Download 2014 State Test

Astronomy 2014 STATES
Astronomy — 2014 — Answer sheet
Station A (1 pt per question unless marked otherwise)
A1.
A7.
A13.
A19.
A2.
A8.
A14.
A20.
A3.
A9.
A15.
A21.
A4.
A10.
A16.
A5.
A11.
A17.
A6.
A12.
A18.
Station B (1 pt per question unless marked otherwise)
B1.
M
B4.
B7.
B10.
B13.
B16.
B2. (2)
B5.
B8.
B11.
B14.
B17.
B3.
B6.
B9.
B12.
B15.
Station C (1 pt per question unless marked otherwise)
C1.
C4.
C7.
C10.
C13.
C16.
C19.
C2.
C5.
C8.
C11.
C14.
C17.
C20.
C3.
C6.
C9.
C12.
C15.
C18.
C21.
Station D (points per question given in parentheses)
D1. (2)
km/s
D2. (1)
D6. (2)
pc
D7. (2)
mag
D3. (2)
km/s
D8. (2)
mag
D4. (2)
Å
D9. (2)
L
D5. (3)
D10. (3)
Tiebreakers: Station D subscore, Station B subscore, Station C subscore
W/m2
Astronomy 2014 STATES
Astronomy — 2014 — Answer Key
Station A (1 pt per question unless marked otherwise)
A1.
C
A7.
A
A13.
C
A19. Ultraviolet
A2. Visible OR Optical
A8.
A
A14.
B
A20.
C
A3.
B
A9.
D
A15.
D
A21.
C
A4.
B
A10.
B
A16.
B
A5.
G1.9+0.3
A11.
D
A17. SS Cygni
A6.
X-ray
A12.
C
A18.
B
Station B (1 pt per question unless marked otherwise)
B1. 22 M
B4. -2
B7. C
B10. B
B13. C
B16. A
B2. (2) B
B5. A
B8. A
B11. A
B14. A
B17. D
B3. 6
B6. O
B9.
B12. B
B15. C
D
Station C (1 pt per question unless marked otherwise)
C1. A
C4. C
C7. D
C10.
B
C13.
B
C16.
B
C19.
D
C2. D
C5. E
C8. D
C11.
E
C14.
E
C17.
A
C20.
E
C3. G
C6. C
C9. A
C12.
B
C15.
A
C18.
B
C21.
A
Station D (points per question given in parentheses)
D1. (2)
160
D2. (1)
Towards
D3. (2)
D4. (2)
-10 OR -15
4685
km/s
D6. (2) 794
pc
D7. (2) 9.50 OR (1) 10.0
mag
km/s
D8. (2) 0.82 OR (1) 1.6
mag
Å
D9. (2) 40
L
OR (1) 86
D5. (3)
0.4
D10. (3) 2.0 x 10-12
Tiebreakers: Station D subscore, Station B subscore, Station C subscore
W/m2
Astronomy 2014 STATES
Station A
Image identification
Instructions
Use the images provided to answer the questions. For all questions about
parts of the electromagnetic spectrum, choose from the following list:
Gamma ray, Infrared, Microwave, Radio, Ultraviolet, Visible, X-ray
All questions at this station are worth one (1) point.
Astronomy 2014 STATES
Questions A1-A4 use the picture below.
A1. What is the name of the object in the image?
A. T Pyxidis
C. Abell 30
B. NGC 3132
D. W49B
A2. This image was recorded by the Hubble Space
Telescope in which band of light?
A3. What feature visible in the image is most
significant to astronomers?
A. The spiky star at the bottom right
B. The two-stage structure of the nebula
C. The fact that the central star is orange
D. The blue tinge to the outermost shell of gas
A4. What kind of object is pictured here?
A. Supernova remnant
B. Planetary nebula
C. Quasar
D. Wolf-Rayet star
E. Irregular galaxy
Questions A5-A8 are about the object shown in the picture below.
A5. What is the name of the ring-like object
captured in this image?
A6. The colors used in this image represent light in
the range of 1 keV–7.5 keV. What band of light was
recorded?
A7. This object is the remnant of what kind of
supernova?
A. Type Ia
C. Type IIn
B. Type Ib/c
D. Type IIp
A8. Is the ring-like structure physically significant or
just an optical illusion, and why?
A. Optical illusion; a thin shell of gas is less visible towards the center than at the edges
B. Optical illusion; the object is rotating so that the center of the image seems empty
C. Physically significant; this type of supernova produces strong jets that were pointed in
the plane of the sky
Astronomy 2014 STATES
D. Physically significant; we are looking at an accretion disk around a massive compact
object that isn’t visible at these wavelengths
Questions A9-A11 use the image below.
A9. Which object is shown in the image at right?
A. GRS 1915+105
C. Eta Carinae
B. Tycho’s SNR
D. W49B
A10. The image is a composite of separate images
taken by the Chandra space telescope, the Very
Large Array, and the Palomar Observatory. Which
of the following is one of the bands of light used
for this image?
A. Microwave
C. Ultraviolet
B. Infrared
D. Gamma-ray
A11. The unusual barrel shape of the remnant very
strongly suggests that the supernova had what
uncommon feature?
