Test 2 / Midterm Flashcards
spectroscopy
the study of the interaction between matter and radiated energy; the measurement of radiation intensity as a function of wavelength
What is light?
wave of something in the electric field and the magnetic field
electric field
makes electric forces work
magnetic field
makes magnetic forces work
Which two scientists worked together to form spectroscopy? What two tools did they use?
Kirkoff - spectroscope
Bunsen - Bunsen burner
What did Kirkoff and Bunsen do?
They put various things in a Bunsen burner and watched through a spectroscope.
What two fields oscillate back and forth to make a wave? How so?
magnetic and electric
large positive > zero > large negative > zero > large positive > zero > large negative > zero…
What color has the longest wavelength?
red
What color has the shortest wavelength?
blue/violet
What are the characteristics of a red wave? (wavelength, frequency, energy)
long wavelength, low frequency, less energy
What are the characteristics of a blue wave? (wavelength, frequency, energy)
short wavelength, high frequency, more energy
frequency
number of times per second that a wave hits you
longer waves hit less often; shorter waves hit more often
Frequency is measured in ____.
Hertz
high frequency = ____ energy
more
low frequency = ____ energy
less
What are the characteristics of radio waves? (wavelength, frequency, energy)
long wavelength, low frequency, less energy
What are the characteristics of gamma waves? (wavelength, frequency, energy)
short wavelength, high frequency, more energy
How much energy do ultraviolet waves produce in relation to other waves?
a lot (hence sunburns), more than infrared but less than gamma rays
In modern astronomy, how much of the electromagnetic spectrum is used?
all
The formation of the three types of spectra are addressed in ____ Rules.
Kirkoff’s
What are the three types of spectra?
continuous, emission/bright line, absorption/dark line
Describe continuous spectra.
like a full rainbow, no discontinuous or stark changes
Describe emission/bright line spectra.
does not emit light; bright, narrow lines of color; opposite of absorption
Describe absorption/dark line spectra.
opposite of emission; looks like a continuous spectrum with lines missing
What is Kirkoff’s first rule? (How is a continuous spectrum produced?)
A continuous spectrum is produced when you have hot solid, hot liquid, or hot compressed gas.
ex. incandescent lightbulb; sun’s core
What is Kirkoff’s second rule? (How is an emission line spectrum produced?)
Emission line spectra are produced by hot thin gas. The wavelengths (colors) of the emission lines depend on the chemical compound.
ex. Sodium burns yellow.
What is Kirkoff’s third rule? (How is an absorption line spectrum produced?)
You must have a continuous spectrum first passed through a cool (lower temperature than whatever caused the continuous spectrum) thin gas. Wavelengths reflect the composition of the cool thin gas not whatever caused the initial continuous spectrum.
The sun is hotter in its ___ than its ____ ____.
core; outer atmosphere
What is the spectral result of the sun’s core being hotter than its outer atmosphere?
The core is the continuous spectrum source and the outer atmosphere provides a cool thin gas to create an absorption spectrum.
You must have a ____ spectrum before you can have an absorption line spectrum.
continuous
Can you tell what element is involved by the continuous spectrum?
no
Who figured out the structure of the atom?
Neils Bohr
What did Bohr determine about atoms in relation to element identification?
The number of protons in an atom’s nucleus determines the element.
Electrons orbit the ____ at different levels.
nucleus
Can an electron orbit the nucleus between levels?
no
Can an electron jump from one orbital level to another?
yes
To jump from a lower level to a higher level, an electron needs more ____.
energy
Where does an electron obtain the energy needed to jump to higher levels?
the electron absorbs photons of light
What type of spectrum is produced when an electron jumps to a higher level? Why?
absorption line spectrum
the photon/wavelength of light disappears because it was absorbed by the electron
What type of spectrum is produced when an electron jumps down a level? Why?
emission line spectrum
When it jumps down, it emits a wavelength of light and releases energy.
