Astronomy 151 Exam 2

The star Fawkes has a surface temperature T = 12,000 K. You compare the blackbody spectrum of Fawkes to the star Aragog and discover the peak wavelength of Aragog is 3.2 times larger (longer wavelength) than Fawkes. What is the surface temperature of Aragog? The star Aragog has a surface temperature T = ___________ K Give your answer to 1 decimal placeOnly enter the value of the temperature knowing the unit is Kelvin.

3,750

In this question, you need to determine how much more light large-sized telescope collects compared to a 1-meter diameter telescope. That is, you are determining how much brighter images will be when viewed with the larger telescope. Recall that the light-gathering power of a telescope is determined by the light-collecting area of the telescope. How much more light will a telescope with a diameter of 18.3 meters collect compared to a 1-meter diameter telescope. The 18.3 diameter telescope will have images _______________ times brighter than the 1-meter diameter telescope. Give your answer to two decimal places.

334.89

The star Fawkes has a surface temperature T = 12,000 K. You compare the blackbody spectrum of Fawkes to the star Sybill and discover the peak wavelength of Sybill is 2.5 times larger (longer wavelength) than Fawkes. What is the surface temperature of Sybill? The star Sybill has a surface temperature T = ___________ K Give your answer to 1 decimal placeOnly enter the value of the temperature knowing the unit is Kelvin.

4,800

Astronomers determine the age of the solar system to be ____ through radioactive isotope dating of _____ .

4.6 Gyr, meteorites

Use Wien's Law to determine the peak wavelength in nanometers (nm) of a star with a surface temperature, T = 6,148 K. Wien's Law for nm: λp=2900T⋅1000, where T is in Kelvin, and the peak wavelength will be in nm. The peak wavelength of a star with surface temperature T = 6,148 K is _____________ nm. Give your answer to 1 decimal place. Only input the numerical value for the wavelength knowing that the unit is nm

471.7

This week, we learned that the inherently bad angular resolution that radio telescopes suffer from can be overcome using technology. Specifically, astronomers can take advantage of the interference wave property to link an array of small radio telescopes together with cables and computers to create a "super telescope" called a radio interferometer. Consider the following radio interferometer and determine its effective diameter. The Dr. Lindsay Radio Array (DLRA) consists of 21 radio telescopes. Each radio telescope is a 25-meter telescope In its widest arrangement, the average distance between two neighboring telescopes is 750 meters. The longest distance between two of the telescopes in the array is 7.5 km. What is the effective diameter of the DLRA (in meters)?

7,500 meters

Greenhouse gases warm the surface of a planet beyond what is expected based on its distance from the Sun and how much light it absorbs/reflects because greenhouse gases...

Absorb some of the outgoing (outer space bound) infrared light emitted by the warm surface of the planet and reradiate it in all directions (half to space; half to Earth).

Planets form by the process of _____________________, where smaller object collect together to form larger objects.

Accretion

This term refers to the ability of a telescope (or eye, camera, etc.) to distinguish two objects as distinct points.

Angular Resolution

Earth's albedo is 0.3. What does this mean?

Earth reflects 30% of the sunlight that hits it

What are the characteristics of short-period comets? Choose all that apply: Note: I am not including a question about the long-period comets, but I expect you to know the characteristics for Exam 2.

Originate from the Kuiper Belt Have relatively low orbital inclinations Have orbital periods less than 200 years

Match the description of the telescope to the type of telescope

Uses a series of lenses to focus light and make an image Refracting Telescope Uses a series of mirrors and a lens to focus light and make an image Reflecting Telescope

These two bands within Earth's magnetosphere trap some of the incoming charged particles of the solar wind. There is an inner band and an outer band, which are both full of particle radiation that is harmful to life and electronics.

Van Allen Radiation Belts

An electron in a hydrogen atom moves from the n = 4 (3rd Excited state) to the n = 3 (2nd Excited State). The energy difference between the n = 4 and n = 3 electron energy levels is 0.7 eV. In this case, the electron in the atom ...

