Download 2010 Regional Test

Question 1 (3 points): M33 is an example of a(n):
a) globular cluster
b) spiral galaxy
c) elliptical galaxy
d) irregular galaxy
e) planetary nebula
f) lenticular galaxy
Question 2 (4): The Milky Way is known to harbor a massive black hole at its center. What is the approximate mass, in solar masses, of this black hole?
a) 1 million solar masses
b) 10,000 solar masses
c) 350,000 solar masses
d) 4 million solar masses
e) 10 million solar masses
f) 120,000 solar masses
Question 3 (4): One of the important questions in the history of astronomy was whether or not “spiral nebulae” were small groups of stars contained within our own Milky Way Galaxy, or were indeed their own separate galaxies, far distant from the Milky Way. What was the observation (discovery) made by Edwin Hubble in 1925 that firmly settled this issue?
a) observation that light from galaxies is red­shifted
b) observation of a supernova in the Andromeda galaxy
c) measurements of rotational velocity curves of galaxies
d) measurements of individual Cepheid variable periods in galaxies
e) observations of super­massive black holes at the centers of galaxies
f) observation that some galaxies are elliptical in shape
Question 4 (4): M82 is considered a “starburst” galaxy. What is the approximate star formation rate of M82?
a) 1 solar mass per year
b) 10 solar masses per year
c) 100 solar masses per year
d) 1,000 solar masses per year
e) 10,000 solar masses per year
f) 100,000 solar masses per year
Question 5 (4): The galaxy pictured above is a(n):
a) elliptical galaxy
b) irregular galaxy
c) spiral galaxy
d) ring galaxy
e) lenticular galaxy
Question 6 (4): In a galaxy like the Milky Way, how often do supernovae of any type occur?
a) A few supernovae per million years
b) a few supernovae per century
c) a few supernovae per year
d) a few supernovae per day
e) Supernovae do not occur in galaxies like the Milky Way, only in distant, older galaxies
For questions 8­10, refer to the following figure and scenario: You are an astronomer observing an edge­on, unresolved spiral galaxy. You take a spectrum of the entire galaxy, and focus in on the emission line shown below, centered in your spectrum at 6200 angstroms (1 angstrom = 10­10 meters).
Question 7 (7): What is the approximate rotational velocity of this galaxy, assuming that the broadening of the line above is entirely due to Doppler broadening? Assume the galaxy rotates uniformly.
a) 1000 kilometers per second (km/s)
b) 110 km/s
c) 4,850 km/s
d) 2,600 km/s
e) 250 km/s
Question 8 (7): What is the galaxy's redshift, if the line above has a rest wavelength of 5007 angstroms?
a) 0.24
b) 0.19
c) 1.19
d) 0.083
e) 0.76
f) 0.51
Question 9 (5): If you knew nothing at all about this galaxy, which of the following would be a good indication that this is, in fact, a spiral galaxy?
a) Elliptical galaxies cannot be observed at this wavelength
b) Spectra of elliptical galaxies do not typically show any redshift, because they are all close to us
c) Spectra of elliptical galaxies typically do not contain emission lines, while spectra of spiral galaxies often do
d) (a) and (b) only
e) (a) and (c) only
f) (a), (b), and (c)
Question 10 (3): What is the approximate currently accepted value for the Hubble constant (the rate at which galaxies recede from each other)?
a) ~20 km/s/Mpc
b) ~50 km/s/Mpc
c) ~70 km/s/Mpc
d) ~100 km/s/Mpc
e) ~150 km/s/Mpc
For Questions 11 and 12, refer to the figure below
Question 11 (4): Which of the lines in the figure above would correspond to a Hubble constant of 200 km/s/Mpc?
a) a – dotted line
b) b – solid line
c) c – dashed line
d) d – triangles
e) e – plus signs
Question 12 (4): If the Hubble constant were 40 km/s/Mpc, between which two lines in the above figure would it fall?
