ASTR 1000 Unit 2 test

If a star were 375 light years away, what would be the parallax angle of this star in arc-seconds? (Don't enter units)

0.00869

Consider two new stars (C and D). Both stars have the same intrinsic luminosity but Star D is at a distance 5.58 times further away than Star C. From Earth, how will the apparent brightness of Star D compare to Star C?

0.0321

Rank the order of the initial steps that the interior layers of a star leaving the main sequence starting with (1) the core initially running out of hydrogen and ends just before the star is a (temporarily) stable star fusing helium in its core. 1.) The core initially runs out of hydrogen 2.) Hydrogen fusion begins in a shell around the inert helium core. 3.) The decreased fusion rate in the hydrogen fusing shell allows the outer layers of the star to shrink back down. 4.) The helium flash in the core expands the hydrogen fusing shell and reduces the hydrogen shell fusion rate. 5.) The fusion rate in the hydrogen shell heats the star's outer layers and causes them to expand. 6.) The inert helium core reaches 100 million K, triggering the helium flash. 7.) The inert helium core and inert hydrogen shell shrink and heat up

1,3,7,6,4,5,2

Rank the order of the initial steps that the interior layers of a star in the later parts of the red giant phase starting with (1) a (temporarily) stable star fusing helium in its core and fusing hydrogen in a shell. 1.) The star is temporarily stable as helium fusion occurs in the core and hydrogen fusion in a shell around the core. 2.) Outside the degenerate carbon core a shell of helium shrinks and heats up. 3.)The inert carbon core shrinks and is eventually only supported by degeneracy pressure. 4.) Helium fusion begins in a shell around the inert carbon core. It is a double shell burning star. 5.) The exposed core emits UV light which excites the recently expelled gases, causing them to glow. 6.) The helium in the core is all fused into carbon and core fusion ceases. 7.) Continually increasing stellar winds eventually begin to eject the outer layers in shells of expanding gases.

1,4,3,5,7,2,6

Rank the different layers that make up the Sun and its atmosphere from the central region of the Sun (1) to the most outer layer of the Sun's atmosphere (6). Core Corona Photosphere Radiation Zone Chromosphere Convection Zone

1,6,4,2,5,3

Two more stars (E and F). In the night sky, Star F appears 3.41 times brighter in the sky than Star E, but parallax measurements show that Star F is 19.8 times further away than Star E. Given this information, how does the luminosity of Star F compare to Star E?

1.34×103

Star A and Star B are the same distance from the Earth, but Star B is 12.09 times more luminous than Star A. From Earth, how will the apparent brightness of Star B compare to Star A? (Brightness of B/Brightness of A, no units)

12.1

Star A has a surface temperature of 4600 K. Star B has a surface temperature of 6100 K. Star B has a radius that is 9.11 times the radius of Star A. How does the luminosity of Star B compare to the Luminosity of Star A? (The luminosity of Star B over the luminosity of Star A)

257

Object | Parallax Angle (arcseconds) Star A | 0.153 Star B | 0.292 Star C | 0.066 Star D | 0.389 Star A Star B Star C Star D

3, 2, 4, 1

If there were some slight increase in the core temperature of the Sun, a series of events would occur to restore the balance called gravitational equilibrium. List the following events from the first one just after the slight temperature increase (1) to the last event just before the original core temperature is restored (4). Core expands and cools. More energy is produced, increasing pressure. Rate of fusion decreases Protons collide with more energy, increasing the fusion rate.

3,2,4,1

I measure the parallax angle of a star to be 0.241 arcseconds, what is the distance to the star in parsecs? (don't enter units)

4.15

Another star has a parallax angle of a star to be 0.075 arcseconds, what is the distance to this star in light years? (don't enter units)

43.5

Star C has a surface temperature of 4200 K. Star D has a surface temperature of 5800 K. Star D has a luminosity that is 18690 times the luminosity of Star C. How does the radius of Star D compare to the radius of Star C? (The radius of Star D over the radius of Star C)

71.7

Consider the following methods of generating energy in stars. For each of the stages of stellar evolution below, identify the primary method of generating energy. A Gravitational contraction B CNO cycle of hydrogen fusion in core C Proton + electron -> neutron + neutrinos D Proton-proton chain hydrogen fusion in core E Helium capture in many concentric shells Protostar High mass main sequence star Low mass main sequence star Supernova Supergiant

A, B, D, C, E

What would you most likely find if you returned to our solar system in 10 billion years? A.) A white dwarf B.)The Sun as it appears now (the Sun won't change significantly over the next 10 billion years) C.) A neutron star D.) A brown dwarf E.) A black hole

A.) A white dwarf

What causes a planetary nebula to glow? A.) Emission from the expelled gases excited by the UV radiation from the newly exposed stellar core. B.) Radiation from the nucleosynthesis of heavy, unstable elements in a supernova. C.) Thermal radiation from planets that are destroyed by an expanding red giant star. D.) Reflection of a white dwarf's light by surrounding interstellar dust grains.

