Astro 1 Exam 2 PSU

How many Jupiters would fit across Sun end-to end?

10

How many earths would fit across Jupiter?

11

How many earths would fit across the sun end to end?

110

A star with a known exoplanet around it has a mass of 1.3 solar masses. If the period of the planet is 3.6 years, how far does the planet orbit from the star? Give your answer in AU.

2.56 AU

Angular Resolution of a telescope (how each depends on the size of telescope and/or wavelength of light observed)

ability to see fine detail, example: observe two objects which appear close together in the sky in two distinct objects. Small resolution = good. larger the telescope = better the angular resolution. Blue = shorter wavelength, better resolution. red = long wavelength, worse resolution

how much mass is in all the planets of the solar system when compared to the sun?

about 0.1%

What type of spectrum does the sun produce?

absorption

Thermal (Blackbody) Radiation

an opaque object that has a temperature and produces radiation in the form of a continuous spectrum

Titan is roughly the same size as mercury, titan (saturns moon) as atmosphere while mercury does not. This is because titan is

colder

all planets orbit the sun ________ and nearly in the same _____

counterclockwise, plane

Emission Line:

created by a hot diffuse cloud of gas Photons are emitted from an atom when an electron moves from a higher energy level to a lower energy level. (all black with colorful lines)

Absorption:

created by a hot solid (liquid or gas) seen through a diffuse cloud or gas. photons can be absorbed by an atom when an electron moves from a lower energy level to a higher energy level (all colorful with black lines)

What type of spectrum does the sun show?

dark line absorption spectra

Doppler Effect - Moving Objects

different observers will observe different wavelengths - approaching side: observer will measure a shorter wavelength than emitted - receding side: observer will measure a longer wavelength

What type of spectrum does a hot gas in a nebula produce?

emission

Light from an extremely hot star ionizes the hydrogen gas around it. The electrons recombine. What type of spectrum do you see when you look at the gas?

emission line spectrum

meterorides

fragments of rocky material

Asteroids

fragments of rocky material. very old. between mars and jupiter. not like planets.

which planets are generally the easiest to find using the radial velocity method?

high mass planets close to their stars

emission

higher -> lower level (arrow going towards nucleus)

comets

icy, but have some rocky material

def of a Planet (What are the three criteria that a planet must meet?)

"A moderately large object that orbits a star and shines primarily by reflecting light from its star. an object can be considered a planet only if: - 1) it orbits a star - 2) is large enough for its own gravity to make it round - 3) has cleared most objects from its original path. (dominates its orbital region)-not pluto

How did the moon form?

(Large Impact) Impact theory. large mars-size objects hit the earth while the earth was still young and molten. most pieces of the splattered earth (mostly from the mantle) recombine into moon forming a stable orbit.

How can we detect exoplanets?

1. gravitational tugs: radial velocity and astrometric technique 2. transits and eclipses 3. direct detection 4. microlensing

The solar system is ______ years old

4.5 billion

Which shows ionization (an electron being ejected from the atom)?

A (arrow is on the outermost ring and going outward)

Which of the following setups would result in the best angular resolution?

A large telescope looking at blue light

16. Star A has a temperature of 4,000 K, and Star B 8,000 K. Which of the following is true about these two stars? A. Star A will give off less total light than star B. B. Star A will give off more yellow light than Star B. C. Star A will give off more red light than Star B. D. Star A will give off more total light than Star B. E. Star A will give off more blue light than Star B.

A. Star A will give off less total light than star B.

17. If we raise the temperature of an object from 2,000 K to 3,000 K, which of the following is TRUE about its blackbody curve? A. The area under the curve increases and the peak shifts to shorter wavelengths B. The area under the curve increases and the peak shifts to longer wavelengths C. The area under the curve decreases and the peak shifts to shorter wavelengths D. The area under the curve decreases and the peak shifts to longer wavelengths

A. The area under the curve increases and the peak shifts to shorter wavelengths

18. Star C looks blue, while star D looks red. A. True B. False C. impossible to tell

A. True (more blue, the shorter the peak wavelength)

What method could detect a planet in an orbit that is face-on to the Earth?