Will emit a photon with energy equal to 0.7 eV

What is the name of the technology astronomers use on a ground-based telescope to correct for the fact that turbulence in the atmosphere blur images?

adaptive optics

This small bodies region of the solar system is located between the orbits of Mars and Jupiter from about 2.1 - 3.5 AU. It contains hundreds of millions of small rocky objects, a significant number of which have a small amount of organic material (carbon-bearing molecules) incorporated into their composition.

asteroid belt

The angular size an object is blurred to due to turbulence in the atmosphere is quantified as the ______________________?

astronomical seeing

What term do astronomers use to describe how much light from outer space reaches the surface of the Earth? For example, a value of 0.8 for this quantity means that 80% of that wavelength of light does not reach the Earth's surface.

atmospheric opacity

When astronomers refer to the size of a telescope, what are they talking about? For example, the twin Gemini telescopes are each 8.1-meter telescopes. The 8.1 meters refers to the _______________ of the primary mirror (or objective lens)

Diameter

Question 13 on homework 7

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Question 2 EE week 8

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Question 4 on homework 6 1.5 telescopes

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Question 5 EE week 10

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Question 5 on homework 6 1.5 telescopes

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Question 9 on homework 6 1.5 telescopes

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Week 12 EE set question 10

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Homework 6: unit 1.5 telescopes question 19

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You determine the temperature of two stars, Star Galadriel and Star Arwen Star Arwen is 0.74 times the surface temperature of Star Galadriel. Note that means Arwen has a lower surface temperature than Galadriel. What is the ratio of radiative flux (energy per second per square meter) of Star Arwen compared to Star Galadriel. Star Arwen is releasing _______________ times the energy per second per square meter) that Star Galadriel is. Give your answer to 3 decimal places.

0.299

Which of of the following is a way that astronomers try to reduce or eliminate the problem of astronomical seeing? Choose all that apply:

1) Launch telescopes into outer space 2) Build telescopes on mountain tops 3) Use a technology called Adapative Optics to correct for atmospheric blurring

Which of the following choices are TRUE for radio telescopes Choose all that apply:

1) Radio telescopes have inherently bad angular resolution because radio waves have long wavelengths 2) Radio telescopes can operate on cloudy days 3) Radio telescopes can operate during the day and night. 4) Radio telescopes are great for observing the cold, molecular universe.

Which of the following are the correct consequences of Earth's tidal interactions with the Moon.

1) The Earth's rotational period is slowing down and the days are getting longer by about 2.3 ms/century 2) The Moon is spiraling outward getting farther from the Earth by about 4 cm/year

Use the drop down menus to correctly identify the described wave property. Diffraction describes how a wave will spread out as a result of passing through a narrow opening or spread out as it passes around a corner. Refraction describes how a wave, including light, will bend (change its direction of travel) as it passes from one medium to another.

1) diffraction 2) refraction

The two primary purposes of telescopes are to: 1) ________ by collecting as much light as possible to make dim astronomical objects appear brighter. 2) _________, or rather to make images as sharp as possible where two adjacent points can be distinguished from one another. Both of these goals are accomplished by ________

1) increase brightness 2) improve resolution 3) making telescopes larger

to find out which planets are more likely to have a magnetic field...

1) mass of 0.25 or 0.75 or more 2) ROTATIONAL period of less than 50 days

The equilibrium temperature is determined by balancing the energy going into Earth with the energy going out of the Earth. The energy in is determined by the distance from the Sun giving use the ______. of the light is absorbed by Earth of 1361 W/m2, and the albedo of the Earth (albedo = 0.3), which indicates that _________ of the light is absorbed by Earth. The energy out is the infrared light emitted by the Earth via thermal radiation. The actual temperature of the Earth is 33 K greater than this. The increase in the real temperature over the expected temperature is due to the ________

1) solar constant 2) 70% 3) greenhouse effect

Radio telescopes give astronomers an entirely different view of the universe than visible light telescopes. Radio waves are also one of the two spectral windows for Earth's atmosphere. This means that the atmosphere is transparent (or very nearly so) in that region of the electromagnetic spectrum, and we can build ground-based radio telescopes and observe the radio universe. A major problem with radio telescopes, however, is that they inherently have bad angular resolution due the the fact that radio waves have much longer wavelengths than visible light

1) spectral windows 2) longer

In general, radio, microwave, and infrared astronomy are best suited for observing ______ and ultraviolet, X-ray, and gamma ray astronomy are best suited for observing _________

1) the low, cool energy universe 2) the hot, high energy universe

The blackbody spectrum of Planet Charlie has a peak wavelength at 6 µm. Planet Genevra is TWO times hotter than Planet Charlie. What is the peak wavelength for Genevra's blackbody spectrum? Planet Genevra's blackbody spectrum peaks at ___________ µm Give you answer to 1 decimal place.Only put the numerical answer knowing the unit for wavelength is µm.

3

Which of the following describes the meaning of angular resolution?