A.) Emission from the expelled gases excited by the UV radiation from the newly exposed stellar core.

Based on the types of stars present, which of the following star clusters is youngest? A.) The cluster contains main sequence stars of all spectral types except O, and a few giants and supergiants. B.) The cluster contains main sequence stars of spectral types K and M, some giants and some white dwarfs. C.) The cluster contains main sequence stars of all spectral types except O and B, and a few giants and supergiants. D.) The cluster contains no main sequence stars, a few giants, and a lot of white dwarfs. Incorrect The cluster contains only white dwarfs.

A.) The cluster contains main sequence stars of all spectral types except O, and a few giants and supergiants.

What would happen if the core of the Sun could not expand when the fusion rate increased. Incorrect The extra heat energy would quickly be radiated away from the surface and equilibrium would be restored. A.) The core would heat up, and the fusion rate would continue to increase at a runaway rate. B.) The rotation rate of the Sun would increase and the temperature would decrease. C.) The core temperature would slightly decrease and find a new lower temperature equilibrium. D.) The core temperature would slightly increase and find a new higher temperature equilibrium.

A.) The core would heat up, and the fusion rate would continue to increase at a runaway rate.

If positive charges repel each other, what keeps the two protons in the nucleus of helium together? A.) The strong force is the only force in nature that can overcome the electrostatic repulsion of protons in close proximity. B.) Since protons are so much more massive than electrons, the gravitational force between two protons is sufficient to overcome any electrostatic repulsion. C.) Because the protons are moving at the speed of light, Einstein's energy (the E in E=mc2) compensates for the electrostatic repulsion. D.) The electrostatic force is only a repulsive force when the particles are far apart; when close together, the force is actually and attractive force pulling protons together.

A.) The strong force is the only force in nature that can overcome the electrostatic repulsion of protons in close proximity.

What is the approximate chemical composition (by mass) that all new stars are born with? A.) Three quarters hydrogen, one quarter helium, and at most 2% heavier elements. B.) Half hydrogen, half helium. C.) 95% hydrogen, 4% helium, and at most 1% heavier elements. D.) 98% hydrogen, 2% helium. E) 98% hydrogen, 2% elements heavier than helium.

A.) Three quarters hydrogen, one quarter helium, and at most 2% heavier elements.

Which one statement about the giant molecular clouds in which stars form is FALSE? A.)They are primarily made up of complex molecules, like methane, ammonia and water. B.) Although they are still a vacuum by any laboratory standard here on Earth, they are much denser than other regions of interstellar space. C.) They are very cold (about 10-30K). D.) They are many times more massive than the average star.

A.)They are primarily made up of complex molecules, like methane, ammonia and water.

Match the luminosity class to the characteristic(s) that best describes it. [Do not consider the complications that would arise if any of these stars were in binary systems.] A White dwarf stars B Supergiant and giant stars C Main sequence stars 1.) These stars have exhausted their supply of hydrogen fuel in their cores but continue to generate energy by other means. 2.) These stars are much more luminous than the Sun. 3.) These stars are the most common. 4.) These stars are the rarest. 5.) These stars no longer support any kind of nuclear fusion. 6.) These stars are typically the size of the Earth. 7.) In this class, a star's mass is directly related to its temperature and its luminosity. 8.) These stars are hot and dim.

B, B, C, B, A, A, C, A

Why do extremely high temperature stars (like type O) not show strong hydrogen absorption lines? A.) Due to their high temperatures in these stars we see hydrogen emission lines rather than absorption lines. B.) At such high temperatures the Hydrogen atoms become ionized, completely losing their electrons, leaving nothing behind in the hydrogen atom to make spectral lines. C.) These stars have burnt off all of their hydrogen so there is no hydrogen left in the star. D.) Even at these temperatures the star will not be hot enough to initially excite the electrons out of the ground state into the n=2 state where they can make spectral lines in visible wavelengths.

