Team Number:
Astronomy C Test
Kentucky Science Olympiad 2019
at the
Union College Barbourville, KY
Prepared By: Dr. Sunil Karna
Place:
School Name:
School Number:
Team Number:
Student Name:
Score:
Time: 50 minutes
Team Number:
Instructions:
Please show your work and write your answers in the answer sheet
only.
This test consists of two sections: Section 1 contains Deep Sky
Observations (DSO) and section 2 contains Graphs and Theory
(Math and Conceptual) problems.
Tiebreakers will be marked with (T1) for the first tiebreaker, (T2)
for the second and so on.
The point value for each question is marked in front of questions.
Constants that you may need in the test:
a. 1 parsec (pc) = 3 × 1016 m
b. 1 megaparsec (Mpc) = 3.2 × 106 ly
c. Mass of the Sun (M ) = 1.989 × 1030 kg
d. Hubble’s Constant (Ho) = 65 km/s/Mpc
e. Absolute Magnitude of Type Ia Supernova (M ) = −19.3.
Good Luck!
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Images (Set A)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
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Team Number:
T
U
Q
P
R
S
V
(a)
(b)
(c)
Page 4
Team Number:
Section A
Q.1)
[4points]
(a) What is the name of object in image 1 in images (set A)?
(b) Find the image of this object taken in X-ray region of EM spectrum in images (set A)?
(c) What letter on the H-R diagram shows the location of the objects hot tail?
(d) What pressure strips away the gas of this object?
Q.2)
[4points]
(a) What is the name of object in image 11 in images (set A)?
(b) In which constellation does this object appear?
(c) What causes the formation of such a spectacular shape of the object?
(d) What is the apparent magnitude of the object?
Q.3)
[4points]
(a) What is the name of object shown in image 2 in images (set A)?
(b) What letter on the H-R diagram corresponds to the location of the object?
(c) What would be the possible cause of formation of onion-skin structure around the object?
(d) In which constellation is this object located?
Q.4)
[4points]
(a) What is the name of X-ray object in image 15 in images (set A)?
(b) What are the brightest source called?
(c) What are the sources in this object which produce such an intense x-ray?
(d) Can you find an another image of Ultra Luminous X-ray Source (ULXs) in images (set A)?
Q.5) Image 12 is a Sombrero Galaxy which is a collection of large number of globular clusters.
[4points]
(a) Do globular clusters typically reside in the disk or halo of galaxies?
(b) Approximately how many stars reside in a globular cluster?
(c) Approximately how many globular clusters reside in the Milky Way Galaxy?
(d) What are Oosterhoff groups?
Q.6) Which classifications of galaxies have similar star populations in their halo and disk?
(a) Sa and Sb
(b) Sa and Sc
(c) Sb and Sd
(d) Sc and Sd
Q.7) Image 16 in images (set A) is a Pictor A Galaxy.
(a) What do the red and blue colors mean?
(b) Where is this galaxy located?
(c) What is a bright spot between the two red lobes?
(d) What is the process of X-ray production in Pictor A?
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[2points]
[4points]
Team Number:
Q.8) Arrange the following methods of calculating nearest to farthest distances using the designated letter.
[2points]
(a) Type Ia SNRs,
(b) Hubble’s Law,
(c) Spectroscopic parallax,
(d) Period-Luminosity relationship.
Q.9) Image 6 in Images (set A) is a supernova remnant called the Lobster Nebula (NGC6357). It
is a cluster of cluster and most prominent sites of massive star formation.
[4points]
(a) What type of stars reside in this nebula?
i. M-type
ii. G-type
iii. A-type
iv. O-type
(b) Where do supernovas take place?
(c) What causes a supernova?
(d) Will our sun ever explode as a supernova?
Q.10)
[3points]
(a) What is kilonova and what it is responsible for?
(b) How does a gravitational wave (GW 170817) relate to a kilonova?
(c) What kind of galaxy is formed if two spiral galaxies merge?
Q.11) Use the Extinction Curve in page 4 to answer the following questions.
[4points]
(a) What does the extinction curve tell us?
(b) What is the effect of smaller grains on extinction ratio, Rv ?
Q.12)
[5points]
(a) Which image in images (set A) depicts depicts Phoenix Cluster?
(b) Which image in images (set A) depicts Antennae Galaxy?
(c) Which image in images (set A) depicts the Medusa Merger Galaxy?
(d) Which image in images (set A) depicts the CL J1001 Galaxy?
(e) Which image in images (set A) depicts the Twin-Jet Nebula?
