GIZMOS Student Exploration: Big Bang Theory – Hubble’s Law 2024 (answered), Exams of Nursing

Download GIZMOS Student Exploration: Big Bang Theory – Hubble’s Law 2024 (answered) and more Exams Nursing in PDF only on Docsity! Explain: If the light that you are seeing is brighter that means that they are closer to you than the other motorcycle. The motorcycle covers more distance than the bicycle. Name: Shelby Fisher Date: 10/07/2021 STUDENT EXPLORATION: BIG BANG THEORY – HUBBLE’S LAW DIRECTIONS: FOLLOW THE INSTRUCTIONS TO GO THROUGH THE SIMULATION. RESPOND TO THE QUESTIONS AND PROMPTS IN THE ORANGE BOXES. Vocabulary: absolute brightness, absorption spectrum, apparent brightness, Big Bang theory, blueshift, Cepheid variable, Doppler shift, Hubble constant, Hubble’s law, luminosity, megaparsec, period, redshift, spectrograph Prior Knowledge Questions (Do these BEFORE using the Gizmo.) Standing by the side of a lonely highway at night, you see two motorcycle headlights, one in each direction. The headlight on your left appears brighter than the one on your right. 1. If the headlights are equally bright, which motorcycle is closer? 2. Suppose the dim-looking headlight on the right is actually a small light on the front of a bicycle. What can you conclude about the distance of the motorcycle and bicycle? GIZMO WARM-UP In 1912, an astronomer named Henrietta Swan Leavitt studied a class of stars called Cepheid variables. These stars change from bright to dim to bright again. Her discoveries led to a method of measuring distances to other galaxies and eventually helped to support the Big Bang theory of the origin of the universe. In the Big Bang Theory – Hubble’s Law Gizmo, select Region A. Look at the image of the Andromeda Galaxy, a galaxy relatively close to our own Milky Way galaxy. The one on the left A. Which star reaches a greater apparent brightness? A-091 B. Which star takes longer to pulse? A-091 The brighter the star, the more time it takes to pulse. 1. Locate the two Cepheid variables, the stars that change in brightness over time. Star A-091 is the yellow star, and A-171 is the white star. 2. Because both stars are in the same galaxy, they are about the same distance from Earth. Based on what you see, how is the brightness of the star related to how quickly it pulses? D-819, C-197, A-091 colors when it passes through an instrument called a spectrograph. The result is a pattern of colors and black bars called an absorption spectrum. The bars represent wavelengths of light that are absorbed in the star’s atmosphere. Each star’s unique spectrum depends on the temperature and composition of its atmosphere. Look at the spectrum of A-091. ✏ Sketch the lines of its stellar spectrum in the diagram below. Click to select Edit to use the drawing tool. 4. Record : Click Done. Select the other Cepheid variable star in the Andromeda Galaxy (A-171). Determine and record the period, mean brightness, and spectrum of this star. Then, click Return to map and select Region B. There are a total of ten Cepheids hidden in the nine regions of the Gizmo. Record the period, mean brightness, and spectrum of all ten stars both in the Gizmo data table and on your own data table. 5. Compare : By comparing Cepheid variables that were all about the same distance away, Henrietta Leavitt discovered that larger, more luminous Cepheids had longer periods. Look at the periods of the ten stars in your data table. A. Based on the periods of the stars, which three stars are the most luminous? B. Find two stars with similar periods, and therefore similar size. List these stars, their periods, and their mean brightness below. Star: Star: A-171 Period: Period: 3.0 Mean brightness: 92.66 B-618 4.1 2499 B-618 appears to be farther away, because the mean brightness is much larger than A- 171 Get the Gizmo ready: Select the DISTANCE tab. Check that Luminosity vs. Period is selected. Activity B: Luminosity and distance Mean brightness: C. Compare the apparent brightness of these two stars. Which star do you think is farther away? Explain. B-618 luminosity ratio: 12.81 C-197 luminosity ratio: 100.22 Introduction: Henrietta Leavitt observed Cepheids inside the Small Magellanic Cloud, a star cluster just outside the Milky Way. All of these stars are about the same distance away. Leavitt found that the most luminous Cepheids had the longest periods. By relating each Cepheid’s luminosity to its period, Leavitt discovered a way to find the luminosity of a Cepheid in any galaxy. By comparing the apparent brightness of a Cepheid variable to its known luminosity, the distance to any Cepheid (and its host galaxy) could then be determined. GOAL: FIND THE MEAN LUMINOSITY AND DISTANCE OF CEPHEID STARS. 1. Collect data : On the DISTANCE tab, check that the Luminosity vs. Period graph is selected. Notice that as the period of a Cepheid variable increases, so does its luminosity. A luminosity of 2,000 Suns means that the star is 2,000 times brighter than the Sun. A. Based on the graph, what is the approximate mean luminosity of a Cepheid variable star with a period of 5 days? 2102 10 days? 3762 B. Turn on Show draggable point. Move the point so that its x–coordinate is equal to the period of star A-091. What is the mean luminosity of this star? 4338 Record this value in the data table of the Gizmo and on your own data table. C. Use the draggable point to find the mean luminosity of the other stars. If necessary, use the +/- zoom controls to zoom in or out on the graph. Record your results in the Gizmo and in your own data table. 