Astronomical Technique

Imagine that you are looking at two different spectra of the Sun. One spectrum is obtained using a telescope that is in a high orbit far above Earth's atmosphere. The other spectrum is obtained using a telescope located on the surface of Earth. Which one is obtained from the Earth's surface?

B

Which of the three spectra is from the star that is moving the fastest? Is this star moving toward or away from the observer?

B because moving away because it is red shifted.

19. Star C is larger than star D. A. True B. False C. impossible to tell

B. False (longer peak wavelength = larger star)

9. Astronomers discover a new object in our solar system, orbiting perpendicular to the ecliptic plane. This object is most likely a(n) A. asteroid. B. comet. C. planet. D. trans-Neptunian object.

B. comet.

6. If a star, called Grits, is 100 times more luminous than the Sun and is 5 times farther away from Earth than the Sun, how much brighter/fainter would it appear to us when compared to the Sun? A. 20 times brighter B. 20 times fainter C. 4 times brighter D. 4 times fainter

C. 4 times brighter

7. Which comparison between the terrestrial and Jovian planets is FALSE? A. Jovian planets are larger than terrestrial planets. B. Jovian planets are cooler than terrestrial planets. C. Jovian planets are denser than terrestrial planets. D. Jovian planets are composed of lighter elements than the terrestrial planets.

C. Jovian planets are denser than terrestrial planets.

13. If you heat a rock until it glows, its spectrum will be: A. an absorption line spectrum. B. an emission line spectrum. C. a thermal radiation spectrum (continuous). D. no spectrum can come from a rock

C. a thermal radiation spectrum (continuous).

20. What do we need to measure in order to determine a star's luminosity? A. apparent brightness and mass B. apparent brightness and temperature C. apparent brightness and distance D. it is not possible to determine a star's luminosity

C. apparent brightness and distance

2. Which one of the following is FALSE? Compared to the violet end of the visible light portion of the spectrum, the red portion of the visible spectrum has A. longer wavelength B. lower frequency C. higher speed D. lower energy E. none of the above

C. higher speed

10. Venus rotates on its axis in the opposite direction from other planets because A. Venus was formed that way. B. of differentiation. C. of a collision with another body. D. of Jupiter's tidal forces.

C. of a collision with another body.

12. Stars X and Y have the same surface temperature, but star X is actually more luminous than star Y. What can you conclude about the size of star X? A. both stars are the same size. B. star X must be smaller than star Y. C. star X must be larger than star Y. D. not enough information

C. star X must be larger than star Y.

8. Trans-Neptunian objects are typically located A. within the asteroid belt. B. near the Jovian planets. C. within the Kuiper belt.

C. within the Kuiper belt.

Astronomers discover a new object in solar system, orbiting a perpendicular to the ecliptic plane. The object is most likely a...

Comet (because asteroids are in line of ecliptic, so are the planets). the trans neptunian object is a kuiper belt object, which is past neptune but still in line of ecliptic

Kirchoff's Laws

Continuum, absorption, emission line spectra

Which shows the absorption with the shortest wavelength?

D (arrow from the center going outward, longest one)

11. The outer planets were able to capture huge gaseous atmospheres while the inner ones could not because they were A. cooler. B. farther from the Sun. C. more massive. D. All of the above.

D. All of the above.

3. An electron in an atom absorbs a photon and jumps from level 1 to level 3. It then decays from level 3 to level 2 and then from level 2 to level 1. Which of the statements below is true? A. The 2 emitted photons have higher frequencies than the absorbed photon. B. The 2 emitted photons have shorter wavelengths than the absorbed photon. C. The speeds of the two emitted photons are less than that of the absorbed photon. D. The combined energy of the 2 emitted photons is equal to that of the absorbed photon. E. The speeds of the two emitted photons are greater than that of the absorbed photon.