In what direction is the light from an electron emitted?
random
not necessarily in the same direction it was absorbed from
Every element has its own unique set of ___ levels.
energy
Each element emits and absorbs a different amount of ___.
energy
The Doppler effect applies to ___ and ____.
sound; light
Doppler effect
higher pitch means it is moving toward you; lower pitch means it is moving away from you
What are the characteristics of a high pitch sound? (frequency, wavelength)
higher frequency, shorter wavelength
What are the characteristics of a low pitch sound? (frequency, wavelength)
lower frequency, longer wavelength
What happens during a blueshift?
whole pattern shifted toward shorter wavelengths
What happens during a redshift?
whole pattern shifted toward longer wavelengths
Closer stars’ spectral patterns are shifted towards ___.
blue
This is not enough to actually affect the color of the star.
Farther stars’ spectral patterns are shifted towards ___.
red
This is not enough to actually affect the color of the star.
Why are telescopes placed on mountaintops?
to be above the atmosphere
less light pollution
What are the three function of an astronomer’s telescope?
1- Light gathering power
2- Resolving power
3- Magnifying power
What is the least important function of a telescope?
magnifying power
What is the most important function of a telescope?
light gathering power
Telescopes: ____ power is not worth it if you do not have good ____ and ____ power.
Magnifying power is not worth it if you do not have good resolving and light gathering power.
Before you get a large image, you must first have a quality image.
resolving power
image clarity
good- sharp
bad- fuzzy
second most important telescope function
light gathering power
allowance to gather or collect light to view faint/faraway objects
most important telescope function
What determines the magnifying power of a telescope?
focal length or eyepiece
Resolving power is determined by the main ____ or ___.
mirror; lens
If a telescope’s lens is doubled in diameter, you can see things that are ___ as big.
half
Lens diameter is directly related to…
what size objects you can see
If a telescope’s lens diameter is increased more than about 20 inches, the resolving power is determined by ____ _____.
Earth’s atmosphere
How does the Hubble telescope achieve better resolving power?
It is positioned above Earth’s atmosphere.
What is the formula for the area of a circle?
πr^2
Telescopes are like funnels in order to…
collect more light
If you double the diameter, the area increases by ___.
4
The light gathering power of a telescope depends on the….
square of the diameter
Resolving power depends on the ____.
diameter (of the main lens)
The diameter of the main mirror/lens determines the ____ ____ power and the ____ power.
light gathering; resolving
Lenses ____ and mirrors _____.
Lenses refract and mirrors reflect.
Refracting telescopes use ____ lenses.
convex (curves outward, as opposed to concave)
refract
light bends
focal length
distance from lens to focal point (eyepiece)
Formula: magnifying power =
focal length / distance to object
If a lens is heavy, it will…
sag or curve
What are the 2 primary disadvantages of a refracting telescope?
1- Limit to how big you can make them
2- Very expensive
What are the 2 types of reflecting telescopes?
Newtonian Design
Cassegrain Design
What are the 2 main features of a reflecting telescope?
eyepiece
prime focus configuration
What are 2 benefits of a reflecting telescope?
very large telescope
puts astronomer at eyepiece
Describe a Newtonian Design telescope.
low cost, cheap, good quality
has secondary mirror
Describe a Cassegrain Design telescope.
eyepiece at bottom for ease of use
What is the most common type of large telescope?
Cassegrain Desgin
Describe a Schmidt Cassegrain telescope.
a little more expensive (than Cassegrain), better image quality, correcting lens
What is the structure of a refracting telescope?
Rays from distant point source=======>LENS—(focal length)—>eyepiece (focal point)
Studying the sun helps us understand ____ ___.
other stars
The mass of a star can be determined using what?
Kepler’s 3rd law (as modified by Newton)
planets orbiting the star or binary system orbits
Many stars are in ___ orbits.
binary (2 stars orbiting each other)
A star’s energy output depends on ___ and ____.
temperature; distance
What is the formula to determine the surface area of a sphere?
4πr^2
To determine a star’s energy output, you must know…
how bright it appears to be and distance
Luminosity is measured in…
watts (Joules per second)
luminosity
how much energy is put out per second
What is the sun’s energy output?
3.8 * 10^26
A red star is ___ than a blue star.
cooler
A star’s colors tells us its approximate ____.
temperature
Where a star’s brightness peaks (on the color spectrum) is directly related to ___ and nothing else.
temperature
How does the sun get its energy?
nuclear fusion
How hot is the sun?
6000º K
E=mc^2
energy = mass * (speed of light)^2
In Einstein’s E=mc^2, ____ and ____ are interchangeable.
energy; mass
What is the speed of light?