B.) At such high temperatures the Hydrogen atoms become ionized, completely losing their electrons, leaving nothing behind in the hydrogen atom to make spectral lines.

Which one of the following statements about white dwarfs is FALSE? A.) The gravitational contraction of white dwarf stars is halted by the outward push of the electron degeneracy pressure. B.) More massive white dwarfs are larger in size. Incorrect White dwarfs are primarily composed of carbon or sometimes oxygen. C.) If white dwarfs accrete hydrogen from a companion star, it can begin to fuse on the surface of the white dwarf, causing a nova. D.) White dwarfs are generally about the size of the Earth.

B.) More massive white dwarfs are larger in size.

Which one of the following statements about brown dwarfs is FALSE? A.) Their cores never reach the minimum temperature for hydrogen to fuse into helium. B.) The have masses between 0.5 and 0.1 times the mass of the Sun. C.) They may significantly outnumber ordinary stars. D.) They are dim and radiate most of their energy in the infrared part of the spectrum.

B.) The have masses between 0.5 and 0.1 times the mass of the Sun.

Which one of the following statements about neutron stars are FALSE? A.)The masses of neutron stars are expected to range from 1.4 - 3 solar masses. B.) The reason neutron stars rotate so fast is because they come from high mass main sequence stars, which are known to rotate very rapidly. C.) The escape velocity from the surface of a neutron star would be around half the speed of light. D.) In neutron stars the gravitational collapse is halted by the outward push of the neutron degeneracy pressure. E.) Neutron stars are typically the size of a city

B.) The reason neutron stars rotate so fast is because they come from high mass main sequence stars, which are known to rotate very rapidly.

The best computer models that replicate the changes in the number and latitude of sunspots throughout the sunspot cycle do so by combining __________. A.) magnetic fields and Kepler's Laws B.) the Sun's magnetic fields, rotation and convection Incorrect the Sun's rotation and the conservation of angular momentum C.) nuclear fusion and convection D.) radiative transfer and the three types of neutrinos E.) nuclear fusion and gravitational contraction

B.) the Sun's magnetic fields, rotation and convection

Many names used by astronomers are misleading or outdated. A good example is the term planetary nebula, which astronomers use to refer to _______. A.) a globular cluster, which looks like a planet through very small telescopes B.) the shell gradually let go by a dying low-mass star C.) the remains of an exploded high-mass star D.) a solar system in formation E.) a region of gas and dust where new planets have recently formed

B.) the shell gradually let go by a dying low-mass star

Match the term with the description provided. A Coronal mass ejections B Solar flares C Coronal holes D Solar prominences E Sunspots 1.) Regions of the corona that barely show up in X ray images because they are nearly devoid of hot coronal gas. 2.) Vaulted loops of hot gas that rise above the Sun's surface, following magnetic field lines. 3.) Blotches on the surface of the Sun that appear darker because they are cooler. 4.) Huge bursts of charged particles from the Sun's corona that travel outward into space. 5.) Large and sudden releases of energy on the Sun's surface, probably caused when energy stored in magnetic fields is released.

C, D, E, A, B,

Which statement about protostar formation is FALSE? A.) Protostars often end up orbiting each other in binary or multiple star systems. B.) A protostar initially heats up as contraction converts gravitational potential energy into thermal radiation. C.) A protostar is born when the core temperature is high enough for hydrogen fusion. D.) Protostars in late stages are often violent, emitting strong winds and high speed jets.

C.) A protostar is born when the core temperature is high enough for hydrogen fusion

In massive stars the core goes through stages of fusion of different elements (hydrogen, helium, carbon, and so on). Which of the following patterns is FALSE? A.) At the end of each stage the core shrinks and the core temperature increases. B.) When the core runs out of an element to fuse, that element will start to fuse in a shell around the core. C.) Each successive stage lasts for approximately the same amount of time. C.) Each successive stage lasts for approximately the same amount of time. D.) Each stage produces elements with higher atomic numbers and atomic masses.

C.) Each successive stage lasts for approximately the same amount of time.

