Chapter homework
21. 7. The evolutionary track for a star of 1 solar mass remains nearly vertical in the H-R diagram for a while (see Figure 21.12). How is its luminosity changing during this time? Its temperature? Its radius?
In the vertical region diagram, the luminosity is dropping while the surface temp remains constant. In this stage the materials of the star is falling inward without any hindrance. Due to how the star has less and less surface of the area with then gives off radiation. The luminosity is then decreasing together with the radius.
15. 20; TQ If you were concerned about space weather and wanted to avoid it, where would be the safest place on Earth for you to live?
I would want to live by the equator which is further away from the weak points of the poles.
8. 10. One method to measure the diameter of a star is to use an object like the Moon or a planet to block out its light and to measure the time it takes to cover up the object. Why is this method used more often with the Moon rather than the planets, even though there are more planets?
Because, it is used to know how rapid the moon moves into the orbit of the Earth. It is a possibility to calculate the diameter of the star.
18. 8 How do we distinguish stars from brown dwarfs? How do we distinguish brown dwarfs from planets?
Brown dwarfs are considered as failed stars. Due to how there mass is bigger and fused with deuterium and burns, lithium. The light that emits is due to how it contracts and it cools which make brown dwarfs glow in the infrared, as it releases gravitational energy. On the other hand, stars glow due to the release of the amount of energy due to the fusion of the reactions. Meaning the brown dwarfs are fainter than starts.
16. 23 TQ Give some everyday examples of the transport of heat by convection and by radiation.
By heat would be Boiling water, when the stove is turned on, it heats up the bottom of the container, as it heats up the water. As soon as the water gets heated it rises up. This is an example of convection heating of layers in the water. Melting Ice, This is an example of convection, if the ice cube is in room temperature, the air around it will heat the ice up causing it to melt. An air conditioning, when the Ac is on, hot air is around and get cooled by the compresser of it. By radiation Vacuum flask, which it helps maintain the temperature of tea, coffee, water and other types of warm fluids for a long time. It's not 100% efficient due to how it can lose some heat (radiation). It's a really slow process that takes time to lose the heat. Helping it keep the warm temp for hours. Heat coming from a fireplace, this is because of the radiation of the heat that goes throughout all directions. So if things are around it, it gets heated. Feeling the warmth of it. Heating food in the microwave oven, Heating by the mechanism of radiation. Sitting in the sun, sitting outside during a cold sunny day, the warmth of the Sun is by radiation heat. The energy of the sun is radiated to the person's skin.
20. 18. Describe the spectrum of each of the following:
starlight reflected by dust; Dust clouds reflect light that is coming nearby stars. They don't emit from energy in the infrared part of the spectrum. a star behind invisible interstellar gas, and; They are clouds behind the star, blocking it's light. As they produce absorption lines in the visible light of the spectra of stars an emission nebula; It's very small and cold. It can't radiate from visible radiation, so the absorption is visible and ultraviolet radiation, becoming hotter to the redations as emission in the infrared region.
18. 2 Name and describe the three types of binary systems
- Visual Binary, which is when two components are telescopically resolved. - Spectroscopic Binary, it's when components are not easily seen, but do have an indication by a periodic variation in velocity - Eclipsing Binary, it's when a star is blocked by the light of another star that is passing by
7.11 List some reasons that the study of the planets has progressed more in the past few decades than any other branch of astronomy.
-The development of advanced instruments and the apparatus meaning, that we have advance on how we developed our telescopes and the ability of being able to observe objects that are far away in the region of the galaxies - High advanced technology have made the astronomical studies less time consuming with exceptional results - Also, how spacecrafts and rockets have been launched in various planet orbits, it helps us collect and analyze information we need to get information about the planets.
18. 10 We discussed in the chapter that about half of stars come in pairs, or multiple star systems, yet the first eclipsing binary was not discovered until the eighteenth century. Why?