Q.13)
[5points]
(a) What is the name of the galaxy cluster which has highest rate of star formation?
i. Phoenix Cluster
ii. Perseus Cluster
iii. Abell 1689 Cluster
iv. Bullet Cluster
(b) What two characteristics does the Tully-Fisher Relationship correlate?
i. Luminosity and stellar mass
ii. Luminosity and rotational speed
iii. Radius of star and rotational speed
iv. Recessional velocity and stellar distance
(c) In which region of HR diagram would hosts stars that are in hydrostatic equilibrium?
i. Main Sequence
ii. T
iii. U
iv. S
(d) Which corner of the HR diagram has the stars with the shortest life spans?
i. upper right corner
ii. upper left corner
iii. lower right corner
iv. lower left corner
(e) If two stars have the same temperature, do they necessarily have the same luminosity?
i. Yes
ii. No
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Section B
Q.14) Image 13 in images (set A) is a M106 Galaxy (NGC4258). It has four spiral arms and has
very active black hole at the center.
[8points]
(a) If this galaxy is 23.5 million light years from the earth, calculate its redshift.
(b) Star A has a parallax angle of 0.82 arcseconds and star B has a parallax angle of 0.45 arcseconds.
Which star is closest to the earth, and by how much?
(c) A star has an apparent magnitude of +4.45 and an absolute magnitude of +4.44. Approximately how far away from us is this star? Justify your answer in words, not with calculations.
(d) Imagine that you have discovered a sun-like star of radius 7 × 105 km, and temperature 6000 K
with a binary companion which is 500 times fainter, but has a temperature of 10000 K. What
is the radius of the binary companion (in km)?
Q.15) Except Hydrogen and Helium all the other elements in astronomy are considered as metals. [6points]
(a) What is the color of stars that have high metal content?
(b) If the star’s
h
(c) If the star’s
h
Fe
H
i
ratio is -4, would it have high or low metallicity?
Fe
H
i
ratio is -4, what population star would it be?
Q.16) A period and arrival times of the pulses of a millisecond pulsar has been measured precisely
one day. A week later when it has been observed again then the period is the same but all the
pulses are delayed by 1 micro-second compared to what would have been expected based on the
first day of measurement.
[2points]
If the delay is caused by the pulsar moving...
(a) The pulsar must now be 300 metres closer to the Earth
(b) The pulsar must now be 300 metres further from the Earth
(c) The pulsar must now be 100 metres closer to the Earth
(d) The pulsar must now be 100 metres further from the Earth
Q.17) A star of mass 3.0 × 1030 kg is moving in a circle of radius 1.0 × 1012 metres, with a period of
100 years. This is due to the gravity of a second unseen object which is moving about a barycneter
of radius 312 m. What is the mass of this unseen object (in kg)?
[3points]
Q.18) You have used a Cepheid variable to measure the distance to a nearby spiral galaxy. The
spiral galaxy is 5.0 Mpc (megaparsecs) away. Three years ago, a Type 1a supernova was observed
in this galaxy, and had a peak flux of 6.2 × 10−14 W m−2 .
You have just discovered a new Type 1a supernova in a very distant galaxy. This new supernova
stayed bright for the same time as the one in the nearby spiral galaxy. The flux of the new
supernova was 1.3 × 10−18 W m−2 .
What is the distance to the new supernova (in Mpc)?
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[3points]
Team Number:
Q.19) Imagine that you are monitoring the brightness of a star and you get the graph as shown
in the figure of brightness versus time (light curve).
[4points]
The approximate brightness B of the star when the planet is not blocking any of its light is 45.3
and the change in brightness of the star is 0.7 when the planet is blocking some of its light. If the
radius of the star the planet orbiting is 5 × 108 m.
(a) What is the radius of the planet (in metres)?
(b) Roughly how hot would you expect the surface of this planet to be (in K)? The luminosity of
the star is 1.2 × 1026 W, and the Stefan-Boltzmann constant σ is 5.67 × 10−8 Jm−2 s−1 K −4 .
Q.20) The expansion of the universe redshifts the spectrum of a very far away object. Redshift is
defined as z = ∆λ
λ . Where ∆λ is the change in wavelength (observed wavelength minus laboratory
wavelength) and λ is the laboratory wavelength.
[6points]
Laboratory wavelength is summarized as
For silicon SiII (singly ionized peak): 385.8nm, 413.0nm, 505.1nm, 597.2 nm, 635.2nm.
For Calcium CaII (singly ionized peak): 393.4nm, 396.8nm, 857.9nm.
For Magnesium M gII (singly ionized peak): 448.1nm.
For sulfer SII (singly ionized peak): 546.8nm, 561.2nm, 565.4nm.
For Oxygen OI (neutral peak): 777.3nm.
For Hydrogen lines: Hα = 656.3nm, Hβ = 486.1nm, Hγ = 434.1nm, and 410.2nm, 397.0nm, and
388.9nm.
If in addition the gas is moving along the line of sight at a velocity v, the doppler effect will cause
∆v
its observed wavelength to move by an amount ∆λ given by ∆λ
λ = v . Where c is the velocity of
light and λ is the redshifted wavelength of the line.
