Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
138 Cards in this Set
- Front
- Back
|
Localized, blotchy dark colored regions on the photosphere?
|
Sunspots
|
|
|
What are three characteristics of sunspots?
|
1. 1500 K cooler than surrounding gas thus appearing dark
2. Strongly magnetic 3. Occur in pairs (with opposing polarity) |
|
|
Huge flame-like structures extending from the photosphere into the corona?
|
Prominences
|
|
|
What are three characteristics of prominences?
|
1. gas is both rising from and falling to the photosphere
2.Shape is defined by magnetic fields 3. Usually associated with sunspot pairs |
|
|
Brief energetic eruptions from the photosphere
|
Solar Flares
|
|
|
What are four characteristics of solar flares?
|
1. Occur near active regions
2. Eject streams of ionized gas into the corona 3. can eject material directly into the solar wind 4. Can produce high energy particles and intense radiation |
|
|
How long does it take for a solar cycle to complete?
|
22 years
|
|
|
The number of sunspots waxes and wanes during an ? year cycle then reverses polarity for the next ? years
|
11 and 11
|
|
|
The dark region of a sunspot is the ?
|
Umbra
|
|
|
The lighter colored region of a sunspot is the ?
|
Penumbra
|
|
|
What is the name of the diagram used to plot the latitude of a sunspot over time?
|
Maunder butterfly diagram
|
|
|
Astronomers can measure magnetic fields on the sun using the ? effect?
|
Zeeman effect
|
|
|
How is the Zeeman Effect demonstrated in the spectrum and why does this occur?
|
When there is a split of a single line into multiple components. This occurs because when an atom is in a magnetic field the electron orbits are altered and the atom is able to absorb a number of different wavelength photons
|
|
|
When observing the Zeeman effect how is the separation between components compared to the strength of the magnetic field?
|
The separation is proportional to the strength of the magnetic field
|
|
|
How do the spot locations on the Sun move during the solar cycle?
|
They migrate to lower latitudes
|
|
|
A term which describes the irregular sometimes explosive motions of gas and radiation on the Sun's surface
|
Solar activity
|
|
|
How is solar activity powered? 3 ways
|
1. The sun's luminosity
2. Differential rotation 3. Twisted magnetic fields |
|
|
Name the sun's interior structure going inwards
|
photosphere, convective zone, radiation zone, core
|
|
|
The visible solar "surface" where light last interacts with matter? It is less than 500 km thick
|
Photosphere
|
|
|
The region where blobs of plasma continuously rising and sinking carry the Sun's energy to the photosphere
|
Convective zone
|
|
|
the zone that is stable and where energy streams through as photons
|
Radiation zone
|
|
|
The region that is 200,000 km in radius where energy is liberated by fusion of hydrogen into helium
|
Core
|
|
|
What are the elements that make up the majority of the sun's composition? What are their percentages respectively?
|
Hydrogen, Helium
91%, 8% |
|
|
How does fusion effect the elements present in the sun's core?
|
It decreases Hydrogen and increases Helium
|
|
|
How does temperature and density on the sun change as you move inwards?
|
Both increase significantly. from 5800 K at the surface to 15 million K at the center
|
|
|
How old is the sun estimated to be?
|
4.6 Billion years old
|
|
|
The theory developed by astrophysicists employing various elements of physics to define the change of temperature, pressure, density, composition, and gas motions with radius within the sun
|
Standard Solar Model
|
|
|
What three observations create a fixed standard solar model?
|
1. The solar constant
2. The sun's radius 3. The surface composition |
|
|
The two ways we use to test the standard solar model?
|
Helioseismology and Neutrinos
|
|
|
The study of the sun which uses specialized telescopes to measure the different ringing sounds thus providing data on the interior
|
Helioseismology
|
|
|
Ghostly particles produced by fusion reactions in the core which escape and can be observed here on Earth
|
Neutrinos
|
|
|
The process by which the sun's luminosity is produced
|
Nuclear fusion
|
|
|
This occurs when the nuclei of light elements combine into heavier elements. i.e. hydrogen into helium
|
Fusion
|
|
|
In a fused nuclei how is the mass in relation to the sum of the masses of the lighter elements from which they formed?
|
They are less in mass
|
|
|
How is energy liberated according to Einstein?