Which of the following statements about nuclear fusion and nuclear fission is TRUE? A.) Fission of light nuclei into heavier nuclei generates energy for all elements heavier than iron. B.) Fusion of heavier nuclei into lighter nuclei generates energy for all elements lighter than iron. C.) Fusion of light nuclei into heavier nuclei generates energy for all elements lighter than iron. D.) Fusion of light nuclei into heavier nuclei generates energy for all elements heavier than iron. E.) Fission of heavier nuclei into lighter nuclei generates energy for all elements lighter than iron.

C.) Fusion of light nuclei into heavier nuclei generates energy for all elements lighter than iron.

Which statement best describes the observed pattern of the abundances of atoms with atomic numbers between Z=6 and 20? A.)The abundances are all approximately the same. B.) The abundances are completely random. C.) The abundances generally decrease with increasing atomic number, but the elements with even atomic numbers tend to be more abundant than elements with odd atomic numbers. D.) The abundances generally increase with increasing atomic number, but the elements with odd atomic numbers tend to be more abundant than elements with even atomic numbers. E.) The abundances generally decrease smoothly with increasing atomic number.

C.) The abundances generally decrease with increasing atomic number, but the elements with even atomic numbers tend to be more abundant than elements with odd atomic numbers.

Which one of the following statements about measuring distances using stellar parallax is FALSE? A.) In order to use this method to determine star distances we must first know the distance from the Earth to the Sun. B.) All stars have parallax angles that are less than one arc-second. C.) This technique is useful for measuring the distances to galaxies as well as stars. Incorrect A parsec is a unit of distance equivalent to 3.26 light years. D.) If we know a star's distance from parallax and the apparent brightness we can calculate its luminosity using the inverse square law for light.

C.) This technique is useful for measuring the distances to galaxies as well as stars.

You want to plot the position of a star on the H-R diagram. You will need to measure all of the following quantities except the star's ___________. A.) distance B.) spectral type C.) mass D.) apparent brightness

C.) mass

Which of the following main sequence stars is the most numerous? A.) type O stars B.) type F stars C.) type M stars D.) type G stars E.) type A stars

C.) type M stars

Match the layer of the Sun to the description given. 1. This region has the highest density, pressure, and temperature of any place in the Sun. 2. Energy is transported through this region as hot material bubbles up and cool material sinks down. 3. Energy is transported through this region as high energy photons repeatedly scatter off of free electrons in random directions and gradually work their way outwards. 4. The visible surface of the Sun. 5. The only location in the Sun where fusion is occurring.

Core, Convection, Radiation, Photosphere, Core

Match the different properties of our current understanding of nuclear fusion in stars with the observed patterns of the elemental abundances (from the chart above) that provide evidence that supports our current understanding. A After the big bang hydrogen and helium were the only atomic nuclei and at the end of a star's life, most of the original hydrogen and helium in the stars has not undergone any fusion as the fusion reactions only occur in or near the core. B Elements more massive than iron are only produced in supernova events. C Helium capture reactions are efficient ways of fusing heavier elements (ex. He + C -> O, He + O -> Ne, etc.) and produce elements that have atomic numbers that are +2 higher. D Two helium nuclei won't fuse together. Helium fusion occurs through three helium nuclei fusing via the triple alpha process. 1.)While the abundance of helium (He, Z=2) and carbon (C, Z=6) are both fairly high, the abundances of lithium (Li, Z=3), beryllium (Be, Z=4), and boron (B, Z=5) are all very low. 2.) The abundances of hydrogen (H, Z=1) and helium (He, Z=2) are much higher than any other element. 3.) The pattern of abundances of elements with atomic numbers between Z=6 and 20 found in the previous part. 4.) The abundances of elements with atomic numbers greater than Z=30 are all much less than the abundances of elements between Z=6 and 20.

D, A, C, B

Which one of the following statements about a high mass supergiant is FALSE? A.) Helium capture is one simple fusion reaction in a supergiant in which helium nuclei fuses into another nucleus, increasing the atomic number by +2. B.)The core of a supergiant contains multiple layers of fusion reactions towards the end of its life. C.) Once an iron core forms, the supergiant has about one day before it goes supernova. D.) At the end of the supergiant's life, most of the star's original hydrogen and helium has been converted to heavier elements. E.) Each time the core depletes the elements it is fusing, it shrinks and heats up until it becomes hot enough for other fusion reactions.

D.) At the end of the supergiant's life, most of the star's original hydrogen and helium has been converted to heavier elements.