The ability to distinguish two close together objects in the sky as distinct objects

In a Bohr Model of an atom, the number of protons determines what?

The chemical element the atom

Your goal in this question is recognize the qualities of an S-type Asteroid. Which of the following describe S-type asteroids? Choose the 3 that apply

-Higher percentage in the inner part of the Main Asteroid Belt -17% of all asteroids -Composition of silicate rocks and metal

What are the primary functions of a telescope? [Choose all that apply]

-Make sharp, detailed images (i.e, good angular resolution) -Make faint objects appear brighter

Question 10 EE week 8

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Question 10 on homework 6 1.5 telescopes

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Question 11 on homework 6 1.5 telescopes

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Question 11 on homework 7

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In this question, you need to determine how much more light a medium-sized telescope collects compared to a 1-meter diameter telescope. That is, you are determining how much brighter images will be when viewed with the larger telescope. Recall that the light-gathering power of a telescope is determined by the light-collecting area of the telescope. How much more light will a telescope with a diameter of 3.2 meters collect compared to a 1-meter diameter telescope. The 3.2 diameter telescope will have images _______________ times brighter than the 1-meter diameter telescope. Give your answer to two decimal places.

10.24

How much brighter will the images be using a telescope that is 11.2-meters in size compared to a 1-meter telescope? The larger telescope will make images that _____________________ brighter than a 1-meter telescope. [Round to 2 decimal places. If Canvas does the annoying thing where it adds a bunch of digits to your answer, just ignore it and still submit your answer]

125.44

The star Alastor has a surface temperature T = 6,400 K. You compare the blackbody spectrum of Alastor to the star Viktor and discover the peak wavelength of Viktor is 2.2 times smaller (shorter wavelength) than Alastor. What is the surface temperature of Viktor? The star Viktor has a surface temperature T = ___________ K Give your answer to 1 decimal placeOnly enter the value of the temperature knowing the unit is Kelvin.

14,080

You determine the temperature of two stars, Star Baggins and Star Took. Star Baggins is 3.45 times hotter than Star Took. What is the ratio of radiative flux (energy per second per square meter) of Star Baggins compared to Star Took. Star Baggins is releasing _______________ times the energy per second per square meter) that Star Took is. Give your answer to 1 decimal place.

141.7

Use Wien's Law to determine the peak wavelength in nanometers (nm) of a star with a surface temperature, T = 17,804 K. Wien's Law for nm: λp=2900T⋅1000, where T is in Kelvin, and the peak wavelength will be in nm. The peak wavelength of a star with surface temperature T = 17,804 K is _____________ nm. Give your answer to 1 decimal place. Only input the numerical value for the wavelength knowing that the unit is nm

162.9

You determine the temperature of two stars, Star Mithrandir and Star Saruman. Star Mithrandir is 11.65 times hotter than Star Saruman. What is the ratio of radiative flux (energy per second per square meter) of Star Mithrandir compared to Star Saruman. Star Mithrandir is releasing _______________ times the energy per second per square meter) that Star Saruman is. Give your answer to 1 decimal place.

18,420.6

Which of the following is TRUE about an electron in the Bohr Model of the Atom?

The electron is restricted to certain energies described by electron energy levels

Every element has its own unique set of emission and absorption lines AND the wavelengths of the emission and absorption lines are the same.

True

This type of asteroid is more common in the outer regions of the Asteroid Belt. They account for 75% of all asteroids, and have rocky-metallic compositions with a significant amount of carbon-bearing molecules on them. The carbon makes them very dark, and hence have albedos around 0.03 - 0.09.

C-type asteroids

Which of the following can you determine about celestial objects that have either emission or absorption spectra through analyzing its spectrum and the details of the spectral lines? Choose all that apply

Chemical Composition Radial Motion Magnetic Field Strength Temperature Pressure & Density Rotation State (How it is rotating)

By identifying the presence of spectral lines (either emission or absorption lines), and associating them with the wavelength they appear at, astronomers can determine...

Chemical composition

What part of the modern solar system formation theory explains the current compositional gradient we observe in the solar system?

Condensation theory

Do you know your Kirchhoff's Laws? Match the type of spectrum to the physical scenario where it is observed.

Continuous Spectrum Observed when looking at the spectrum of a blackbody Emission Spectrum Observed when looking at a hot, thin (very low density) gas Absorption Spectrum Observed when looking at the light of a blackbody after it passes through a cool, thin (very low density) cloud of gas

What kind of planet is Neptune?

