unknown.
a _______ forms at the center of a circumstellar disk
What kinds of planets does the transit method detect most often
planets that are viewed from edge on to our line of sight
When does a protostar become a star?
when the temperature and pressure are high enough to ignite
in its core
What method of detecting exoplanets involves blocking the star's light?
what method of detecting exoplanets involves detecting periodic changes in a star's apparent brightness?
what method of detecting exoplanets involves detecting periodic changes in a star's doppler shift?
what method of detecting exoplanets is capable of detecting multiple planets in a system
all three (transit, direct, radial velocity)
Which two forces establish hydrostatic equilibrium in an evolving protostar?
pressure and gravity
Why do protostars blow their stellar winds in bipolar outflows?
The circumstellar disk confines the protostar's wind outflow to the poles
What do we need to know about a planet to determine if it is capable of supporting life?
distance from sun, atmospheric composition via spectroscopy
What kind of planets does the direct imaging method detect most often?
massive planets that orbit far from their host star
What kind of planets does the radial velocity method detect most often?
massive planets that orbit close to their host star
Why does a collapsing cloud flatten as it rotates?
the cloud rotates fastest at its equator, which pushes infalling material away
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