Why do lower temperature stars (like type G,K,M) not show strong hydrogen absorption lines? A.) Due to their low temperatures in these stars we see hydrogen emission lines rather than absorption lines. B.) These stars have burnt off all of their hydrogen so there is no hydrogen left in the star. C.) At such low temperatures the Hydrogen atoms become ionized, completely losing their electrons, leaving nothing behind in the hydrogen atom to make spectral lines. D.) At these lower temperatures the star will not be hot enough to initially excite the electrons out of the ground state into the n=2 state where they can make spectral lines in visible wavelengths.

D.) At these lower temperatures the star will not be hot enough to initially excite the electrons out of the ground state into the n=2 state where they can make spectral lines in visible wavelengths.

Which of the following about spectral types of stars is not generally true? A.) The spectral type of a star can be determined by identifying lines in its spectrum. B.) The spectral type of a star can be used to determine the star's surface temperature. C.) The spectral type of a star can be used to determine the overall color of the star. D.) The spectral type of a star can be used to determine the distance from the Earth to the star.

D.) The spectral type of a star can be used to determine the distance from the Earth to the star.

Magnetic field lines represent the direction of a magnetic field and are drawn closer or further apart to represent the strength or weakness of the magnetic force. What happens when charged particles in the solar atmosphere encounter magnetic fields? A.) They easily move across magnetic field lines but not along magnetic field lines. B.) They behave as if there was nothing there; magnetic fields do not affect charged particles. C.) They almost immediately stop moving. D.) They move in a spiral pattern along the magnetic field lines.

D.) They move in a spiral pattern along the magnetic field lines.

What is the relative abundance (by number) of the number of oxygen atoms to the number of hydrogen atoms in the galaxy? A.) abundance of oxygen 1/1,000,000 that of hydrogen B.) abundance of oxygen 1/100 that of hydrogen C.) abundance of oxygen 1/100,000 that of hydrogen D.) abundance of oxygen 1/1,000 that of hydrogen E.) abundance of oxygen 1/10 that of hydrogen

D.) abundance of oxygen 1/1,000 that of hydrogen

Why does helium fusion require a higher temperature than hydrogen fusion? A.) Because helium has an atomic mass that is higher than hydrogen, so it is more massive than hydrogen. B.) Because helium nuclei are much larger in size than hydrogen nuclei, so they must be pushed together a greater distance. C.) Because the degeneracy pressure in the inert helium core does not allow the core to expand as it heats up. D.) Because the strong force only becomes an attractive force at temperatures over 100 million K. E.) Because each helium nucleus contains two protons, so the repulsion between helium nuclei is much stronger than the repulsion between hydrogen nuclei.

E.) Because each helium nucleus contains two protons, so the repulsion between helium nuclei is much stronger than the repulsion between hydrogen nuclei

As a star becomes a giant, its outer layers are expanding. Where does the energy for expanding these layers initially come from? A.) From the long-term fusion of hydrogen into helium in the core. B.) From an explosion in the core called the "helium flash". C.) From a magnetic dynamo effect in the star's outer layers, caused by a much stronger magnetic field inside the star. D.) From the fusion of helium into carbon in the core. E.) From the fusion of hydrogen into helium in a shell around the core.

E.) From the fusion of hydrogen into helium in a shell around the core.

What is the correct order of the spectral classes from hottest to coldest? A.) MKGFABO. B.) OBAGKFM. C.) MGKABFO. D.) OBGFAMK. E.) OBAFGKM. F.) ABFGKMO.

E.) OBAFGKM.

Which of the following statements is FALSE? A.) The average density of the Sun is similar to the density of water. B.) The Sun is not "on fire" or powered by any chemical reactions. C.)The Sun's diameter is approximately 100 times greater than the diameter of the Earth. D.) The Sun is composed of about 70% hydrogen, 28% helium, and 2% heavier elements. E.) The Sun is approximately one billion times the mass of the Earth.

E.) The Sun is approximately one billion times the mass of the Earth.

Most stars are born with the same basic composition. However stars can have different luminosities and different surface temperatures. Which two factors primarily determine the physical characteristics of a star? A,) Its luminosity and its apparent brightness B.) Its age and its location in the galaxy C.) Its distance and apparent brightness D.) Its mass and its surface temperature E.) The star's mass and its stage of life

E.) The star's mass and its stage of life

All stars begin their lives with essentially the same basic composition. What property of a forming star primarily determines how they will differ? A.) the color they formed with B.) the amount of time they take to form C.) the luminosity they formed with D.) the location where they were formed E.) the mass they formed with

E.) the mass they formed with

Stars A and B have the same luminosity but star A has a higher surface temperature than star B. Which of the following statements must be true based on this information? 1.) Star A has a larger mass than star B. 2.) Star A has a larger radius than star B. 3.) The two stars have different spectral types. 4.)Star A has a smaller radius than star B. 5.) The two stars have the same spectral type.