D. The combined energy of the 2 emitted photons is equal to that of the absorbed photon.

1. Which of the following is FALSE? A. Light, radio, ultraviolet, and gamma rays are all forms of electromagnetic radiation. B. Emission spectra are characterized by narrow, bright lines of different colors. C. An absorption spectrum appears as a continuous spectrum interrupted by a series of dark lines. D. The wavelengths of the emission lines produced by an element are different from the wavelengths of an absorption line produced by the same element.

D. The wavelengths of the emission lines produced by an element are different from the wavelengths of an absorption line produced by the same element.

5. If you use a dispersion grating to look at an incandescent light bulb, you will see A. dark absorption lines only. B. a continuous spectrum with dark absorption lines. C. bright emission lines only. D. a continuous spectrum only.

D. a continuous spectrum only.

4. Which of the following is FALSE? If an electron moves from a lower to a higher energy level, A. the atom may become ionized if the electron has enough energy to escape. B. the atom is in an excited state. C. the spectrum of the gas shows an absorption line. D. the spectrum of the gas shows an emission line.

D. the spectrum of the gas shows an emission line.

15. Which shows the emission with the LONGEST wavelength? A. B. C. D. E.

E. The inward facing shortest arrow

The top panel in the figure below shows the optical spectrum for a star. The bottom four panels show emission line spectra corresponding to four different elements. According to the star's spectrum, which of these elements can be found in the star's atmosphere?

Element A and C

Matching the spectrum questions

Emission graph = curved line upwards (like a bowl) absorption graph = curved downwards with lines protruding out

Star C is larger than Star D. True or False

False. Star C is smaller than star D because Star C is hotter but has same luminosity as Star D.

14. Which shows the absorption with the LONGEST wavelength? Figure: A. B. C. D. E.

Figure B - goes from inner most circle to the follow circle

Which planets are generally the easiest to find using the transit method?

Larger planets close to their host stars

Does the pattern of absorption lines change the visible color of the star significantly?

No

Do systems of planets around other stars look like our Solar system? If not, what does that mean about the Solar Nebula theory?

No, many jovian-like exoplanets are close to their stars. we have to revise the nebular theory for planet formation. maybe the planets formed far away from stars, but migrated inward?

Relationship between peak wavelength (color) of light emitted by a hot, opaque source ( a blackbody) and its temperature

Peak wavelength is inversely proportional to temperature ex. the shorter peak wavelength of the light emitted by an object the higher the objects temperature

Transit light curves are shown below for two different exoplanetary systems. Assuming both planets are orbiting stars of the same size, which of the two planets is larger? (also assume the light curves below are plotted using the same scale) (Planet A has a larger curve)

Planet A

The figure shows the radial velocity curve of a star that has an extrasolar planet orbiting around it. From the observer's perspective, match the position on the curve to the position of the star in the orbit. The planet is marked by a blue circle.

Position G:star at 1, Position H:star at 2, Position A:star at 3, Position B:star at 4, Position C:star at 5, Position E:star at 6

Best telescope to build?

Reflecting because more durable, made bigger and less expensive

Why do we see Saturn's rings and not rings around other Jovian planets?

Saturn's rings have a lot of ice and reflect sun. the other jovian planets don't have rings

Order the objects below according to their relative sizes, starting with the largest (1) and ending with the smallest (6). A) Jupiter B) The Solar System C) a typical comet D) The Oort Cloud E) Earth F) the Sun

Solar System, Oort Cloud, Sun, Jupiter, Earth, Comet

Which star has the highest temperature?

Star A because wavelength tells you the temperature, peaks at shortest wavelength

Solar system families

Sun, rocky planets, asteroid belt, gas giant planets, kuiper belt and trans-neptunian objects, oort cloud

List of characteristics and their difference between terrestrial and jovian planets

Terrestrial: Inner Planets - Small, Rocky, dense, close to sun, have few moons, moderate atmospheres, slow rotation rate, no rings. Jovian: outer planets, large, gaseous, low density, far from the sun, have many moons, have many rings, thick atmospheres, first rotation rate

What happens to the gravitational force when you change the mass or change the separation distance?