Ice Giant

These worlds are composed mostly of ices (methane, water, CO2, etc.) with a significant mass of hydrogen and helium gas (about 1 - 2 Earth masses worth)

Ice giants

Use Wien's Law to determine the peak wavelength in microns (µm, or formally, micrometers) of a star with a surface temperature, T = 3,177 K. Wien's Law for µm: λp=2900T, where T is in Kelvin, and the peak wavelength will be in µm. The peak wavelength of a star with surface temperature T = 3,177 K is _____________ µm. Give your answer to 3 decimal places. Only input the numerical value for the wavelength knowing that the unit is µm

Idk, but not 912.811

Which of the choices is evidence that the gas giant planets in our solar system migrated, and thus cleared out the remaining planetesimals and protoplanets, during the early planetary formation stages of the solar system?

The craters on the Moon and Mercury indicating a time of Late Heavy Bombardment about 3.9 Gya

Operating at a wavelength, λ = 500 nm = 0.5 µm, the 2.4-meter Hubble Space Telescope has an angular resolution of AngularResolution=0.25⋅(0.552.4) = 0.573 arcsec Hubble looks at a pair of binary stars (two stars next to one another and often in orbit around one another) that have a angular separation of 0.350 arcsec. In this case, what does Hubble see?

It sees a single blur of light

What major terrain/large-scale surface feature on the Moon is characterized as large, roughly circular smooth plains that are darker in color and lower in altitude than the rest of the lunar surface?

Lunar Maria

Match the description to the extrasolar planet detection technique it describes.

Measures the reflex motion of a star in response to an orbiting planet using the Doppler Effect Radial Velocity Method Measures the dip in light a planet causes when it passes in front of its host star from our line of sight. Transit Method

Where is the Kuiper Belt located?

Past the orbit of Neptune from 30 - 55 AU

Which of the following photons has the highest energy? Photon A: Wavelength = 500.0 nm Photon B: Wavelength = 656.3 nm Photon C: Wavelength = 88.0 nm Photon D: Wavelength = 1,900 nm Photon E: Wavelength = 1 meter

Photon C has the highest energy

The process by which a planet will layer itself by density, such that the denser materials will settle to the center of a planet while the less dense materials will rise toward the surface, is called?

Planetary Differentiation

What do astronomers call a system of radio telescopes that are linked together using electronics and computers to create a "super telescope" that has a very large effective diameter, and therefore a much improved angular resolution compared with any radio telescope operating by itself.

Radio Interferometer

What is thought to be the primary contributor to the heat (i.e., provided the largest amount) that was needed to melt the early planets?

Radioactivity of short half-life radioactive isotopes

This type of asteroid is more common in the inner regions of the Asteroid Belt. They account for 17% of all asteroids, and have rocky-metallic compositions. They have no carbon-bearing molecules or ices found on them.

S-type asteroids

What planet is the 6th farthest from the Sun?

Saturn

What do geophysicists use to determine the interior structure of the Earth?

Seismic waves

Seismic S-waves can travel through which of the following? Choose all that apply.

Solids

What is the branch science that studies the interaction of light and matter through breaking light out into its component wavelengths called?

Spectroscopy

What is the name for the tools astronomers use that collect as much light as possible from an astronomical source and focuses it down to a narrow beam to form an image?

Telescope

What event does the spike in cratering rates around 3.9 Gya (Giga-years ago; 3.9 billion years ago) reveal? This increase in cratering rates is preserved in the cratering history of the Moon and Mercury.

The Late Heavy Bombardment

The same side of the Moon always faces the Earth. We call the side that we see the lunar near-side, and we had never observed the lunar far-side until the space era when we finally sent a spacecraft around the Moon to see the side that faces away from us. Why do we always see the same side of the Moon?

The Moon rotates exactly once per orbit around the Earth

What do planetary scientists call the atmosphere that is formed early in the evolution of the planet by volcanic outgassing? This gives this primordial atmosphere an expected composition of mostly CO2 gas with some water vapor, nitrogen compounds, SO2, and other volcanic gases?

The Secondary Atmosphere

What do astronomers call the flattened into a disk-shape, rapidly rotating disk with the proto-sun at its core, out of which, the planets and small bodies of the solar system formed?

The Solar Nebula

Using a large ground-based telescope with a diffraction-limited angular resolution of 0.08 arcsec, you observe a star. It is a calm, clear night with astronomical seeing of 0.35 arcsec. The star is the same size as our Sun, and given its distance away from Earth, you can calculate that is should have a real angular size of 0.001 arcsec. What do you see with your telescope?