FALSE, FALSE, TRUE, TRUE, FALSE

Identify the following statements about luminosity classes as either TRUE or FALSE. 1.) High mass main sequence stars live much longer than low mass main sequence stars because they have so much hydrogen to burn. 2.) Most stars have luminosities that are much lower than our Sun's luminosity. 3.) Although it is possible to have a star that is one million times more luminous than the Sun, most stars have luminosities equivalent to our Sun's luminosity. 4.) The absorption lines in a star's spectrum can be used to determine the star's luminosity class. 5.) The luminosity class of a star tells us something about a star's radius.

FALSE, TRUE, FALSE, FALSE, TRUE

Identify the following statements about the 1.) In E=mc2, "E" is the energy released by nuclear fusion and "m" is the mass of all of the protons involved. 2.) The proton-proton chain reaction can be summarized as follows: 4(1H) → 4He + Energy + neutrinos 3.) Neutrinos are produced in nuclear reactions in the core of the Sun, can escape the Sun's core, and can be observed from the Earth. 4.) One helium atom has exactly the same mass as four hydrogen atoms. 5.) The Sun shines by nuclear fission, which is the chemical burning of hydrogen. 6.) Protons interact and fuse with other protons at ordinary room temperatures.

FALSE, TRUE, TRUE, FALSE, FALSE, FALSE

Identify the following statements about the evolution of low mass stars as either TRUE or FALSE. 1.) When the core of the star first runs out of hydrogen the star's luminosity and radius decrease, and it's surface temperature increases. 2.) The red giant stage lasts a much shorter time than the main sequence stage in low mass stars. 3.) When helium fusion begins in the star it will begin in the core surrounded by a hydrogen fusing shell. 4.) The helium flash will cause the luminosity and radius of the star to decrease. 5.) Helium fusion requires a higher temperature and density than hydrogen fusion.

FALSE, TRUE, TRUE, TRUE, TRUE,

Which of the following would cause the rate of fusion in the core of the Sun to increase? 1.) An increase in the core radius. 2.) A decrease in the core temperature. 3.) A decrease in the core radius. 4.) An increase in the core temperature.

False, False, True, True

For each of the descriptions provided identify the spectral type that most closely matches. 1.) Stars of this type are most similar to our Sun. 2.) The hottest stars that we see. Very rare. 3.) These stars have the lowest surface temperatures of all stars. 4.) These stars have very strong absorption lines due to ionized metals like Calcium. 5.) These stars have very strong absorption lines due to hydrogen. 6.) These stars show wide absorption bands due to the presence of molecules. 7.) Stars with this spectral type will have a spectrum that has peak emissions far into the ultraviolet part of the spectrum.

G, O, M, G, A, M, O

Below is a table of data for five Main Sequence Stars: Star Luminosity (L/LSun) Spectral Type Altair 10.7 A7 Kruger 60 0.010 M2 Tau Ceti 0.59 G8 Zeta Ophiuchi 68,000 O9.5 Epsilon Eridani 0.37 K2 Match the star with the description provided: Kruger 60: Which star has the longest main sequence lifetime? Kruger 60: Which star has the smallest radius? Zeta Ophiuchi: Which star has the highest core fusion rate? Zeta Ophiuchi: Which star has the highest core temperature? Zeta Ophiuchi: Which star is most massive?

KRUGER, KRUGER, ZETA, ZETA, ZETA

Where on the Hertzsprung-Russell diagram would you find stars with the following properties? 1.) Stars that are cool and dim 2.) The highest mass main sequence stars 3.) White dwarfs 4.) Stars with the largest radii 5.) Red giant stars

LOWER RIGHT, UPPER LEFT, LOWER LEFT, UPPER RIGHT, UPPER RIGHT

An astronomer is analyzing a spectrum of light from a star. They notice many strong spectral lines clustered in bands due to molecules such as titanium oxide (TiO). What can they infer from this analysis. 1.) This star must be relatively cool, because otherwise these molecules would move too fast and break apart into atoms. 2.) This star contains much more titanium and oxygen than the average star. 3.) This star must be very massive, because only massive stars have enough internal pressure and the high core temperatures to fuse these heavy elements. 4.) This star probably emits more light in the infrared than it does in the ultraviolet part of the spectrum. 5.) This star must be well advanced in age to have manufactured so much oxygen (atomic number 8) and titanium (atomic number 22).