. It was due to how there wasn't any advanced technology to be able to study the spectrum of the star.
24. 4 If a black hole itself emits no radiation, what evidence do astronomers and physicists today have that the theory of black holes is correct?
1 star is from a binary system that is invisible, X-rays emission is by the accretion disk
17.6. Name five characteristics of a star that can be determined by measuring its spectrum. Explain how you would use a spectrum to determine these characteristics.
1. Temperature, according the Wien's law, by the signatures of spectral lines giving the temperature of the star 2. Chemical Composition, for when two stars that have identical temp and pressure, stronger lines meaning that there are more atoms in the stellar photosphere absorbing light. 3. Atmospheric pressure, when the spectra of stars have the same temp,but very different atmospheric pressure It can affect the spectrum in two ways. 1, There more collision in the star. 2. The ionized atoms have different spectra that are neutral. 4. Radial Velocity, the doppler effect must be considered for moving stars with respect to the earth. If the star is moving away then the spectral lines of the moving stars are shifting towards the red spectrum. If the star is moving towards the earth, then all the spectral lines of the moving star is being shift toward the blue line. The shift is greater than the fast moving star. Along the line of sight between the star and observer calling it radical velocity. 5. Rotation, the speed of rotation of a star also measured by using the Doppler effect, due to how the lines in the light that comes from the side of the star rotating towards the observer.
19. 2. Suppose you have discovered a new cepheid variable star. What steps would you take to determine its distance?
1st, locate the star, 2nd measure it by the period of it. 3rd Use the period of the luminosity of the relationship to be able to calculate the luminosity of the star 4th Measure the star's brightness 5th, Use the formula calculate the distance.
23. 5. A star begins its life with a mass of 5 MSun but ends its life as a white dwarf with a mass of 0.8 MSun. List the stages in the star's life during which it most likely lost some of the mass it started with. How did mass loss occur in each stage?
A very small fraction of a mass is lost while the main sequence is through the conversation of hydrogen into helium in later fusion cycle where the mass is converted to energy. As well through stellar winds. Mass is then lost during a red giant phase as well, during the time the outer layer lift off as a planetary nebula
23. 1. How does a white dwarf differ from a neutron star? How does each form? What keeps each from collapsing under its own weight?
A white dwarf has an electron degenerate object, while a neutron star is a neutron degenerate object. As a white dwarf has a larger radius, but less density. The collapse of a low mass star creates a white dwarf. The catastrophic collapse of the core of a massive star is then created into a neutron star. With the white dwarf it has a larger mass and as for the neutron star, it has a larger gravitational field. Once a white dwarf is stable enough it then forms and will continue to become a black dwarf. The neutron star slowley gathers more and more mass, then it could collapse again. White dwarf forms after the planetary nebula of a star. As for a neutron star, it forms before the rest of the star experience a type II supernova.
23. 24. If most stars become white dwarfs at the ends of their lives and the formation of white dwarfs is accompanied by the production of a planetary nebula, why are there more white dwarfs than planetary nebulae in the Galaxy?
A white dwarf is visible for a billion years or even more before it cools off and radiates, becoming feeble as to be undetectable. After a time on the order of 10,000 years or so, The gas shells then ejects the planetary nebula phase expanding and thins out to such an extent that then becomes observable, therefore there are many more whitedrawfs than planetary nebula
18. 16 There are fewer eclipsing binaries than spectroscopic binaries. Explain why
Eclipse only happen when the stars are lined up in a way that one star passes in front or behind . With spectroscopic binaries, they are only detected by the velocity that is associated with the orbital motion.
21. 4. Describe what happens when a star forms. Begin with a dense core of material in a molecular cloud and trace the evolution up to the time the newly formed star reaches the main sequence
First stage it involves the formation of a dense core from the clump of gas and dust that is presented in the molecular cloud. Second stage involves the overpowering of the pressure that is produced by the cold material of the dense core of the gravity pulling the falling gas. With this process the core of the star is starting to form into a true star. It happens before the proton undergoes into a fusion that then produces helium Developing into a protostar as it surrounds the center of it with particles that store additional materials from the molecular cloud. After a protostar is formed, a stellar wind breaks the additional particles forming a new star.