The star as a circular dot with a width of 0.35 arcsec

You observe the spectrum of a star using a telescope equipped with a spectrometer. You carefully measure the position of its hydrogen alpha line in absorption to be at 657.2 nm. You know that the rest wavelength for a hydrogen alpha photon is 656.3 nm. From this information you can correctly conclude:

The star is moving radially away from the Earth

What layer of Earth's atmosphere does convection occur in?

Troposphere

Complete the following narrative about how Earth's atmosphere evolved from a secondary atmosphere to the current atmosphere. Earth's secondary atmosphere was made of volcanic gasses including a lot of carbon dioxide (CO2), some sulfur dioxide (SO2), nitrogen compounds (e.g., NH3, NO2, NO, etc.), argon (Ar), and water vapor (H2O). Earth's secondary atmosphere also had upwards of 80 times the mass of our current atmosphere. The carbon dioxide was removed from the atmosphere as the atmosphere cooled and the water vapor condensed to form our oceans. The nitrogen was slowly built up over time through the photodissociation of nitrogen compounds in the atmosphere from the Sun's ultraviolet light. The oxygen was generated approximately 2.5 billion years ago through the evolution of photosynthetic life. This left the atmosphere being much thinner than the secondary atmosphere with the current atmospheric composition we observe today.

carbon dioxide, nitrogen, oxygen

These worlds are composed almost entirely of hydrogen and helium gas and are by far the two most massive objects in the Solar System.

gas giant planets

Planet Gellert is 12.5 times hotter than Planet Morfin. An examination of Planet Morfin's blackbody spectrum reveals that it peaks at 19.2 µm. If we were measure Planet Gellert's blackbody spectrum, it would peak at what wavelength? Planet Gellert's blackbody spectrum peaks at ___________ µm Give you answer to 2 decimal places.Only put the numerical answer knowing the unit for wavelength is µm.

idk, but you DON'T MULTIPLY (so not 240)

Planet Padma is 3.2 times hotter than Planet Pavarti. An examination of Planet Pavarti's blackbody spectrum reveals that it peaks at 9.4 µm. If we were measure Planet Padma's blackbody spectrum, it would peak at what wavelength? Planet Padma's blackbody spectrum peaks at ___________ µm Give you answer to 2 decimal places.Only put the numerical answer knowing the unit for wavelength is µm.

idk, but you DON'T MULTIPLY (so not 30.08)

Sharing an orbit with the largest planet of the solar system, these asteroids are located at 5.2 AU.

jupiter trojan asteroids

This region in the solar system is donut-shaped region past the orbit of Neptune. This region is estimated to have hundreds of thousands of small rocky-icy objects larger than 100 km in diameter, and it is the source for the short-period comets.

kuiper belt

Located from 2.1 AU to 3.5 AU, between Mars and Jupiter. Contains upwards of 100s of millions of asteroids.

main asteroid belts

The terrestrial planet forming region of the solar nebula had estimated temperatures greater than 600 K for the entirety of the region Mercury, Venus, Earth, and Mars formed in. Use the given condensation sequence to determine what solid grains could form in the terrestrial planet forming region. Condensation Sequence of Solid Grains Material & Condensation Temperature: Metal 1700 K; Silicate Rocks 1200 K; Organics 500 K; Water-ice 273 K; Carbon Dioxide Ice 200 K Choose all that apply

metal, rock

Located near 1.0 AU, these asteroids are only temporarily in this region (10 to 100s million of years) before they collide with the Sun or one of the planets (including Earth).

near earth asteroids

Complete the table for the composition of Earth's Atmosphere Atmospheric GasPercent of Atmosphere (by Volume): nitrogen ___; oxygen ___; argon 0.9%

nitrogen: 78% oxygen: 21%

This small bodies region of the solar system is a theoretically predicted spherical shell of small icy bodies at the limits of our Solar System extending from about 1,000 to 100,000 AU. It's existence is evidenced by the vast majority of long-period comets having semi-major axes of about 50,000 AU.

oort cloud

The presence of Hot Jupiter planets orbiting very near to their host stars (usually closer than Mercury orbits our Sun), provides evidence that ________________________ is common in planetary system formation.

planetary migration

Radio telescopes are what kind of telescope design?

reflecting telescopes

These are worlds made primarily of rock and metal located in the inner Solar System.

terrestrial planets

to find which planets are more likely to have an atmosphere:

the expected temperature is LESS than the real temperature

Identifies a periodic dip in the brightness of the host star when an planet passes in front of the star.

transit method