A. Incomplete detonation
C. Double core
B. Underluminous plateau phase
D. Strong bipolar jets
Questions A12-A14 use the image below, showing the expansion of two radiobright blobs away from a central source.
A12. Which object is imaged at left?
A. RX J0806.3+1527 C. GRS 1915+105
B. Vela SNR
D. NGC 1846
A13. If the jets are aligned perfectly with the plane
of the sky, then the distance of the left-hand blob
from the central object is roughly 5500 AU on April
16th. How fast must that blob be moving to have
covered that distance in that time?
A. 10% of light speed
B. 67% of light speed
C. 105% of light speed
D. 180% of light speed
A14. The radio-faint object at the center of the
system is most likely what kind of object?
A. T Tauri variable C. Distant quasar
B. Black hole
D. Millinova
Astronomy 2014 STATES
Questions A15-A17 use the following image, showing the light curve of a variable
star (or star system).
A15. About how many magnitudes separate maximum and minimum brightness for this object?
A. 1 mag
B. 2 mag
C. 3 mag
D. 4 mag
A16. What kind of variable star/system is shown by the light curve above?
A. Type I Cepheid
C. T Tauri variable
B. Dwarf nova
D. RR Lyrae variable
A17. What object’s light curve is shown above?
Questions A18-A21 use the image below.
A18. What object is shown in the optical-light
image at right?
A. 47 Tucanae
C. T Pyxidis
B. NGC 3132
D. Vela SNR
A19. Of the two stars in the center, the dimmer
one is the source of the light that powers the
nebula. At a surface temperature of 100,000K,
what kind of light does it primarily emit?
A20. What kind of star is powering the nebula?
A. Neutron star
B. Luminous blue variable
C. White dwarf
D. R Monocerotis variable
A21. The distance to the object is estimated to be 2000 light years. Given its size and rate of
angular expansion, the age is estimated to be roughly 9000 years. If the distance estimate is
revised to be 3000 light years, what happens to the age estimate?
A. Increased to 27,000 years
C. Stays at 9,000 years
B. Increased to 13,500 years
D. Decreases to 6,000 years
Astronomy 2014 STATES
Station B
Stellar evolution
Instructions
Answer the questions on your response sheet.
Unless specified otherwise, all questions are worth one (1) point.
Astronomy 2014 STATES
Questions B1-B6 use the following figure, reproduced from Alexander Heger’s
simulations of stellar evolution.
B1. What is the initial mass of the star described here, in units of the solar mass? Round your
answer to the nearest whole number.
B2. (2 pts) What is the approximate mass loss rate for the first 90 million years of this star’s life,
according to the diagram?
A. 1 x 10-10 M/yr
C. 1 x 10-6 M/yr
B. 1 x 10-8 M/yr
D. 1 x 10-4 M/yr
B3. To the nearest integer, where on the x-axis does the star transition to a red supergiant?
B4. To the nearest integer, where on the x-axis does production of iron start in the star’s core?
B5. What will be the eventual fate of this star?
A. Type II supernova
C. Pair-instability supernova
B. Type Ib/c supernova
D. Planetary nebula
B6. What is the spectral class of this star at birth?
Astronomy 2014 STATES
B7. The most important single factor in determining the lifetime and eventual fate of a star is its
A. Location in its host galaxy
C. Mass
B. Metallicity
D. Wind strength
B8. Which is more luminous: a 3000K star with a radius of 50 R, or a 7500K star with a radius
of just 3.5 R?
A. The large, cool star
C. Both are equally luminous
B. The small, hot star
D. More information is needed
B9. In a binary star system, one star may transfer mass to the other. What is the name of this
process?
A. Lagrange exchange
C. Wien barrier mass loss
B. Tidal stream transfer
D. Roche lobe overflow
B10. The process mentioned in question B9 is responsible for which variety of variable star?
A. S Doradus
C. Mira
B. Recurrent novae
D. T Tauri
B11. While a star is on the main sequence, the vast majority of its energy comes from burning
what element as fuel?
A. Hydrogen
C. Carbon
B. Helium
D. Neon
B12. The electron capture required for turning a proton into a neutron (needed to burn hydrogen into helium) releases a very light particle that interacts extremely weakly with matter.
What is the name of that particle?
A. Charm quark
C. Exciton
B. Neutrino
D. Z boson
B13. Which of the following do we perceive as the color of a star?
A. Luminosity
C. Temperature
B. Hα line intensity
D. Coronal activity
B14. What is the name of the maximum luminosity a star can maintain stably?
A. Eddington luminosity
C. Penrose bound
B. Burbridge limit
D. Herschel sustained maximum
B15. What is the end point of fusion for a star whose mass is 0.3 M ?
A. None; fusion never starts
C. Helium
B. Hydrogen
D. Oxygen
B16. What is the end point of fusion for the Sun?
A. Oxygen
C. Magnesium
B. Neon
D. Iron
B17. What is the rough minimum mass for a star to burn all the way to iron at its core?