7-14 How do terrestrial and giant planets differ? List as many ways as you can think of
Giant planets Much larger than terrestrial planets Have hydrogen and helium glasses Jupiter, Saturn, Uranus, and Neptune are giant planets Greater number of moons compared to the terrestrial planets Higher magnetic fields The core of the giant planets are denser Terrestrial Planets Smaller than giant planets Made of rocks, minerals and metals Mercury, Venys, Earth and Mars are terrestrial planets Few moons Lower magnetic fields The core of terrestrial planets are less dense
20. 16. The terms H II and H2 are both pronounced "H two." What is the difference in meaning of those two terms? Can there be such a thing as H III?
HII represents the ionized hydrogen atom that is one electron but is removed, as in H2 it represents molecules that are made up of two hydrogen atoms. But no, it's not possible due to how there is only one proton and one electron
21. 15. What revisions to the theory of planet formation have astronomers had to make as a result of the discovery of exoplanets?
How the formation of planets is that it's more chaotic and less orderly. We now get to see how planets orbit at right angles to the plane of the other planets. Also we even see them move backwards. With the we have also learned that it is possible to have stable planets of two stars
17. 4. What elements are stars mostly made of? How do we know this?
Hydrogen and Helium. We know this because, by studying the light that they emit from. The atoms of each of the different elements makeup a star generates different colors.
16.20; TQ Explain what it means when we say that Earth's oceans are in hydrostatic equilibrium. Now suppose you are a scuba diver. Would you expect the pressure to increase or decrease as you dive below the surface to a depth of 200 feet? Why?
Hydrostatic equilibrium is maintained by the gravity of Earth which pulls the water downwards and the molecules of the water is being pushed out with the same force. If it was a scuba diver that is going 200 feet down, the pressure would increase having the weight of the water over me, as in my heartbeat maybe slower, and also the lungs wouldn't be able to catch oxygen well.
20. 3. Describe the characteristics of the various kinds of interstellar gas (HII regions, neutral hydrogen clouds, ultra-hot gas clouds, and molecular clouds).
Ionized Hydrogen Region; Near hot stars, after it's ionized hydrogen emits into a red color Neutral Hydrogen Cloud; Neutral state, doesn't emit in visible wavelength emits light with microwave wavelength. Ultra-Hot Gas Cloud; High Temp, Oxygen atoms ionized 5x emits into X-rays, The energy comes from massive star at the end of their lives Molecular Clouds; It produces visible absorption lines and radiation in radio and infrared wavelength, Also produces dust at the region and blocks the infrared rays from stars to keep the molecules from ionizing.
18. 14 Why do most known visual binaries have relatively long periods and most spectroscopic binaries have relatively short periods?
Isn't it because with visual binaries, the orbital is a bit larger, due to the axis of it. As with spectroscopic, it's short due to how the axis of it.
23. 14 What do astronomers think are the causes of longer-duration gamma-ray bursts and shorter-duration gamma-ray bursts?
It has a long duration that burst, lasting for about a few seconds. It then comes from a massive star with their own outer layer of hydrogen layers missing the explosion as a supernova. WIth short duration they are believed to be mergers of a stellar corpse either neutron stars or black holes. .
20. 5 Describe how the 21-cm line of hydrogen is formed. Why is this line such an important tool for understanding the interstellar medium?
It has the electromagnetic radiation that has a wavelength that it's equal to 21cm, and it's emitted during the change of energy levels of the electrons of neutral hydrogen atoms. It's important because it helps astronomers detect and understand the interstellar medium.
21. 20. Why were giant planets close to their stars for the first ones to be discovered? Why has the same technique has not been used yet to discover giant planets at the distance of Saturn?