186000 miles per second
3 * 10^8 meters per second
nuclear fission
something (such as heavy elements or heavy atoms) splitting and releasing energy
What is the sun’s composition?
98% H and He
2% every other element
nuclear fusion
lighter elements combing to make heavier elements
The sun, at its start, had enough H fuel to last ___ years. It has ___ years left.
10 billion; 5 billion
What is the process of the sun’s nuclear fusion?
4 H atoms make 1 He atom
that difference in mass is converted to energy according to E=mc^2
High density forces repel protons together
Where do the sun’s nuclear fusion reactions take place?
in the core
What is the purpose of a convection current on the sun?
transfers heat to its surface
Sun: granules
bubbles from convection currents
Sun: corona
very thin gas only visible during solar eclipse
What are the four parts/layers of the sun?
core, photosphere, chromosphere, corona
Who discovered sunspots? When?
Galileo; 1610
sunspots
areas of sun that are a little cooler
where convection currents are not going or where energy is passing over
Sunspots have very strong ___ fields.
magnetic
Sunspots deflect ___ currents.
convection
Different colored areas of the sun indicate a difference in ___.
temperature
solar flare
brighter regions of the sun
Sunspots and solar flares are directly related to the sun’s ___ field.
magnetic
When sunspots and solar flares are present, the sun is ___.
active
How long is a solar activity cycle?
about 11 years
solar minimum
few sunspots or solar flares
slightly lower luminosity
solar maximum
lots of sunspots or solar flares
slightly higher luminosity
Describe a solar activity cycle.
(1-4 years) solar minimum -> (next 5-11 years) solar maximum -> (next 1-4 years) solar minimum -> (next 5-11 years) solar maximum -> (next 1-4 years) solar minimum…
coronal mass objectives
material flying out of sun
could interact with Earth’s magnetic field
What causes the Northern Lights?
coronal mass objectives
The Little Ice Age
1650s - 1680s
very few, virtually no sunspots
solar minimum
Medieval Grand Maximum
1000 AD; more sunspots than normal
What causes global warming?
greenhouse effect caused by too much CO2 in the atmosphere
The ___ of the sun can affect Earth’s climate.
luminosity
Is the brightness of a star in a photo related to the size of the star?
nope
For a red star and a blue star to be of equal brightness, the red star must be ___ than the blue star.
bigger
What do absorption lines in a star’s spectrum tell you about the star’s temperature?
nothing
If you know the luminosity and apparent brightness of a star, you can find the ____.
distance
parallax
closer objects appear to move more than faraway objects
helps determine a star’s angular diameter and its distance from Earth
heliocentric parallax
the parallax of a celestial star using two points in the Earth’s orbit around the sun as the baseline
helps determine a star’s angular diameter and its distance from Earth
parsec
an astronomical unit of distance derived by the theoretical annual parallax (or heliocentric parallax) of one arc second, and is found as the inverse of that measured parallax; equal to 3 lightyears
Brightness is measured in _____
magnitude
The sun’s brightness is equal to ___ magnitude.
-27
The brighter the star, the ___ the magnitude.
lower
A 20th magnitude star is ___ than a 1st magnitude star.
fainter
A 1st magnitude star is ___ times as bright as a 2nd magnitude star.
2.5
A 3rd magnitude star is ____ times as faint as a 1st magnitude star.
(2.5)^2 = 6.25
Stars we can see with the naked eye are between ___ and ___ magnitude
1 and 6
mass
number of kilograms
Size is determined using ___ and ___.
diameter and length
If size is bigger, is mass bigger?
not necessarily
the larger object could be hollow or have low density
On an H-R Diagram, where are white dwarfs?
bottom left
On an H-R Diagram, where are red giants and red super giants?
top right
super giants above giants
On an H-R Diagram, where is the main sequence?
curvy line from top left to bottom right
On an H-R Diagram, what is the horizontal axis?
temperature or spectral type; highest -> lowest
On an H-R Diagram, what is the vertical axis?
luminosity or absolute visual magnitude; negative numbers (more luminous) ^ 1 (Sun) ^ positive numbers (less luminous)
How do you determine the luminosity of a star?
with size and temperature
or apparent brightness and distance
How do you determine the mass of a star?