The spectrum of a supernova is shown in the figure below.
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Team Number:
(a) What type of supernova is this?
(b) What is the redshift of the supernova?
(c) How fast is the gas flowing out of the supernova?
Q.21) The solid line in the graph to below depicts generic rotation curve of a galaxy. As the radius
from the center of galaxy increases the graph begins to flatten.
[6points]
(a) Explain briefly the predicted curve.
(b) Explain the modern theory that supports the shape
of the observed curve.
(c) A galaxy lies at a distance of 12.5 Mpc from the Earth
(a Mpc = 3.09 × 1022 m). A gas cloud is observed at
an angle of 16.8 arc-minutes from the centre of this
galaxy is orbiting around the centre at a velocity of
200km/s.
What is the total mass of the region between the gas
cloud and the center of the galaxy?
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Q.22) (T3 ) Shown below is an radial velocity curve we have measured for a Sun-like star. The
black circles represent data measured and the blue curve is a fit to the data. [Hint: Use Kepler’s
law]
[4points]
(a) How far from the star is the planet, in AU?
(b) What is the mass of this planet, in Jupiter masses?
Q.23) (T2 ) Shown below are two transit curves for identically sized planets around two different
stars.
[3points]
What is the ratio of the stellar radii? That is, what is the radius of Star 1 compared to Star 2,
RS1 /RS2 ?
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Q.24) Shown below are three radial velocity curves for three identical planets around three different
stars. Each of the orbiting planets has the same mass and the same orbital distance.
[4points]
(a) Which of the planets is around the most massive star?
i. Husker
ii. Starbuck
iii. Appolo
iv. There is not enough information to tell.
(b) Which of the planets is around the least massive star?
i. Husker
ii. Starbuck
iii. Appolo
iv. There is not enough information to tell.
Q.25) (T1 ) Using main-sequence fitting, you show that a nearby dwarf galaxy orbiting our own
is 100 kiloparsecs (kpc) from the Earth. You monitor this galaxy, looking for pulsing stars, and
succeed in finding many cepheid variables. When you plot their flux against their pulsation period,
you find a nice correlation (orange stars below).
[2points]
You want to use the cepheid luminosity/flux relationship
to measure the distance to a far-away giant spiral galaxy.
You have found one cepheid variable in this giant galaxy
- its flux and period are shown as the green star in the
plot above.
What is the distance to the far-away giant spiral galaxy?
i. 17 kpc
ii. 41 kpc
iii. 245 kpc
iv. 600 kpc.
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Team Number:
Astronomy C Test
Kentucky Science Olympiad 2019
at the
Union College Barbourville, KY
ANSWER SHEET
School Name:
School #:
Student Name:
Team #:
Team Number:
Section A
Q.1) (a)
Ans: ESO 137-001 (spiral galaxy)
(b)
Ans: 8
(c)
Ans: Q
(d)
Ans: Ram Pressure
Q.2) (a)
Ans: Bubble Nebula (NGC 7635), or Sharpness 162, Caldwell 11.
(b)
Ans: Cassiopeia
(c)
Ans: The star (SAO 20575, or BD + 60o 2522) near the center of this object.
(d)
Ans: 10
Q.3) (a)
Ans: Cat’s eye (planetry nebula NGC 6543, or Snail nebula, sunflower nebula)
(b)
Ans: P
(c)
Ans: Material is ejected smoothly from the star and the rings are created due to the formation
waves in the outflow material. (steller pulsations and companion star orbiting arround the
dying star.) Star ejects its mass in series of pulses and these convulsions created dust shells.
(d)
Ans: Canes Venatici
Q.4) (a)
Ans: Whirlpool galaxy (M51, or NGC 5194)
(b)
Ans: ULXs (ultraluminous x-ray source)
(c)
Ans: Neutron stars or blackholes
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(d)
Ans: image 10 (Arp 299 galaxy)
Q.5) (a)
Ans: Halo of galaxies
(b)
Ans: hundreds of thousands tomillion of stars
(c)
Ans: 150 globular cluster
(d)
Ans: It is a group of globular cluster. OI and OII have weak lines of metallic elements. (group
I has stronger metallic lines than group II.)
Q.6)
Ans: d.
Q.7) (a)
Ans: Red means radio waves and blue means x-rays.
(b)
Ans: In constellation Pictor in the southern hemisphere.
(c)
Ans: Massive blackholes.
(d)
Ans: Synchrotron radiation. When high speed electron spirals arround the magnetic field, it
produces synchrotron photon in terms of x-ray.
Q.8)
Ans: c, d, a, b.
Q.9) (a)
Ans: iv.
(b)
Ans: In a galaxy
(c)
Ans: When stars of atleast five solar mass go out or a dying white dwarf steals material from
companion star and explode.