2. Calculate : The distance to a star can be found by comparing its luminosity to its apparent brightness. A star that is far away will be very dim compared to its luminosity, and the ratio of its luminosity to apparent brightness will be greater than for a nearby star. A. Stars B-618 and C-197 have about the same mean brightness. Calculate the “luminosity ratio” of each by dividing its mean luminosity by its mean brightness. Get the Gizmo ready: Select the SPECTRA tab. On the DATA pane, click the right arrow so the Redshift (z) column is visible. Activity C: Redshift Introduction: Have you ever listened to the siren of an ambulance? As the ambulance passes by, the pitch of its siren gets lower. This occurs because of the Doppler shift. Sound waves are compressed as the ambulance approaches, causing the pitch to be higher. As the ambulance drives away, the sound waves are spread apart, causing the pitch to be lower. A similar effect occurs if a star or galaxy is moving relative to Earth. When a star approaches Earth, the light waves it emits are compressed, causing its light to be shifted toward the blue end of the spectrum. This is They are shifting right A. What is the wavelength of the line on the reference spectrum? B. What is the wavelength of the line on star C-197’s spectrum? Shifted to the red called blueshift. When a star moves away from Earth, its light is shifted toward the red end of the spectrum, a phenomenon called redshift. GOAL: MEASURE AND INTERPRET THE REDSHIFT OF CEPHEID VARIABLE STARS. 1. Check : In the bottom half of the Spectra tab, you should see 10 stellar spectra. If you are missing any, go back to the Stars tab, find the missing star, and record its spectrum. 2. Observe : You can measure redshift by comparing the wavelength of a black absorption line on the star’s spectrum with an equivalent line on the reference spectrum. Drag the spectrum for star C-197 into the top part of the Spectra tab. Do you notice any difference in the locations of the absorption lines in the reference spectrum and the spectrum for star C-197? Describe. 3. Measure : Drag the probes to equivalent lines in each spectrum. Then, zoom in on the graph by clicking +. Adjust the probes so they are exactly on each absorption line. C. Has the spectral line of star C-197 been shifted to the right (redshift) or to the left (blueshift)? D. Is the galaxy that contains star C-197 moving toward our galaxy (the Milky Way) or away from our 487.2 486.1 Moving away 0.0025What is the redshift of star C-197? galaxy? Explain. 4. Calculate : Redshift (z) is calculated by dividing the wavelength of the observed absorption line (λobs) by the wavelength of the equivalent reference line (λref), and subtracting 1. (If the redshift is negative, the light is blueshifted.) z = Check your answer by turning on the Redshift calculator. 5. Record : Repeat the procedure to measure the redshift of each star. Record your answers in the Gizmo and on your data sheet. If the stars like A-091 and A-171 are basically on top of each other on the graph you can tell which the closest ones are because they are in the andromeda galaxy. The others move up parsecs/light years away, which is a really big difference from us. A. What pattern do you see? You see an incline on the graph, and then when you hit D- 819 it declines. B. What does this pattern indicate about how quickly other galaxies are traveling away from our own galaxy? Explain your reasoning. 1. Graph : At this point, you should have distance and redshift data for all 10 stars in the Gizmo. If not, go back and fill in any missing data. Below the Redshift vs. Distance graph, you will see a table with the star names and draggable dots. Drag each dot to the graph to create a scatterplot of redshift vs. distance. ✏ Sketch your resulting graph in the grid to the right or click to select EDIT to use the drawing tool. 2. Interpret : The greater the redshift of a star, the faster it is moving away from our galaxy. Select Velocity vs. distance to see the same data graphed in terms of velocity. The more our universe expands the more spread out galaxies are going to be. So by having G-958 being farther away, if the universe expanded more and more, it would be farther away than it was before. away? If a galaxy is farther away, it appears to be moving faster. The blue and orange dots from the Andromeda galaxy are at -300 km/s which is slow while G-958 is 1593.0 km/s. There is a big difference between the two. This pattern is called Hubble’s law. B. Turn on Show trendline. What is the slope of this trendline?75.5 km/s/Mpc This value, known as the Hubble constant, describes how recessional velocity is related to distance. The modern value of this constant is about 70 km/s/Mpc. A. In general, how does the distance to a galaxy relate to how quickly it appears to be moving C. How does Hubble’s law provide evidence that the universe is expanding? (Hint: Imagine our galaxy was a dot on a balloon that was covered by other dots. As the balloon expanded, which dots would move away from our dot most quickly?) Just like Hubble with his scatterplot, you can also tell from my graphs that the universe is expanding. The distance between the stars (Mpc) gets bigger and bigger whenever the universe expands. The biggest distance is from 0.78 to 21.9 Mpc. And just like a point on a balloon, when time progresses those distances will increase and separate. Date: 10/12/2021Shelby FisherName: 3. Draw conclusions : In 1927, a little- known Belgian priest named Georges Lemaître was the first to propose an expanding universe, based on Einstein’s theory of general relativity. Two years later, Edwin Hubble published a scatterplot of recessional velocity vs. galactic distance, shown at right. This was the first observational evidence to support the hypothesis that grew into the Big Bang theory. Describe how the evidence you have gathered in this Gizmo demonstrates that the universe is expanding and helps to confirm the Big Bang theory. BIG BANG THEORY – HUBBLE’S LAW: STUDENT DATA TABLE Instructions: As you record data in the Gizmo data table, record the same data here as well. Turn in this table with the rest of the Student Exploration sheet. Luminosity