a) between a (dotted line) and b (solid line)
b) between b (solid line) and c (dashed line)
c) between c (dashed line) and d (triangles)
d) between d (triangles) and e (plus signs)
e) none of the above (would fall below a (dotted line) or above e (plus signs))
Question 13 (7): A Cepheid variable star is observed in a galaxy of unknown distance, with an apparent magnitude of mV = 21.2. Its period is observed to be 124.8 hours. If the relationship between period and intrinsic luminosity is given by
MV = ­2.81 log (P) – 1.43
where P is given in days, find the distance to the host galaxy in kiloparsecs, neglecting attenuation/extinction.
a) 359 kpc
b) 2,895 kpc
c) 1,732 kpc
d) 847 kpc
e) 612 kpc
f) 2,081 kpc
Question 14 (6): Which of the following pieces of observational evidence is used to classify supernovae as type I or type II?
a) type I supernovae result from the explosions of massive stars; type II result from the explosions of white dwarfs
b) type I supernovae do not show hydrogen lines in their spectra; type II supernovae do show hydrogen lines
c) type I supernovae are only observed in spiral galaxies; type II are only observed in ellipticals
d) type I supernovae result from the explosions of white dwarfs; type II result from the explosion of massive stars
e) type I supernovae are only observed in elliptical galaxies; type II are only observed in spirals
f) type I supernovae show hydrogen lines in their spectra; type II supernovae do not show hydrogen lines
Question 15 (6): In which of the environments below would you be most likely to observe Population II stars?
a) In the spiral arms of a spiral galaxy
b) In the bulge or nucleus of a spiral galaxy
c) In globular clusters
d) In elliptical galaxies
e) (a) and (d) only
f) (b), (c), and (d) only
g) (a), (b), and (c) only
Question 16 (7): You observe a quasar and determine its redshift to be z = 3.65. What is the approximate recessional velocity of this quasar, with respect to Earth?
a) 273,000 km/s
b) 286,000 km/s
c) 129,000 km/s
d) 82,000 km/s
e) 211,000 km/s
f) 258,000 km/s
Question 17 (3): What type of object is NGC 604?
a) Spiral galaxy
b) Elliptical galaxy
c) H II region
d) Globular cluster
e) Lenticular galaxy
f) Super­massive black hole
Question 18 (4): The above figure is a galactic rotation curve for a spiral galaxy, showing the rotation speeds of stars around the center of the galaxy as a function of radial distance. Curves such as this one are used as direct evidence for what physical phenomenon?
a) a super­massive black hole at the center of the galaxy
b) dark matter
c) dark energy
d) inflationary cosmology
e) steady­state cosmology
Question 19 (7 – 1 point each): Consider only type Ia and type II supernovae, and fill in the blanks with either:
a) type Ia supernova
or b) type II supernova
____ results from explosion of a white dwarf, pushed beyond the point of stability
____ commonly observed in both spiral and elliptical galaxies
____ result from explosions of short­lived, massive stars
____ nearly uniform in brightness, therefore used as cosmological distance indicators
____ often occur in open clusters of stars
____ sometimes show a plateau (flat­region) of brightness in their light curves
____ observations used as evidence for dark energy
Question 20 (7): An X­ray binary system similar to M33 X­7 consists of an 80 solar­mass star and a 19 solar­mass black hole. If the orbital period of the system is 2.8 days, use Kepler's laws to determine the separation between the two bodies in astronomical units (AU). (note: 1 solar mass = 2 x 1030 kilograms, 1 AU = 1.5 x 1011 meters).
a) 0.27 AU
b) 0.09 AU
c) 1.1 AU
d) 0.72 AU
e) 0.18 AU
f) 0.0029 AU
Tiebreaker­ Answer ONLY after all questions have been completed:
Assume that the age of the universe was determined by an independent method to be 18 billion years old. Assuming no acceleration or deceleration of the expansion rate, determine what Hubble's constant would be in this universe, in units of km/s/Mpc (standard units for Hubble's constant). Show your work and explain any reasoning. You may use the back of this sheet if necessary.
2010 Sample Astronomy Event
Key
1. B
2. D
3. D
4. B
5. C
6. B
7. E
8. A
9. C
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
C
E
A
D
B
F
A
C
B
A, A, B, A, B, B, A
E