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(d)
Ans: No, our sun never explode as supernova as it is a single star and does not have enough
mass to become supernova.
Q.10) (a)
Ans: A kilonova a transient astronomical event that occurs in a compact binary system when
two neutron stars or a neutron star and a blackhole merge into each other. It puts out much
more energy in the form of gravitational waves than supernova.
(b)
Ans: GW170817 is the merger of two neutron stars. These stars corpses are gravitationally
locked and spiriling each other before collapse.
(c)
Ans: The merger of two galaxies produces elliptical galaxy.
Q.11) (a)
Ans: Extinction curve is a plot between absorption and wavelengths. It tells us the attenuation
of star light as it passes through interstellar dust.
(b)
Ans: Rv is smaller for low density regions and larger for high density regions of dust grains.
For larger dust extinction curve is flatter in UV-rise and weaker 2175Å. Steeper Rv for UV-rise
and a stronger 2175Å bump shows smaller dust grains.
Q.12) (a)
Ans: 3
(b)
Ans: 4
(c)
Ans: 5
(d)
Ans: 20
(e)
Ans: 9
Q.13) (a)
Ans: i.
(b)
Ans: ii.
(c)
Ans: i.
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(d)
Ans: ii.
(e)
Ans: ii.
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Section B
Q.14) (a)
d = 23.5 × 106 ly;
Ho = 70km/s/M pc;
Ans :
z=
c = 3 × 105 km/
v
Ho d
70 × 23.5 × 106
= 0.001
=
=
c
c
3.2 × 106 × 3 × 105
(b)
Ans :
1
1
=
= 1.22pc
P1
0.82”
D1 =
D2 =
1
1
= 2.22pc
=
P2
0.45”
D = D2 − D1 = 1pc
theref ore
(c)
Ans: Absolute magnitude is the apparent magnitude of a star if it is placed at 10 pc from
us. Since this star has an absolute magnitude of +4.45 which is almost equal to its apparent
magnitude as seen from earth then it must be about 10 pc from us.
(d)
s
r=r
L
L
T
T
2
L = AσT 4
L
=
L
r
r
2
r
r
2 L
=
L
T
T
4
T
T
4
Ans : 1.12 × 104 km
Q.15) (a)
Ans: Metal rich star looks redder.
(b)
Ans: Low metallicity.
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Team Number:
(c)
Ans: Population II star.
Q.16)
1µs = 3 × 102 = 300m further away due to delay.
Ans: The pulsar must now be 300 metres further from the Earth.
Q.17)
Ans: 9.52 × 1029 kg.
m1 r1 = m2 r2 ⇒ m2 =
and
m1 r1
r2
Gm1 m2
m1 v12
=
r1
(r1 + r2 )2
also
v1 =
2πr1
P1
Gm2
4π 2 r12
2 = r P2
(r1 + r2 )
1 1
Therefore
m2 =
4π 2 r1 (r1 + r2 )2
GP1
Q.18)
Ans: 1091.9 Mpc
As both supernove stay bright for the same
p length of time, they should have comparable luminosities, so the distance of the new one is 6.2 × 10−14 /1.3 × 10−18 times further away than the
nearby one.
From Tully-Fisher relation:
s
Dd = Dc
s
Dlum =
fc
fd
L
4πf
Q.19) (a)
Ans :
6.2 × 107 m
s
f ormula :
rp = rs
Page 7
∆B
B
Team Number:
s
r=
3
GMs p2
4π 2
(b)
Ans :
982.6K
L = 4πσr2 T 4
Q.20) (a)
Ans: type I
(from peak eyeballing)
(b)
Ans: 0.07
(z =
∆λ
λ )
(c)
Ans: 14117
(z =
v
c
=
λpeak −λtrough
)
λpeak
Q.21) (a)
Ans: Predicted curve is the outcome of Newton’s law of gravitation.
GM m
mv 2
=
⇒ vo =
r2
r
s
GM
r
(b)
Ans: If the star is far from galatic cneter it moves with very low speed and centripetal force
may not be strong enough to hold this star in orbit, but we observe they are there rotating
with extremely high speed. This suggests that there must be some unseen mass around the
galaxy which provide this star a very high speed, we call this unseen mass a dark matter.
(c)
Ans :
1.13 × 1042
r = Dθ(rad), M =
rv 2
G
Q.22) (a)
Ans :
a = p2/3 = 9.7AU
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(b)
Ans :
Mp =
P
12
1/3 A
Mj = 0.3Mj
13
Where P is period in years, A is amplitude in m/s. Here P = 15 × 2 = 30years, A = 3m/s.
Q.23)
Ans:
5
Q.24) (a)
(a) Appolo
(b)
(b) Husker)
Q.25)
Ans: (iii.)
The flux of the star in √
the distant galaxy is six times less than that in the nearby
dwarf, so the distant galaxy must be 6 times further away.
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