It makes their star go back and forth around the center of the mass. With a big doppler shift, it can be observed in the radiation of the spectrum. If the brightness changes they can easily be found. The distance of Saturn from the Sun is 9.58 AU, taking about 29 years to complete one single rotation
16. 8; qt What do measurements of the number of neutrinos emitted by the Sun tell us about conditions deep in the solar interior?
It tells about the conditions that are deep in the solar interior giving us information about what's happening in the Sun's core. The number of the neutrions that come from the sun it tells us about the fission. The more numbers of neutrions tells us the rate of how it reacts more and if it's less than the neutrions may say that the Sun's fuel is low and it may explode anytime soon.
20. 8. What causes reddening of starlight? Explain how the reddish color of the Sun's disk at sunset is caused by the same process.
It the dust grains that are interacting with the starlight, causing it to redding by either absorbing and scattering the other colors
16. 1 ; RQ How do we know the age of the Sun?
It was measured by the other elements that were presented at the time of the formation of the Sun. In order to be able to determine the age of the sun, scientists estimated it the age to be about the same as Earth and the Moon. Soon they were able to gather rocks of the Moon, as they studied it, the age of the sun was then estimated to be around 4.5 billion years old.
18. 10. What would be the advantage of making parallax measurements from Pluto rather than from Earth? Would there be a disadvantage?
It would be faster to get information from earth due to how it takes one year compared to pluto since it takes about 200 years. The disadvantage would be that it takes a long time but you get more information and bigger baseline of it.
7. 15 Why are there so many craters on the Moon and so few on Earth?
It's because of the atmosphere that surrounds the earth. It's a thick atmosphere that helps avoid asteroids and other objects hit the surface of the earth, but instead ends up burnt in the atmosphere
20. 2 Why do nebulae near hot stars look red? Why do dust clouds near stars usually look blue?
It's because, its absorbing the radiation and also its due to the strong emission of the Balmer series of hydrogen atom that occurs, meaning it has low ionization energy, exciting the electrons to combine with the proton and moving it down to a lower energy level. With dust clouds, it looks blue due to how there is presence of dust grain in them that has been scattered from the light of the nearest star. Also, looks blue because of the size of it.
23. 20 Astronomers believe there are something like 100 million neutron stars in the Galaxy, yet we have only found about 2000 pulsars in the Milky Way. Give several reasons these numbers are so different. Explain each reason.
It's because, the lifetime of a pulsar is estimated to be about 10 million years. After the neutron star is no longer observable. Also with the energy beam radiation from a pulsar, sweeping over a circle in space,
17.2 rq Explain why color is a measure of a star's temperature.
It's depends on the wavelength.
20. 9. Why do molecules, including H2 and more complex organic molecules, only form inside dark clouds? Why don't they fill all interstellar space?
It's due to the accumulation of dust blocks out starlight stopping the ionization. It doesn't fill up space due to the number of dust grains that is only account for a fraction of the volume of interstellar space.
16. 2 ; QT Explain how we know that the Sun's energy is not supplied either by chemical burning, as in fires here on Earth, or by gravitational contraction (shrinking).
It's not supplied by the chemical burning if there was there would be residue and high temperatures. If the energy of the sun source was gravity contracting, the layers of the sun would fall inwards and cause the sun to shrink.
17. 25 Why can only a lower limit to the rate of stellar rotation be determined from line broadening rather than the actual rotation rate? (Refer to Figure 17.14.)
Its due to the direction of the observer.
17.1 What two factors determine how bright a star appears to be in the sky?
Luminosity and distance (apparent Brightness)
7. 24 TQ Again using Appendix F, which planet(s) might you expect not to have significant seasonal activity? Why?
Mercury (0.0) and Jupiter (3.1), due to how they are tilted away.
24. 2. If general relativity offers the best description of what happens in the presence of gravity, why do physicists still make use of Newton's equations in describing gravitational forces on Earth (when building a bridge, for example)?