|
E(liberated)=(change)MC^2
|
|
|
Where does fusion occur and why?
|
In the cores of stars because the process only occurs at immense temperatures and pressures.
|
|
|
A series of three nuclear reactions that build a helium atom by adding together protons; It is the main energy source of the sun
|
Proton-Proton chain
|
|
|
How is energy released during fusion? What spectrum of light does this produce at the photosphere?
|
It is released in the form of Gamma-Rays and becomes visible light at the photosphere
|
|
|
What are the names of the two additional atomic particles created during fusion
|
Positrons and neutrinos
|
|
|
A form of antimatter which are positively charged electrons?
|
Positrons
|
|
|
The almost mass less "ghost" particles which don't interact with other matter.
|
Neutrinos
|
|
|
The predicted number of neutrinos emitted by the sun according to the standard solar model is 3 times the observed. This is known as the ?
|
Solar Neutrino problem
|
|
|
What is the action and range that gravity has on the universe?
|
Action: Always attractive
Range: infinte |
|
|
This shapes the universe. All masses respond to this force and it keeps planets and stars in orbit
|
Gravity
|
|
|
Represents the forces between charged particles. Charge can be positive or negative
|
Electromagnetism
|
|
|
What is the action and range that electromagnetism has in the universe?
|
Action: both attractive and repulsive
Range: infinite |
|
|
This force binds positively charged nuclei of atoms together?
|
Strong Nuclear Force
|
|
|
What is the Action and range of a strong nuclear force?
|
Action:attractive
Range: 10-15 meters |
|
|
This force controls emission of radiation and particles from radioactive materials.
|
Weak nuclear force
|
|
|
What is the action and range of a weak nuclear force?
|
action: Attractive
Range: 10-15 meters |
|
|
The apparent change in the position of an object due to a change in the location of the observer.
|
Parallax
|
|
|
How is parallax measured?
|
It is measured in seconds of arc where 1 sec of arc equals 1 parasec
|
|
|
What is the distance of 1 pc equal to in AU and light years respectively?
|
AU= 206,265
Light year=3.26 |
|
|
How far is the nearest star away from Earth?
|
1.3 parasecs or 4.3 ly
|
|
|
The rate at which a star moves across the sky; measured in seconds of arc per year
|
proper motion
|
|
|
The component of an objects velocity that is directed toward or away from earth.
|
Radial velocity
|
|
|
The true space velocity is a combination of what two variables?
|
Proper motion and radial velocity
|
|
|
How is the radii of stars determined? using Luminosity-radius-temperature relationship
|
L ∞ R^2*T^4 ( ∞ means is proportional to)
|
|
|
Stars range in size from ? to ?
|
.01R to 500R
|
|
|
Small stars are known as what?
|
dwarfs
|
|
|
Larger stars are known as what?
|
Giants or Supergiants
|
|
|
How is the color of a star related to surface temperature?
|
They are directly related
|
|
|
What are the color ranges from coolest to hottest?
|
It ranges from red as the coolest to Blue which is the hottest
|
|
|
What are the temperature ranges for stars?
|
Range form 3000K which would be a red star to blue-white stars which are 50,000 K
|
|
|
How is the apparent brightness of a star related to the intrinsic (true) luminosity and the distance?
|
It is proportional to the true luminosity and inversely proportional to the square of its distance.
|
|
|
Intrinsic brightness of a star; the apparent visual magnitude the star would have if it were 10 pc away
|
Absolute magnitude
|
|
|
How are stars classified?
|
According to the characteristics of their spectra
|
|
|
What are the two ways astronomers use the absorption lines in optical spectra to group stars?
|
According to the pattern and strength of the absorption lines which are a sequence of surface temperature.
|
|
|
What are the spectral classes in order from hottest to coolest
|
O,B,A,F,G,K,M
|
|
|
A category of stars of similar luminosity; determined by the widths of lines in their spectra
|
Luminosity class
|
|
|
Which stars within a spectral class are most luminous? Least luminous?
|
Supergiants-most
dwarfs- least |
|
|
Which stars are the most massive? Least massive?
|
O dwarfs-most massive
M dwarfs-least massive |
|
|
How is the composition of stars determined?
|
By analysis of the lines in their spectra
|
|
|
All stars are composed primarily of what two elements? what are their percentages?
|
Hydrogen 76% by mass
Helium 22% 2% all others |
|
|
How does the initial mass of a star predetermine the lifetime of that star?
|
More massive stars burn fuel faster and live shorter lives while less massive stars have a longer lifetime as their fuel burns slower
|
|
|
What is the average lifetime of an "O" star?