A. 1 M
B. 2 M
C. 4 M
D. 8 M
E. 20 M
Astronomy 2014 STATES
Station C
Variable stars
Instructions
Answer the questions on your response sheet.
All questions at this station are worth one (1) point.
Astronomy 2014 STATES
Questions C1-C5 use the following Hertzsprung-Russell diagram.
C1. Which letter is closest to the position of an S Doradus variable star?
C2. Which letter is closest to the position of a Mira variable star?
C3. Which letter is closest to the position of a dwarf nova star?
C4. Which letter is closest to the position of an RR Lyrae variable star?
C5. Which letter is closest to where a T Tauri variable star will enter the main sequence?
C6. RR Lyrae stars’ variability is due to changes in what quantity/quantities?
A. Temperature
C. Both A and B change
B. Radius
D. Neither A nor B changes
C7. What is the name for the generally accepted mechanism for both RR Lyrae and Cepheid
variables’ pulsations?
A. Pickering pathway
C. Kapteyn overflow
B. Rubin dynamics
D. Eddington valve
C8. In addition to the mechanism mentioned in C7, another similarity between RR Lyrae and
Cepheid variables is their location in which part of the Hertzsprung-Russell diagram?
A. Variability region
C. Hertzsprung zone
B. Cataclysmic gap
D. Instability strip
Astronomy 2014 STATES
C9. Which element’s presence or absence differentiates the spectra of Type I and Type II
supernovae?
A. Hydrogen
C. Silicon
B. Helium
D. Iron
C10. Which type of supernova is associated with gamma-ray bursts?
A. Type Ia
C. Type IIbl
B. Type Ib
D. Type IIn
C11. What kind(s) of compact objects can be left behind after a core-collapse supernova?
A. Black hole
D. Two of A, B, and C
B. Neutron star
E. All three of A, B, and C
C. Nothing left behind
C12. Approximately what fraction of the energy released in a core-collapse supernova is in the
forms of kinetic energy and light?
A. 0.01%
C. 10%
B. 1%
D. 100%
For questions C13-C21, use the list of variable star types below:
A. Pulsar
B. S Doradus
C. Mira
D. RR Lyrae
E. Cepheid
G. T Tauri
F. Dwarf/recurrent nova
C13. Which variety of variable star has the shortest lifetime?
C14. Which variety of variable star has the largest radius?
C15. Which variety of variable star has the smallest radius?
C16. If viewed from a fixed distance from Earth, which variety would be brightest in visible
light?
C17. Which variety of star has the strongest gravity at its surface?
C18. Which variety of variable star is most likely to become a supernova in the future?
C19. Which variety of variable star is most likely to be used to determine the distance to
globular clusters?
C20. Which variety of variable star is most likely to be used to determine the distance to nearby
galaxies?
C21. Which variety of variable star is associated with “glitches” or “starquakes”?
Astronomy 2014 STATES
Station D
Numerical questions
Instructions
Answer the questions on your answer sheet. Use scratch paper for your
work—DO NOT WRITE ON THE TEST. If you need more paper, raise your
hand and one of the volunteers (quickly!) will bring some.
The point values for each question are given in parentheses after the
question number.
Astronomy 2014 STATES
Questions D1-D5 are based off of the following graph from Casares et al. (2014).
The figure at right shows the radial
velocity of the two stars in a binary
system, as a function of the phase
of their orbit.
D1. (2 pts) What is the velocity
difference between the peak and
the trough of the curve marked by
empty circles? Round your answer
to the nearest 10 km/s.
D2. (1 pt) Is the average radial
velocity of the system pointed
towards or away from Earth?
D3. (2 pts) What is the average radial velocity of the system? Round your answer to the
nearest 5 km/s.
D4. (2 pts) The open circles were determined by measuring the Helium II line at 4,686 Å. What
would be the measured wavelength of that line at the trough of that curve, at a radial velocity
of -85 km/s? Round your answer to the nearest Angstrom (Å).
D5. (3 pts) What is the mass ratio (calculated as smaller mass divided by larger mass) of the two
objects in this binary system? Give your answer to one significant figure.
Astronomy 2014 STATES
Questions D6-D10 are about an RR Lyrae variable star.
D6. (2 pts) The measured parallax of this star is 1.26 milliarcseconds. What is the distance to
this star in parsecs? Give your answer to three significant figures.
D7. (2 pts) What is the distance modulus associated with the distance you calculated in D6? If
you didn’t get an answer to D6 or don’t want to use it, you may use 1000 parsecs for one point
instead of 2. Give your answer to three significant figures.
D8. (2 pts) The apparent magnitude of this RR Lyrae variable is 10.32. What is its absolute
magnitude? If you didn’t get an answer to D7 or don’t want to use it, you may use a distance
modulus of 8.72 for one point instead of 2. Give your answer to two significant figures.
D9. (2 pts) What is the luminosity of the star, in units of L? If you didn’t get an answer to D8 or
don’t want to use it, you may use an absolute magnitude of 0.0 for one point instead of 2. Give
your answer to two significant figures.
D10. (3 pts) What is the energy flux at Earth due to this RR Lyrae star, in W/m2? Use scientific
notation, and give your answer to two significant figures.