Kepler’s 3rd law; orbits of stars; measured in kilograms; not equal to size
Kepler’s 3rd law
There is a mathematical relation between period (time it takes to orbit sun) and distance from sun (au).
p^2 = K * a^3
or p^2 = a^3 if K=1
p=period; a=distance between sun and planet
K involves mass of sun
How do you determine the temperature of a star?
color; spectrum
red = cool
blue/white/violet = hot
Mass is usually measured in relation to the ____.
Sun
If the sun is 1, a star of 10 solar mass is 10 times the mass of the sun.
Absorption lines depend on the ___ ___ of the star.
chemical compostion
The H-R Diagram was created simultaneously and independently by
Hertzsprung (Dutch) & Russell (American)
List the spectral classes of stars in order.
O B A F G K M - R N S
What is the temperature range of the spectral classes?
O is the hottest, S is the coldest
Which spectral class of star as the weakest H absorption lines?
S
Which spectral class of star has the strongest H absorption lines?
A
Is the strength of a star’s H absorption lines related to the amount of H it contains?
no
Who first classified stars by spectra?
Annie Jump Cannon
Who discovered that strong H absorption lines do not mean more H?
Cecilia Payne-Gaposchkin
What do strong H absorption lines depend on?
temperature
O is too ___ to have H absorption lines.
hot
At ____ºK, A is just the right temperature to show H absorption lines.
10,000
Why doesn’t M have H absorption lines?
M doesn’t have enough (heat) energy to bump electrons up to the right level (2) to have H absorption lines.
All stars have the same chemical composition of…
70% H, <30% He, 2% other
The H absorption lines that the spectral classification system is based on result from a ____ effect.
temperature
Every element has its required ____ to produce absorption lines.
temperature
A class stars produce ___ absorption lines.
H
B class stars produce ___ absorption lines.
He
G and K class stars produce ___ absorption lines.
elemental metals
Goldilocks Range
perfect distance from a star to support life
ex. Earth
Absolute Visual Magnitude
luminosity
On an H-R Diagram, a positive number is ____ luminous than a negative number.
less
Where is the sun on the H-R Diagram?
middle of main sequence
Describe a white dwarf.
Hot, low luminosity, small in size (about the size of earth)
Describe a red giant/supergiant.
cool, large in size, high luminosity
How small (solar mass) can a star be and still generate adequate energy?
1/10 the mass of the sun
or .1 solar mass
How massive (solar mass) can a star be and remain stable?
100 times the mass of the sun
or 100 solar mass
What is the sun’s solar mass?
1
cluster of stars
group of stars related to one another in space
An open cluster is also know as a ____ cluster.
galactic
How old are stars in an open or galactic cluster?
Relatively young
Describe an open/galactic cluster.
Spread out, individual stars are visible, about 100 stars, usually young
How old are stars in a globular cluster?
Rather old (10-12 billion years, around since the formation of the Milky Way)
When were stars in a cluster formed in relation to one another?
About the same time
Describe a globular cluster.
Stars densely packed in center, like a glob, individual stars only visible on the outer edges, about 100000 stars
What holds a globular cluster together?
Gravity
Nebula
Leftover dust after formation of stars
What does the presence of a nebula tell you?
The nearby stars are very young.
Parallax is used to determine a star’s…
angular diameter and distance from Earth.
The ___ massive stars usually leave the main sequence and become red giants first.
most
More massive stars age ____.
faster
The more massive a star is, the ___ its main sequence lifespan will be.
shorter
The less massive a star is, the ___ its main sequence lifespan will be.
longer
Why do more massive stars evolve faster?
They burn through their H fuel faster in order to maintain their high temperatures and high luminosities.
Do more massive or less massive stars have more H fuel?
more massive
A star of 10 solar mass has __ times the H fuel, but it burns it ______ times as fast, because it puts out ______ times as much energy.
A star of 10 solar mass has 10 times the H fuel, but it burns it 10000 times as fast, because it puts out 10000 times as much energy.
What is the coolest layer/part of the sun?
photosphere
6000ºK
A star’s temperature is determined using…
color or spectral classification
How many years does the sun have left?
5 billion
Strong H absorption lines mean the star is…
at the optimal temperature to produce H absorption lines.