Newton's equations are straightforward, therefore they were better used on the surface of the earth. Also there really is only a small difference between the two.
24. 8. What is a gravitational wave and why was it so hard to detect?
Ripples in the fabric of space-time creating a massive accelerating object.
17. 5. What did Annie Cannon contribute to the understanding of stellar spectra?
She kept 7 classes and their designations but changed the order from hottest to coldest
17. 17 Star X has lines of ionized helium in its spectrum, and star Y has bands of titanium oxide. Which is hotter? Why? The spectrum of star Z shows lines of ionized helium and also molecular bands of titanium oxide. What is strange about this spectrum? Can you suggest an explanation?
Star X is hotter. Due to how we can see the that ionized helium lines are stronger at high temp. As for Star Z the spectrum is strange because of the how the ionized helium and titanium oxides lines indicated both high and low temp at the same time.
23. 18. Suppose no stars more massive than about 2 MSun had ever formed. Would life as we know it have been able to develop? Why or why not?
Stars with masses that are less than two times the mass of the sun can produce elements that are only up to carbon and oxygen. More than a massive elements that are not produced, and some of these are more massive elements such as; phosphorus, calcium, silicon, and iron which are essentials to form life that is found on Earth.
15. 4; RQ Why do sunspots look dark?
Sunspots are the visible dark feature of the sun. They are known as cooler spots.
23. 4 How do the two types of supernovae discussed in this chapter differ? What kind of star gives rise to each type?
Supernova la are produced by white dwarf stars wither accretes enough mass to exceed e chandrasekhar limit and collapses into a neutron star. As for II supernova, they are caused by a collapsed massive star.
15. 16 TQ Suppose an (extremely hypothetical) elongated sunspot forms that extends from a latitude of 30° to a latitude of 40° along a fixed of longitude on the Sun. How will the appearance of that sunspot change as the Sun rotates? (Figure 15.17 should help you figure this out.)
The appearance of the sunspots will change as the sun rotates itself. Meaning that the sunspots will be moving faster, and may eventually break itself up into two or more sunspots.
18.32 You go out stargazing one night, and someone asks you how far away the brightest stars we see in the sky without a telescope. What would be a good, general response? (Use Appendix J for more information.)
The brightest stars that are actually visible in the night sky are mostly giants and supergiants. For example, in the Appendix J charts, the giants that are closer to earth would be Pollux, Capella and Arcturus, they are about 30-40 light years from Earth. The other stars that are that about a hundred light years away from earth would be, Rigel, Deneb, Betelgeuse and Antares. The brightest giants and supergiants in the sky can be around 600 light years away from earth.
15. 2 RQ Describe how energy makes its way from the nuclear core of the Sun to the atmosphere. Include the name of each layer and how energy moves through the layer.
The core, which is the center of the sun, It is made up of very heavy dense of gases and the temperature inside of the core is about 15 million k. With this temperature the hydrogen molecules combines itself with the helium molecules and produces the energy which then it travels through the core. It is also the hottest part of the sun Radiative zone, is the upper part of the core, it transports the energy the core. It goes through in very slowly since the density is high of matter. Next is Convective zone, it's the outermost part of the solar interior. It's about 200,0000 K deep, transporting the energy of the edge towards the sun's atmosphere d. The photosphere is the next layer where the light is visible that moves by the radiation. With this part you are able to see in photographs e. Chromosphere, is the middle layer and it is also pink. f.Corona is the outermost layer of the atmosphere, it is much higher than the photosphere.
21 12. Which types of planets are most easily detected by Doppler measurements? By transits?