TRUE, FALSE, FALSE, TRUE, FALSE

Identify the following statements about the evolution of high mass stars as either TRUE or FALSE. TRUE: Fusing iron nuclei yields no energy. FALSE: The reaction that powers the supernova explosion is the fusion of iron atoms into even heavier elements. FALSE: In a galaxy like our own, supernova are expected to occur at least a couple of times per year. TRUE: The mass of the dead star (neutron star or black hole) left at the end of the star's life is significantly less than the mass of the original main sequence star. TRUE: In a high mass main sequence star, hydrogen is fused into helium via the CNO cycle.

TRUE, FALSE, FALSE, TRUE, TRUE

Identify the following statements about the sunspot cycle as TRUE or FALSE. 1.) The average number of sunspots on the Sun rises and falls in an approximate 11-year cycle. 2.) If the Sun is at a solar maximum this year, in 11 years it will be at a solar minimum. 3.) During each cycle, the magnetic poles of the Sun reverse. 4.) During the solar maximum the overall luminosity of the Sun increases significantly. 5.) During a solar maximum, about 50% of the Sun's surface is covered with sunspots.

TRUE, FALSE, TRUE, FALSE, FALSE

Identify the following statements about star formation as either TRUE or FALSE. 1.) When a single giant molecular cloud undergoes gravitational collapse it will form many star systems. 2.) Giant molecular clouds with higher temperatures will more easily undergo gravitational collapse. 3.) A high mass protostar takes less time to turn into a main sequence star than a low mass protostar. 4.) Protostars are powered by energy released from gravitational contraction. 5.) It is more common for high mass protostars to form than low mass protostars.

TRUE, FALSE, TRUE, TRUE, FALSE

Which of the following statements are TRUE about a red giant that has evolved from a one solar mass main sequence star? 1.) Its surface is cooler but overall it is more luminous than when it was a main sequence star. 2.) Throughout the red giant phase it is in constant gravitational equilibrium. 3.) Its core is hotter than it was when it was a main sequence star. 4.) Its stellar winds become very strong and it eventually loses some of its mass. 5.) Carbon fusion starts in a shell around an inert helium core. 6.) Helium fusion starts in a shell around an inert hydrogen core.

TRUE, FALSE, TRUE, TRUE, FALSE, FALSE

Stars A and B have the same surface temperature but star A has a higher luminosity than star B. Which of the following statements must be true based on this information? Star A has a larger radius than star B. The two stars have different spectral types. The two stars have the same spectral type. Star A has a larger mass than star B. Star A has a smaller radius than star B.

TRUE, FALSE,TRUE, FALSE, FALSE

Identify the following statements about measuring the properties of stars as either TRUE or FALSE. 1.) I can directly measure the apparent brightness of a star. I cannot directly measure the star's luminosity. 2.) In order to measure the mass of a star it must be in a binary or multi-star system. 3.) The greater a star's parallax angle the greater the distance to the star. 4.) Astronomers determine the radius of a star by measuring it directly from the size it appears in photographs. 5.) Astronomers determine the luminosity of a star by measuring its temperature and measuring its radius, and then using the equation Luminosity = 4πσ·Temperature4 Radius2.

TRUE, TRUE, FALSE, FALSE, FALSE

Identify the following statements about solar activity as either TRUE or FALSE. 1.) Coronal holes are a major source of solar wind. 2.) If a strong coronal mass ejection hits the Earth there may be disruptions in electrical power and radio communications. 3.) Solar prominences are formed by large looping magnetic field lines. There are typically sunspots where the magnetic field lines enter the surface of the Sun. 4.) Strong solar winds can cause interference that can weaken auroras. 5.) Sunspots appear darker than the rest of the Sun's surface because they block some of the sunlight from the photosphere.

TRUE, TRUE, TRUE, FALSE, FALSE

In a double shell red giant star what elements are fusing in the outermost shell? the innermost shell?

hydrogen, HELIUM