G dwarf? M dwarf? |
O star- 3-10 million years
G dwarf- 10 billion years M dwarfs- up to a trillion |
|
|
The name of the diagram which plots the intrinsic brightness versus the surface temperature of stars; it separates the effects of temperature and surface area on steller luminosity; commonly absolute magnitude versus spectral type but also luminosity versus surface temperature or color
|
Hertzsprung-Russell diagram
|
|
|
In the Hertzsprung Russell diagram what defines the X and Y axis?
|
Color(temperature) defines the X-axis and Brightness (Luminosity) defines the Y-axis
|
|
|
What does the observational HR diagram plot?
|
It plots the brightness of stars in magnitudes versus color
|
|
|
What does the theoretical HR diagram plot?
|
It plots luminosity (in solar units) vs. stellar surface temperature (in Kelvin)
|
|
|
The region of the H-R diagram running from upper left to lower right which includes roughly 90 percent of all stars
|
Main sequence
|
|
|
Large cool highly luminous star in the upper right of the H-R diagram, typically is up to 100 times the diameter of the sun
|
Giants
|
|
|
Exceptionally luminous star 10-1000 times the size of the sun
|
Supergiants
|
|
|
The remains of a dying star that has collapsed to the size of Earth and is slowly cooling off; It is at the lower left of the H-R diagram
|
White dwarfs
|
|
|
The sun is classified as where on the H-R diagram?
|
It is a G2 dwarf and it located on the main sequence
|
|
|
Stars range in luminosity from ? to ?
|
10^-4 to 10^4 L
|
|
|
What defines the initial location of a star on the H-R diagram?
|
The mass of the star
|
|
|
As stars evolve what two characteristics change forcing them to move around on the H-R diagram
|
Luminosity and Temperature
|
|
|
The gas and dust distributed between stars
|
Interstellar Medium
|
|
|
How dense is the gas and dust that makes up the interstellar medium?
|
Extremely low density
|
|
|
What are the elements that make up the atoms and molecules of the interstellar gas? (8)
|
H,He,O,N,C,S,Si,Fe
|
|
|
Microscopic solid grains in the interstellar medium which are made up of light and heavy elements which are tens to thousands of atoms lumped together.
|
Interstellar dust
|
|
|
The regions of space where glass and dust clouds are made visible?
|
Nebulae
|
|
|
The type of nebula where dark regions of gas and dust where the dust absorbs starlight passing through the region
|
absorption nebulae
|
|
|
A cloud of glowing gas excited by ultraviolet radiation from hot star this type of nebula are often red in appearance due to light from hydrogen atoms
|
Emission nebulae
|
|
|
How does dust extinct starlight?
|
By absorbing photons of light as they pass through
|
|
|
How does dust redden starlight?
|
By the preferential absorption of blue light compared to the longer wavelength redlight
|
|
|
A nebula produced by starlight reflecting off dust particles in the interstellar medium. These appear blue
|
reflection nebula
|
|
|
What are the two ways dust clouds are made visible?
|
1. By absorbing radiation from hot stars embedded within the clouds.
2. By vast stellar explosions which light up the gas |
|
|
What are the four classifications of emission nebulae?
|
1.HII regions
2. Stellar Bubbles 3. Supernova Remnants 4. Planetary nebulae |
|
|
A region of ionized hydrogen around a hot star caused to glow by UV radiation from young, hot O&B stars
|
HII region
|
|
|
Blobs of hot gas caused to expand and glow by the action of power stellar winds
|
Stellar bubbles
|
|
|
Hot gases blowing outward from the surface of a star. the equivalent for another star of the solar wind
|
stellar wind
|
|
|
The expanding shell of gas marking the site of a supernova explosion. These blobs are extremely hot gas caused to glow as the explosion debris collides with surrounding gas
|
Supernova remnants
|
|
|
An expanding shell of gas ejected from a star during the final dying phase of a star. These remnants are non-explosive and is illuminated by the UV radiation from the very hot core of the star
|
Planetary nebulae
|
|
|
How do the spectra of dust clouds differ from that of stars?
|
Their spectra show bright emission lines of common elements like Hydrogen
|
|
|
What two ways can gas clouds which are not lit up by nearby hot stars be studied?
|
1.They can be studied by the absorption lines which are produced in the background stars shining through the nebulae.