The doppler effect measures the motion of the star that is caused by the pull of one or more planets that are around it. However, its only with those planets that have a very high mass and isn't far away from their stars. With small plantes, that are very far away, it is difficult to be able to detect using the doppler measurement, due to the radial velocity changes that are difficult to measure. Another way is being able to detect the brightness
17. 30. Suppose there are three stars in space, each moving at 100 km/s. Star A is moving across (i.e., perpendicular to) our line of sight, Star B is moving directly away from Earth, and Star C is moving away from Earth, but at a 30° angle to the line of sight. From which star will you observe the greatest Doppler shift? From which star will you observe the smallest Doppler shift?
The greatest doppler shift would be B due to how the wavelength shift is about 3.33x10^-4, Star A has no doppler shift as it only equals 0
15. 8; RQ Explain how the theory of the Sun's dynamo results in an average 22-year solar activity cycle. Include the location and mechanism for the dynamo.
The locations of the solar dynamo is between the Sun's convection zone and the radiation zone (below it) A dynamo is a machine that converts the kinetic energy into electricity. With the sun, it's the source of the kinetic energy that is churning of turbulent layers of ionized gas within the Sun's interior. It then generates the electrical currents, which it turns into generated magnetic fields.
18. 16. Figure 19.9 is the light curve for the prototype cepheid variable Delta Cephei. How does the luminosity of this star compared with that of the Sun?
The luminosity is much larger as the period is much shorter than the sun.
21. 21. Exoplanets in eccentric orbits experience large temperature swings during their orbits. Suppose you had to plan for a mission to such a planet. Based on Kepler's second law, does the planet spend more time closer or farther from the star? Explain.
The orbital velocity decreases with distance. Therefore the planet is less when it is far from the sun as it spends more time. With the temperature it has to spend more time closer to the star.
19. 1 Explain how parallax measurements can be used to determine distances to stars. Why can we not make accurate measurements of parallax beyond a certain distance?
The parallax measure is when a star is viewed from two different locations. Measuring the distance of the nearby stars. Which is D= 1/P. D is inversely proportional to the parallax. As for the 1 it would be equal to AU for arcseconds. P is the angle measured into seconds. The reason why we can't accurate the measurement is because it is very small and difficult to measure.
24. 16. If the Sun could suddenly collapse to a black hole, how would the period of Earth's revolution about it differ from what it is now?
The period wouldn't change at all. Far from the event horizon, a black holes gravitational field is in distinguished from any spherically symmetric object of the same mass.
21. 19. Suppose you wanted to observe a planet around another star with direct imaging. Would you try to observe in visible light or in the infrared? Why? Would the planet be easier to see if it were at 1 AU or 5 AU from its star?
The planet will be easier to see if it is further away from the parent star. If it's closer it would be even more likely to be lost in the glare of the parent star. The ratio of the brightness to the planet and the star is very small wavelength but it will be larger in the infrared than the visible light.
18.17 Which of the following can you determine about a star without knowing its distance, and which can you not determine: radial velocity, temperature, apparent brightness, or luminosity? Explain.
The radial velocity and temperature can be estimated by a spectrum. The apparent brightness can be directly observed. As with luminosity you must know the distance.
20. 14 If the red glow around Antares is indeed produced by reflection of the light from Antares by dust, what does its red appearance tell you about the likely temperature of Antares? Look up the spectral type of Antares in Appendix J. Was your estimate of the temperature about right? In most of the images in this chapter, a red glow is associated with ionized hydrogen. Would you expect to find an H II region around Antares? Explain your answer
The reddish color of the star is due to the oxide radiation presting itself around the star. Indicating that it has a lower temp and is cooler. The estimate was wrong that the colour that is associated with the ionized hydrogen. My estimation was wrong due to how the color is said to be associated with ionized hydrogen. Also if the star was in HII region the temp would be high, but since it's not found.
7.3 What does a planet need in order to retain an atmosphere? How does the atmosphere affect the surface of a planet and the ability of life to exist?
The role of our atmosphere is that it helps life exist. For life to exist there would need to be oxygen gas and also, water which is the result of change in the atmosphere on earth.
23. 30 How would the spectra of a type II supernova be different from a type Ia supernova? Hint: Consider the characteristics of the objects that are their source.
