Astronomy Part 1 Section 2 Flashcards
What is the Lyman Series?
An example of jumps between specific levels in hydrogen atoms. Lyman jumps between level one and other levels
What type of photon is associated with Lyman Series?
Ultraviolet Photons
What is the Balmer Series?
An example of jumps between specific levels in hydrogen atoms. Balmer series jumps between level two and higher levels.
What type of photon is associated with Balmer series?
visual and UV photons
How is an aspectral line produced?
it is produced by many electrons undergoing a particular transition in a particular type of atom
When a source of sound wave approaches an observer, the pitch is higher or lower?
higher
Define the doppler shift
The wavelength of light from a moving source is shifted
Describe what happens to the wavelength when a source is approaching?
Wave crests are closer together, they have a shorter wavelength, a blue shift
Describe what happens to the wavelength when a source is receding?
The wave crests are further apart, the wavelengths are longer, there is a red shift
what is the doppler formula?
V/C = observed wavelength - wavelength at rest/ wavelength at rest
Describe the sun
The sun is a typical star, a self gravitating sphere of hot gas, the sun is middle aged
What percentage of the mass of the solar system is the sun?
> 99%
If halllow, how many earths could the sun hold?
About 10^6 earths
What is Luminosity?
Luminosity is the energy output per time
What is the sun’s luminosity?
Lo = 4 x 10^26
How much does the earth intercept of the sun’s energy output?
10^-9
What is the surface temperature of the sun?
T = 5,800 K
What occurs in the sun’s core?
nuclear fusion
The sun is always in __________ equilibrium
hydrostatic equilibrium
What is hydrostatic equilibrium?
outward gas pressure force balances the inward force of gravity. The sun essentially supports its own weight. the pressure below each layer of the sun must support the weight of that layer plus the weight of the gas above it
What is thermal equilibrium?
energy radiated from the photosphere of sun is replaced by internal energy release
How long could oxidation power the sun?
only for a few thousand years
What does an ionized state mean?
electrons are stripped from the nuclei
Is the gas in the sun in a ionized state?
yes
What is nuclear fusion?
combination of nuclei to produce heavier nuclei with a release of energy
When does fusion occur?
only when the nuclei move fast enough to overcome electrical repulsive force, requires temp > 10^7 K
Describe what and how hydrogen fusion occurs
4 hyrdogen nuclei fuse to form one helium nucleus. 4H —> 1He + energy.
What does einstein’s formula say about hydrogen fusion?
part of the mass is converted to energy
How much of the mass of H is converted to energy?
0.7%
How long can hydrogen fusion power the sun?
For another 5 billion years
What is the constellation Taurus also known as?
“The Bull”
Describe the constellation Taurus
It is high in the south in the evening, nearly overhead. Head has a V shape. The brightest star is Aldebaran which means “the follower”. It follows the Pleiades star cluster in the sky. It is also called “the eye of the bull”, It has a red giant star, it has a faint red binary companion.
according to the standard solar model what is the central density of the sun?
1.6 x 10^5 kg/m^3
How much of the sun’s mass is within the inner half of the radius?
90%
What is the central temperature of the sun?
1.6 x 10^7 or 16 million K
What is the surface temperature of the sun?
5800 K
What are two types of energy transportation?
radiation and convection
What is radiation?
photons randomly walk outward
What is convection?
rising currents of hot gas carry heat outward, sinking currents of cool gas replace the hot gas
Where does radiation dominate in regards to the sun?
In the core and inner envelope
Where does convection dominate in regards to the sun?
In the outer envelope where the gas is cooler
Describe the layers of the sun
the atmosphere, photosphere, chromosphere, transition zone, corona, solar wind
What is the photosphere?
also known as the light sphere, source of most visible radiation from sun, typical temp is 5800 K, only a few hundred Km thick, contains sunspots
What is granulation, or granules?
regions of bright an dark gas in the photosphere, provides evidence for convection
Bright regions are _____, _____ gas columns
hotter, rising
Dark regions are ______, _______ gas columns
cooler, sinking
What is the chromosphere?
also known as the color sphere, it is above the photosphere , about 1500 km thick, low density gas, temperature reaches about 4500 K and then increases outwards, red color, visible during solar eclipse, contains spicules
What are spicules?
jets of hot gas shooting outwards
What is the transition zone?
narrow region above the chromosphere where the temperature rises quickly above 10^6 K, energy of heat gas is transported outward by waves in the sun’s magnetic field
What is the carona?
few million km thick, very hot, low denisty gas, emits x rays, also visible & UV
What is the carona?
few million km thick, very hot, low denisty gas, emits x rays, also visible & UV
What are sunspots?
cooler regions in photosphere, emit less light than surrounding areas, size of the earth or larger, regions of strong magnetic field which blocks heat flow, usually appear in groups, last about two months
How long did Galileo discover the rotation of sun is?
