Upload
others
View
16
Download
0
Embed Size (px)
Citation preview
AST 2010, Exam 2, Winter 2014 Prof. Bonvicini
1
AST 2010: Descriptive Astronomy EXAM 2
March 3, 2014
DO NOT open the exam until instructed to. Please read through the instructions below and fill out your details on the Scantron form.
Instructions
1. The exam consists of 50 multiple choice questions.
2. There will be 1 hour and 45 minutes to complete the exam.
3. Answers are to be marked on the Scantron answer sheet provided.
4. A list of useful equations and constants are provided. No student notes are allowed.
5. Please answer using a No. 2 pencil only (pen will not be read by the machine).
6. Read the instructions on the answer sheet for how to mark your answers correctly.
7. Scientific calculators are allowed, however, cell phones are not.
8. Use of cell phones will be considered cheating and will result in a 0.
9. Cheating of any sort is not tolerated and will result in a 0 and potential further
action.
Please now fill in your Last Name, First Name and student ID number in the relevant boxes on the Scantron form. There is no need to fill in the Birth date, Sex or Grade/Education.
AST 2010, Exam 2, Winter 2014 Prof. Bonvicini
2
Physical Constants
Name Symbol Value Speed of light c 3 × 108 m s-‐1 Gravitational constant G 6.67 × 10-‐11 m3 kg-‐1 s-‐2 Planck’s constant h 6.63 × 10-‐34 J s Stefan-‐Boltzmann constant σ 6.67 ×10-‐8 W m-‐2 K-‐4 Wien’s law constant T × λmax 2.90 × 106 K nm
Astronomical Constants
Name Symbol Value Astronomical Unit AU 1.50 × 1011 m Light-‐year ly 9.46 × 1015 m = 63,240 AU Parsec pc 3.09 × 1016 m = 206,265 AU = 3.26 ly Year (synodic) yr 365.2422 days = 3.1557 × 107 s Mass of Earth M⊕ 5.97 × 1024 kg Mass of Sun M
! 1.99 × 1030 kg
Equatorial radius of Earth
R⊕ 6378 km
Radius of Sun R! 6.96 × 108 m
Luminosity of Sun L! 3.83 × 1026 W
Hubble’s constant H0 72 km s-‐1 Mpc-‐1
Some useful equations
Geometry
Circumference of a circle = 2πR
Area of a circle = πR2
Surface area of a sphere = 4πR2
Volume of sphere = !! πR3
Distance Relationships
Distance – velocity – time: d = v × t
Linear size -‐ angular size: l = d × α/57.3° Distance from parallax: d (in parsecs) = 1/p(in arcsec)
Hubble’s law (for distance galaxies): d = v/H0
AST 2010, Exam 2, Winter 2014 Prof. Bonvicini
3
Gravity
Kepler’s 3rd Law: P2 = a3 when P is in years and a is in AU
Gravitational force between two masses: 𝐹! =! ! !!!
Gravitational potential energy: 𝐸! = − ! ! !!
Newton’s modified form of Kepler’s 3rd law: 𝑀! + 𝑀! = !!
!! (for d in AU and P in years)
Mass of object for orbital speed v and at distance R: 𝑀 = ! !!
!
Escape velocity: 𝑣!"# = !!"!
Light
Frequency (ν) – wavelength (λ) relation: λ × ν = c
Energy of a photon: 𝐸 = ℎ × 𝜈 = ! × !!
Stefan-‐Boltzmann law: L = σT4 × (surface area)
Wien’s Law: 𝑇 = !.!×!!! ! !"
!!"#
Brightness (B) – Luminosity (L) relation: 𝐵 = !!!!!
Doppler effect: Radial velocity = VR = 𝑐 × !"!