The spectrum of a type II supernova has hydrogen absorption lines, where the spectrum of type Ia supernovae is without hydrogen absorption lines, Ia has no hydrogen lines, no lines and has strong strong silicon lines. Another thing is that the spectrum of a type II supernova has hydrogen as its primary element and releases less energy where type Ia is the explosion of a dead star, the releases more energy that being said there is no hydrogen element that is presented in it due to this characteristic, Ia supernovae is used to determine the size of the universe.
16. 3; TQ What is the ultimate source of energy that makes the Sun shine?
The sun is a star, which is fuelled by the fusion that gets a reaction from hydrogen isotopes. The hydrogen atoms turns sold to shape the helium atoms, making a unique conditions that when they met. Radiating lots of energy. As the fusion react, the star is never ending unless it comes up short. After all the hydrogen atoms are spent, the helium atoms start to shape and form into heavier elements.
17. 13 If the star Sirius emits 23 times more energy than the Sun, why does the Sun appear brighter in the sky?
The sun is much closer to Earth than Sirius, so it's apparent brightness is greater than that of sirius.
7.6 Explain our ideas about why the terrestrial planets are rocky and have less gas than the giant planets.
The terrestrial planets and the gas planets are thought to be formed under different conditions. The inner planets are made of element that helps protect itself from the heat of the sun, as the gas that evaporates from it. With giant planets that are further away the gas that goes around the planet cores and stays there for the of the solar system.
15. 10: RQ What are the two sources of particles coming from the Sun that cause space weather? How are they different?
The two sources that are coming out of the sun that cause space weather are the coronal mass ejection and solar flares, both of the phenomenons create change in the electromagnetic field weakening it and destroying it.
20. 27 We can detect 21-cm emission from other galaxies as well as from our own Galaxy. However, 21-cm emission from our own Galaxy fills most of the sky, so we usually see both at once. How can we distinguish the extragalactic 21-cm emission from that arising in our own Galaxy? (Hint: Other galaxies are generally moving relative to the Milky Way.)
The way that we distinguish that 21cm is rising, is due to because of the energy that it has created.
15. 7; RQ What it the Zeeman effect and what does it tell us about the Sun?
The zeeman effect is the spitting lines of the magnetic field. It tells us about the sunspots.
15. 19; TQ How can the prominences, which are so big and 'float' in the corona, stay gravitationally attached to the Sun while flares can escape?
They must be traveling fast enough to speed to escape the gravitational pull of the sun
16. 22; TQ Suppose you are standing a few feet away from a bonfire on a cold fall evening. Your face begins to feel hot. What is the mechanism that transfers heat from the fire to your face? (Hint: Is the air between you and the fire hotter or cooler than your face?)
This would be because of the heat from the fire is radiated by all directions. With the air between the fire, my face wouldn't get heated due to how the fire isn't acting as a medium of transporting the heat.
17. 14. How would two stars of equal luminosity—one blue and the other red—appear in an image taken through a filter that passes mainly blue light? How would their appearance change in an image taken through a filter that transmits mainly red light?
Two stars have equal total luminosity, but the blue stars emits most of its energy due to shorter wavelengths. As for the red star, it emits more energy..
19.3 Explain how you would use the spectrum of a star to estimate its distance.
When both of the luminosity and the spectral class is known, the star positions itself on the H-R diagram and can be determined. Then we are able to calculate how far the star is by the difference between the luminosity and the apparent of the brightness.
24. 15. Which is likely to be more common in our Galaxy: white dwarfs or black holes? Why?
White dwarfs are more likely to be common. The number of the stars decrease with the increasing number of the mass, and only most of the massive stars are likely to complete three lives as black holes. There are many more stars of the masses appropriate for evolution to a white dwarf.
18.24 Approximately 9000 stars are bright enough to be seen without a telescope. Are any of these white dwarfs? Use the information given in this chapter to explain your reasoning.
