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Student Exploration: Big Bang Theory – Hubble’s Law Latest Update 2023 Guaranteed Success., Exams of Geography

Saint Francis Medical Center College of NursingGeography

Student Exploration: Big Bang Theory – Hubble’s Law Latest Update 2023 Guaranteed Success.A+

Typology: Exams

2022/2023

Available from 11/30/2023

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Student Exploration: Big Bang Theory – Hubble’s Law Latest
Update 2023 Guaranteed Success.A+
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? The one on the left side
Explain: If it is brighter than that means its going to be closer because the light particles
are traveling less and there is more.
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?
If I know the light source is smaller, then the bicycle is closer than it is shown.
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.
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.
A. Which star reaches a greater apparent brightness? Star A-091 has a greater
apparent brightness
B. Which star takes longer to pulse? Star A-091 takes longer to pulse than the others.
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?
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Student Exploration: Big Bang Theory – Hubble’s Law Latest

Update 2023 Guaranteed Success.A+

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? The one on the left side Explain: If it is brighter than that means its going to be closer because the light particles are traveling less and there is more.
  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? If I know the light source is smaller, then the bicycle is closer than it is shown. 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.
  3. 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. A. Which star reaches a greater apparent brightness? Star A-091 has a greater apparent brightness B. Which star takes longer to pulse? Star A-091 takes longer to pulse than the others.
  4. 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?

The more a star pulses the dimmer the star is.

worksheet. (Activity A continued on next page)

star is farther away the more it is dimmer. Even if they had the same brightness, the star further away from us is going to be appear dimmer.

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? 2,000 10 days? 3, 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. B-618 luminosity ratio: 12.8 C-197 luminosity ratio: 98. Get the Gizmo ready: Select the DISTANCE tab. Check that Luminosity vs. Period is selected. Activity B: Luminosity and distance

Activity B (continued from previous page)

  1. Infer: Below the data table, click the right arrow once. You should now see a column labeled Luminosity/brightness. The ratio of each star’s luminosity to its brightness has been calculated for you. Based on these ratios, which stars are closest, and which stars are farthest away? Closest: A-091, A-171, B-618, Farthest: C-197, D-819, E-429, F-520. G-958, H-716, I- 450 Explain: The luminosity/brightness ratio for the closer stars is less than the mean brightness, meaning its closer to us.
  2. Record: On the DISTANCE tab, select Distance vs. Luminosity Ratio. This graph allows you to estimate the distance of each star, measured in megaparsecs (Mpc), based on its luminosity ratio. A. Based on the graph, how does the ratio of a star’s luminosity to its apparent brightness relate to its distance? When a stars luminosity to its apparent brightness is low, the less distance there is. The more its luminosity/brightness, the more further away it is from Earth. B. Use the draggable point to find each star’s distance. Record in the Gizmo data table and on your own data table.
  3. Compare: In the left column at right, list the stars in order of mean apparent brightness, from brightest to dimmest. In the right column, list the actual distances of these stars. Suppose you estimated the distances of stars based only on their apparent brightness. Based on this group of stars, would this method work well? Explain. It is not accurate in some places, but overall the brightness does correlate to the distance in most of the chart. Maybe if I tried a different group of stars it would work better. Apparent brightness Distance A-091 0. A-171 0. B-618 3. C-197 9. F-520 7. H-716 12. D-819 22. E-429 12. G-958 18. I-450 15.

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 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. I see a slight difference in locations and color of the absorption lines
  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. A. What is the wavelength of the line on the reference spectrum? 486. B. What is the wavelength of the line on star C-197’s spectrum? 487. C. Has the spectral line of star C-197 been shifted to the right (redshift) or to the left (blueshift)? It has been red shifted to the right D. Is the galaxy that contains star C-197 moving toward our galaxy (the 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

Activity C (continued from previous page)

  1. Calculate: Redshift ( z ) is calculated by dividing the wavelength of the observed absorption line ( λ obs) by the wavelength of the equivalent reference line ( λ ref), and subtracting 1. (If the redshift is negative, the light is blueshifted.) z =

obs

ref

What is the redshift of star C-197? 0. Check your answer by turning on the Redshift calculator.

  1. Record: Repeat the procedure to measure the redshift of each star. Record your answers in the Gizmo and on your data sheet. Which star has the greatest redshift? Star I-450 Greatest blueshift? Star A-
  2. Infer: The Big Bang theory states that the universe began at a single point, and that the universe is still expanding today. A. Are most stars redshifted or blueshifted? Most stars are redshifted. B. What does this tell you about the galaxies that contain these stars? It tells us that the universe is expanding and that the galaxies that are close are blue shifted, while the rest are redshifted and spread apart. C. How does this relate to the theory that the universe is expanding? Because most stars are redshifted, this means that the universe is expanding at a rapid pace because a majority of the galaxies & stars are far away from us.
  3. Analyze: Compare the redshifts you measured to the distances to the various stars. A. In general, what do you observe about the redshifts of stars that are relatively close to Earth? Redshifts that are closer to earth move away at a slower pace. B. What do you notice about the redshifts of stars that are very far away? They move at a faster pace compared to the ones that are closer to earth.

(Activity D continued on next page)

movement connect, making it known that the farther away a star is the faster it is moving. This does prove the big bang theory, because it shows that the universe is still affected and expanding by the second. Technically the big bang theory is still happening.

Name: Date:

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. Star Period (Days) Mean brightness Mean luminosity* Luminosity Brightness Distance (Mpc) Redshift (** z ) A-091 12.3 7004 4338 0.619 0.78 -0. A-171 4.0 2499 1526 0.611 0.78 -0. B-618 3.0 92.66 1187 12.8 3.58 0. C-197 25.0 87.9 8640 98.3 9.91 0. D-819 27.2 19.43 9386 483 22.0 0. E-429 5.8 14.32 2136 149 12.2 0. F-520 9.3 52.16 3321 63.7 7.98 0. G-958 11.8 12.94 4168 322 18.0 0. H-716 11.0 24.85 3897 157 12.5 0. I-450 7.0 10.84 2542 235 15.3 0. *Mean brightness is the mean apparent brightness of the Cepheid variable star. This is the ratio of the observed mean brightness of the star to the brightness of the Sun when viewed from a distance of one megaparsec (1 Mpc). **Mean luminosity is the ratio of the luminosity of the Cepheid variable star to the luminosity of the Sun.