4 weeks
The average number of sun spots varies with in a period of how many years?
11 years
What is the sunspot cycle caused by?
An interaction between the sun’s rotation and magnetic field
Does the sun rotate fast at the equator or a the poles?
the equator
What causes the solar cycle?
the sun rotates faster at the equator, which twists up and amplifies the magnetic field. The sun becomes more active as the field strengthens, it then breaks down every 11 years
what is a prominence?
a looping region of hot gas extending into the corona, supported by by magnetic field loop that pops out through the sunspots
what is a flare?
a violent release of energy and particles from a small region in the solar atmosphere, results from magnetic field instability.
What is solar wind?
stream of mostly protons and electrons escaping from the corona. They flow out through the solar system and reach the earth in a few days. Some particles are trapped in the earth’s magentic field
What is the aurora an example of?
An effect of solar wind on the earth’s solar storms. particles getting trapped by the earth’s magnetic field
What is the constellation Cassiopeia also known as?
The queen of Ethiopia
Describe the constellation Cassiopeia
It is in the shape of a W or a M on the opposite side of polaris from the Big Dipper, circumpolar, the milky way runs through it. Has a supernova remnant.
What is the SOHO spacecraft?
Solar and Heliospheric observatory, orbits the sun at L1 equilibrium point between the earth and the sun. Located 0.01 AU from the earth, continuously monitors electromagnetic radiation from sun and particles in solar wind. Gives advanced warning of solar storms.
What is a neutrino?
A very low mass, neutral particle, travels near the speed of light, interacts very weakly with matter.
How is a neutrino created?
When a proton is converted into a neutron in nuclear fusion, it escapes directly from the sun’s fusion zone.
How do we detect solar neutrinos?
most neutrinos pass right through the earth. We have neutrino telescopes, we use large water tanks deep underground. The neutrinos interact with water nuclei, the light flashes from interactions, and we record them
What is the solar neutrino problem?
Early neutrino experiments only detected about 1/3 of the solar neutrinos originally predicted.
What are the three types of neutrinos oscillated?
electron, muon, tau
Describe the MINOS experiment
A muon neutrino beam is shot from a Fermilab to another lab. Fewer muon neutrinos are received than emitted, indicating that neutrinos oscillate.
What is a parallax?
An apparent shift of object due to a change of viewpoint
Define a stellar parallax
p = 1/2 of apparent shift of star as the earth moves from one side of it’s orbit to another. Usually measured in an arcsec
What is the formula for stellar parallax?
d= 1/p
What is the ideal gas law and its corresponding formula?
Obey by normal gases. PV = N k T p = pressure v= volume t= temperature (in K) N = # of gas particles k = Boltzmann's constant
What happens to PVT when one uses an air pump?
the volume is reduced, the pressure is increased, the temperature is increased
What happens to PVT when you are using a gas thermometer?
The pressure varies directly with the temperature
What happens to PVT when a can is crushed
the temperature remains constant, the pressure remains equal to the external pressure and the volume varies directly with the number of gas particles
What happens with a balloon?
N is constant, the volume varies directly with the temperature, as the air balloon cools the volume must decrease
What is the Constellation Auriga also known as?
The Charioteer
Describe the constellation auriga
It is nearly overhead in the evening, has a pentagon shape, brightest star is called capella or “the goat star”, has a yellow star, has a similar spectrum to the sun,
what is the difference between luminosity and apparent brightness?
luminosity is energy per time radiated by a star, apparent brightness is energy per time per area received at earth
What is the inverse square law?
measures the apparent brightness, B = L/d^2
What is the stellar temperature for IR, Visable and UV?
3,000K, 6,000K, 12,000K
Hot stars emit what color? Cool stars emit what color?
Hot stars emit blue light, Cool stars emit red light
What is the Spectral Sequence?
Special classification based on absorption lines. O B A F G K M
What is a typical stars H + He composition?
75% H
23% He
< or equal to 2% other
Do hot stars show ionized H or He?
He
Do cooler stars show molecules?
Yes
Can you draw the Hertzsprung Russell Diagram?
plot of luminosity versus spectral class or surface temp for a group of stars LOOK AT THE DIAGRAM
What is a stars life cycle also known as?
Stellar evolution
What are the basic stages for the sun?
protostar, main sequence, red giant, white dwarf
How can you determine a stars mass?
Apply Newton’s laws of motion and gravity to binary star systems