2. By 21cm radiation produced by cold hydrogen atoms. |
|
|
What part of the spectrum observes 21 cm radiation which is produced by cold hydrogen atoms?
|
The radio part of the spectrum
|
|
|
In the dense regions of the ISM most of the gas exists in what form? Why?
|
Molecular form due to the extremely cold temperatures
|
|
|
What is the name of the dense regions which are considered the nurseries of stars?
|
Giant Molecular Clouds
|
|
|
GMCs are observed in what two parts of the EM spectrum?
|
1. Infrared due to dust
2. Radio due to molecules |
|
|
What temperatures exit in the interstellar medium?
|
It is complex consisting of hot, warm, cool, and cold.
|
|
|
Which temperature is interstellar medium generally more dense?
|
Cold gas and dust is more dense
|
|
|
What is the dominant force which drives star formation. Interstellar gas and dust clouds collapse into themselves as a result of this force?
|
Gravity
|
|
|
contracting lumps of gas and dust within cold molecular clouds that form stars are called?
|
protostars
|
|
|
How are protostars traced as an evolutionary track using the HR diagram?
|
By the change in temperature and luminosity with time
|
|
|
When a gas cloud becomes a star and the central density and temperature are sufficiently high enough to ignite nuclear reactions the star is said to be on which part of the HR Diagram?
|
Main Sequence
|
|
|
True or False
The time required for a star to be born depends on its mass? Why? |
True, more massive stars take a much shorter time to reach the main sequence
|
|
|
True or False
White dwarfs are collapsing gas clouds that may never reach nuclear ignition? |
False these are called brown dwarfs and only recently have been discovered
|
|
|
Which two portions of the EM spectrum are used to study star-forming regions?
|
Infrared and Radio
|
|
|
True or false
Scientists use UV light to study star forming regions? |
False, Scientists use infrared and radio because the dust mixed with gas absorbs the shorter wavelength UV and optical light
|
|
|
This telescope is designed to open new windows on our understanding of the physics of star and planet formation
|
SIRTF or the Space Infrared Telescope Facility
|
|
|
In cloud to star formation what three characteristics result from each stage
|
Smaller, warmer, denser
|
|
|
How many stages are there in the cloud to star process
|
six
|
|
|
How long does it take for sun-like stars to complete stages 1-6
|
Approx. 10 million years
|
|
|
True or false
Sirius is the brightest star in the sky. If we moved it 10 times further away it would look 1/100 as bright |
True because luminosity varies with the inverse of distance^2
|
|
|
True or false
Two stars that look very different must be made of different elements. |
false, The most common element in the universe is hydrogen. Instead stars look different due to size, varying surface temperature, and distance
|
|
|
True or false
Stars that appear blue are cooler than stars that are red |
false stars that are red are cooler
|
|
|
True or false
Stars emit light mostly from their surfaces. |
True, photospheres
|
|
|
True or false
Heat flows from cool to hot regions |
false, heat flows from hot to cool regions
|
|
|
True or false
Hotter stars radiate more energies at higher frequencies |
true
|
|
|
True or false
A stars temp can be roughly estimated from its color |
True
|
|
|
true or false
Black body radiators are generally hot |
true
|
|
|
True or false
Hotter stars have a longer maximum intensity wavelength |
False, they have a shorter wavelength, therefore a higher frequency
|
|
|
true or false
Temperature is a measure of the heat produced by a star |
false, Temperature is the average velocity of random motions by atoms or molecules in a material
|
|
|
true or false
when astronomers refer to the temp of a star they are talking about the gases in the photosphere |
True
|
|
|
The name for the electromagnetic radiation emitted by a heated object
|
black body radiation
|
|
|
true or false
The hotter an object is the more motion among its particles |
true
|