Other Physical Relationships
Density = Mass / Volume
Newton’s 2nd Law: F = m × a
Kinetic Energy: KE = ½ m × v2
Conservation of angular momentum: Mass × Circular velocity × Radius = constant
AST 2010, Exam 2, Winter 2014 Prof. Bonvicini
4
Questions
1. The ability of a telescope to detect fine detail is called a. Finesse b. Persistence c. Focus d. Aperture e. Resolution
2. The aperture of a telescope if determined by the area of its primary mirror or lens a. True b. False
3. The device used to detect light in digital cameras is called a. Electron modulator b. Photomultiplier tube c. False color image d. CCD (or charge-‐coupled device) e. Aperture
4. The largest telescopes are the optical telescopes a. True b. False
AST 2010, Exam 2, Winter 2014 Prof. Bonvicini
5
5. When looking through a green ____________, you see only the green light coming from each object.
a. Aperture b. Coherent c. Filter d. Collecting area e. None of the above
6. If the radius of a telescope’s mirror is doubled, the surface area increases by a. 2 times b. 3 times c. 4 times d. 8 times e. None of the above
7. The diagram below displays an example of a a. Refracting telescope b. Newtonian telescope c. Cassegrain telescope d. Copernican telescope e. None of the above
AST 2010, Exam 2, Winter 2014 Prof. Bonvicini
6
8. A refractor and a reflector have the same diameter aperture. A disadvantage of the reflector is that
a. reflectors allow in less light because it is blocked by the secondary mirror
b. reflectors have less magnification c. reflectors do not direct all light to the same place d. None of the above
9. How does the speed of light in glass compare to in space? a. Faster in glass b. Faster in space c. Same in both
10. The bending of light around corners or edges is called: a. Resolution b. Refraction c. Interference d. Interferometer e. Diffraction
11. The angular resolution of a telescope is determined by the _______________ of the telescope and the _____________ of the radiation being observed.
a. Length, wavelength b. Length, color c. Size of the aperture, brightness d. Size of the aperture, wavelength e. None of the above
12. The wavelength regions where the atmosphere does not absorb radiation are called
AST 2010, Exam 2, Winter 2014 Prof. Bonvicini
7
a. Adaptive optics b. Atmospheric windows c. Light pollution d. Scintillation e. Seeing
13. ________________ is a measure of the steadiness of the atmosphere during astronomical observations.
a. Adaptive optics b. Atmospheric windows c. Light pollution d. Scintillation e. Seeing
14. The Sun’s visible surface is called the a. Solar corona b. Solar Wind c. Sunspots d. Chromosphere e. Photosphere
15. The process of converting hydrogen into helium in the Sun is called what? a. Radioactive decay b. Neutrino production c. Nuclear fusion d. Nuclear fission e. None of the above
16. On average, the time between solar activity maxima is a. 1 year b. 11 years c. 22 years d. 33 years
AST 2010, Exam 2, Winter 2014 Prof. Bonvicini
8
e. 111 years
17. Colder visible regions of the Sun are called a. Aurora b. Coronal mass ejections c. Flares d. Sunspots e. Prominences
18. On the Sun, the equator rotates faster than the area around the poles a. True b. False
19. A parallax angle of 1 arcsecond means that an object is at a distance of ___________ . a. 1 A.U. b. 1 light-‐year c. 1 parsec d. 1 kiloparsec e. None of the above
20. The method of triangulation is good for measuring distances a. Within the solar system b. To nearby stars c. Within our galaxy d. To nearby galaxies e. None of the above