With white dwarfs they have very low luminosities due to the emission of stored thermal energy, and has no fusion reaction in their core. Therefore, they aren't visible to the naked eye without using a telescope due to how they have low luminosity and high value of magnitude.
7. 28 TQ Would you expect as many impact craters per unit area on the surface of Venus as on the surface of Mars? Why or why not?
Yes because there is a thickness of atmosphere on venus then on mars. Meaning that more objects are protected by the atmosphere from landing on Venus and end up in its atmosphere. Venus is also almost twice the size of Mars.
24. 10 Suppose the amount of mass in a black hole doubles. Does the event horizon change? If so, how does it change?
Yes the event horizon is doubled and so does the mass as it doubles as well.
16. 9; qt Do neutrinos have mass? Describe how the answer to this question has changed over time and why.
Yes they do have mass. It was first proposed by Pauli a physicist that thought they were massless particles.
23. 16. Arrange the following stars in order of their evolution:
a. A star with no nuclear reactions going on in the core, which is made primarily of carbon and oxygen; an oldest star, it has no reactions that are taking place and is made up of carbon and oxygen which are heavier elements than helium and hydrogen. b. A star of uniform composition from center to surface; it contains hydrogen but has no nuclear reactions going on in the core.; Newly born star since it is compositions it is uniform containing hydrogen only and has no reactions that are taking place. c. A star that is fusing hydrogen to form helium in its core; Older than #2, Since the nucleus of hydrogen is fusing and forming helium d. A star that is fusing helium to carbon in the core and hydrogen to helium in a shell around the core.; Older than #3, since helium atoms are combing and forming carbon atoms which is heavier than helium e. A star that has no nuclear reactions going on in the core but is fusing hydrogen to form helium in a shell around the core.; No nuclear reactions that are taking place inside the core but the nuclear reactions are taking place on the surface, meaning it is older then #3, but younger than #1
19. 4. Which method would you use to obtain the distance to each of the following?
a. An asteroid crossing Earth's orbit; It can be measured by using the parallax measurement b. A star astronomers believe to be no more than 50 light-years from the Sun; Parallax measurement can be used to accurately calculate the distance of the stars even if they are 300 light years away. c. A tight group of stars in the Milky Way Galaxy that includes a significant number of variable stars; Because, it is a cluster of stars, as in Cepheids or RR Lyrae method it is used to calculate the distance of groups of stars in our own galaxy or another. d. A star that is not variable but for which you can obtain a clearly defined spectrum; It is spectral classification with H-R Diagram that is used to find the distance.
18. 11. Parallaxes are measured in fractions of an arcsecond. One arcsecond equals 1/60 arcmin; an arcminute is, in turn, 1/60th of a degree (°). To get some idea of how big 1° is, go outside at night and find the Big Dipper. The two pointer stars at the ends of the bowl are 5.5° apart. The two stars across the top of the bowl are 10° apart. (Ten degrees is also about the width of your fist when held at arm's length and projected against the sky.) Mizar, the second star from the end of the Big Dipper's handle, appears double. The fainter star, Alcor, is about 12 arcmin from Mizar. For comparison, the diameter of the full moon is about 30 arcmin. The belt of Orion is about 3° long. Keeping all this in mind, why did it take until 1838 to make parallax measurements for even the nearest stars?
arly observers didn't realize how far the stars were and how small the parallax angle could be. So the change in the positions of the stars were very small and wasn't able to be measured by the instruments that were available at that time. These parallax shifts were too small to be seen with the human eye and needed better types of instrument to be able to measure. Slowly, astronomers began able to build better and more capable equipment that were able to measure smaller angles. Until 1863, the first successful parallax measurement was carried out. WIth the advancement in technology more and more accuracy and sophisticated instrument came into existence making it possible to detect the very smallest parallax. Letting technology be more advanced instruments that led to a delay in the parallax measurement even for closer stars.