The large the mass, the greater the attraction. the larger the separation, the smaller the attraction

So, if we see a planet or a moon with a lot of craters, what does this imply?

The object is geologically inactive and has a thin atmosphere

How does the solar nebular hypothesis explain the formation of our solar system?

The solar system formed from a large cloud of cold gas and dust called the solar nebula. 1. a rotating, collapsing ball of gas turns into a disk like shape 2. matter collects in the center where the temperatures increase (much cooler farther out from the center) 3. collisions dominated the early solar system

A space probe is at the halfway point between Earth and Moon moving toward Earth purely propelled by gravity. Would it speed up? When would it experience the greatest acceleration?

The space probe would speed up as it moves toward Earth and it would experience the greatest acceleration at the surface of Earth.

Draw the diagram in your notes and label where the spaceprobe would be when the gravitational force by Earth on the spaceprobe is strongest?

The spaceprobe would be on the surface of Earth

Is the Earth's gravity pulling on these astronauts in the Space Shuttle?

Yes

Small rocky planets close to Sun

inner planets. rocky materials with dense iron cores and high average densities. Earth, Mars, Venus Mercury

Which types of planets are easiest to discover with these methods?

large planets close to their respective stars

Light gathering power of a telescope (how each depends on the size of telescope and/or wavelength of light observed)

larger telescope = better the image. depends on the area of the collecting surface. larger telescope provides a brighter (not bigger) image

absorption

lower -> higher level (arrow going away from nucleus)

Using the blackbody curves shown in the figure, match the correct response.

neither star:Has a lower surface temperature, neither star:Looks red, both stars same:Looks blue, Star B only:Has a greater energy output

Do objects moving perpendicular to our line of sight show any doppler shift?

no

kuiper belt

objects (outside of the orbit of neptune). asteroid size, icy.

Large gaseous planets far away

outer planets. primarily light elements such as hydrogen and helium. low average densities. Jupiter, Saturn, Uranus, Neptune.

Continuous:

produced by a hot solid (or liquid or gas)

Which method gives us the mass of the planet

radial velocity technique

A space probe is at the halfway point between Earth and Moon. If the space probe lost ability to control its motion and was sitting at rest at the midpoint between Earth and the Moon, would the space probe stay at the midpoint or would it start to move?

space probe would start moving towards earth

Oort Cloud

spherical cloud of comets. far past pluto. nearly a light year from the Sun.

all ______ produce dark line absorption spectra

stars

The mass ratio for the sun to the earth is like the mass ration of an elephant to what

tadpole

Doppler Effect

the change in wavelength of radiation due to relative motion between the source and the observer along the line of sight. Only happens if the object which is emitting light is moving towards you or away from you

I measure a wavelength of a spectral line in the lab (at rest) at 300.7 nm. I measure the same line in a star's spectrum to have a wavelength of 302.8 nm. What can I say about this star?

the star is moving away from me

Suppose the Sun were nine times more massive than it now is, and the size and shape of the Earth's orbit were unchanged. Would the year be longer, shorter, or unchanged? If longer or shorter, by how many times? (Of course we would still call whatever time it took the Earth to orbit the Sun "1 year", but express your answer in terms of our current year.)[Hint: you may need to use Newton's version of Kepler's law]

the year would be 1/3 of our current year

Earth, Venus and Mars do not have hydrogen and helium in their atmospheres because

they are not massive enough, not cold enough, hydrogen and helium are low mass elements.

Which exoplanet detection technique allows us to measure the mass of an exoplanet?

transit technique (gives you the size)

which method gives us the radius of the planet?

transits

Refracting Telescope:

uses a lens to concentrate incoming light

Reflecting Telescope:

uses mirrors to concentrate incoming starlight

excitation

when electron is in an energy level above the lowest possible one

Use the figure from the previous question. When would you be able to see a transit of the exoplanet?

when star is at 1

Redshift

when the source of light is moving away from the observer the wavelength of the emitted light will appear to increase

Blueshift

when the source of light is moving towards the observer the wavelength of the emitted light will appear to decrease