AST 2010, Exam 2, Winter 2014 Prof. Bonvicini
9
21. The amount of light reaching us from a star is called luminosity a. True b. False
22. Star A is 10 times brighter than star B, but they have the same luminosity. Which star is closer?
a. Star A b. Star B c. Neither, they are at the same distance
23. Cold stars show absorption lines from heavy elements such as Calcium and Titanium oxide in their spectra.
a. True b. False
24. Differences in spectral type mainly reflect differences in a. Temperature b. Composition c. Neither
25. As two stars orbit each other in a binary system their spectral lines get shifted due to eclipses
a. True b. False
26. The Stefan-‐Boltzmann Law gives the ____________ as a function of temperature a. Total power radiated b. Power radiated per unit area c. Power radiated per unit wavelength d. Flux received on Earth
AST 2010, Exam 2, Winter 2014 Prof. Bonvicini
10
e. The wavelength where the emission peaks
27. Suppose there are two stars A and B with the same luminosity. If star A is larger than star B, we can conclude
a. Star A is more massive b. Star B is more massive c. The temperature of star B is lower d. The temperature of star A is lower e. Not enough information to conclude anything
28. In an eclipsing binary star system, the maximum brightness occurs when a. The hotter star passes in front of the cooler star b. The colder star passes in front of the hotter star c. Both stars are visible d. The brightness of the system is constant e. None of the above
29. Below is an H-‐R diagram. Stars in area #1 correspond to a. Main sequence stars b. Brown dwarfs c. Red giants d. Black holes e. White dwarfs
AST 2010, Exam 2, Winter 2014 Prof. Bonvicini
11
30. In the above H-‐R diagram, stars in area #2 correspond to a. Main sequence stars b. Brown dwarfs c. Red giants d. Black holes e. White dwarfs
31. In the above H-‐R diagram, stars in area #3 correspond to a. Main sequence stars b. Brown dwarfs c. Red giants d. Black holes e. White dwarfs
32. The _________ the mass of a star, the longer the time it spends in each stage of its evolution.
a. Higher b. Lower c. Doesn’t Matter
AST 2010, Exam 2, Winter 2014 Prof. Bonvicini
12
33. The Sun is classified as a high-‐mass star. a. True b. False
34. Which of the following do not have enough mass to fuse hydrogen into helium? a. Main sequence stars b. Red giants c. Super giants d. White dwarfs e. Brown dwarfs
35. Which of the following statements about molecular clouds is false? a. The contain hydrogen b. They contain particles coated in ice c. They contain helium d. They contain iron e. The entire cloud contracts as a whole leading to a gigantic protostar
36. Stars spend most of their life on the main sequence a. True b. False
37. When the core of a star contracts it ___________________ . a. Heats up b. Cools down c. Its temperature stays the same
AST 2010, Exam 2, Winter 2014 Prof. Bonvicini
13
38. When entering the giant phase, high mass stars don’t increase in luminosity as much as low mass stars
a. True b. False
39. When a star expands, the surface a. Turns red, heats up and power per square meter is increased b. Turns red, heats up and power per square meter is reduced c. Turns red, cools down and power per square meter is increased d. Turns red, cools down and power per square meter is reduced e. None of the above
40. Variable stars that have no repeated pattern on a light curve are referred to as a. Irregular variables b. Cepheid variables c. RR Lyrae variables d. Mira variables e. Novae
41. The area on the H-‐R diagram where most variable stars are found is called the a. Main sequence b. Supergiant region c. Giant region d. White dwarf region e. Instability strip
42. The period-‐luminosity relation states that longer periods of a Cepheid variable imply higher luminosities
a. True b. False
AST 2010, Exam 2, Winter 2014 Prof. Bonvicini
14
43. From the figure below, where on the evolution time line does the star eject its outer layers?
a. 1 b. 2 c. 3 d. 4 e. 5
44. At the center of a low-‐mass planetary nebula is found a a. Planet b. Black Hole c. Neutron Star d. White Dwarf e. Variable star
45. What best describes the evolution of a sun-‐like star from youngest to oldest? a. Black dwarf, white dwarf, red giant, main sequence, protostar b. Red giant, main sequence, white dwarf, black dwarf, protostar c. Protostar, main sequence, red giant, white dwarf, black dwarf d. Protostar, main sequence, red giant, black dwarf, white dwarf e. Protostar, red giant, main sequence, white dwarf, black dwarf
AST 2010, Exam 2, Winter 2014 Prof. Bonvicini
15
46. Material from a companion star that accretes onto a white dwarf can trigger a chain reaction of fusion called
a. Thermonuclear runaway b. Coronal ejection c. Electron degeneracy d. Mass transfer e. Recurrent nova
47. When the mass of a white dwarf becomes less than the Chandrasekhar limit, it will collapse.
a. True b. False
48. In a high mass star _____________ cannot be used as fuel a. Oxygen b. Carbon c. Nitrogen d. Silicon e. Iron
49. In the late stages of a high-‐mass red giant, elements are in layers with ________ in the core and _________ in the outermost layer.
a. Hydrogen, Helium b. Helium, Hydrogen c. Helium, Silicon d. Iron, Hydrogen e. Hydrogen, Iron