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Astronomy: Stellar Evolution and Type Ia Supernovae
Dec 10th, 2016
Do not open this booklet until instructed to do so.
You are allowed to separate the packet and work in any order. The packet must
be returned to the event supervisor stapled and in the correct order.
Instructions
1) Please place all answers on the answer sheets provided
NO SCORE WILL BE GIVEN FOR ANSWERS WHICH ARE NOT ON THE
ANSWER SHEETS!
2) For the Essay, make sure your “8 facts” are marked with “dots” or
“bullets”
3) The ESSAY question will be used for the “Tie Breaker”
4) Show ALL WORK on the Math section for credit
5) READ all directions carefully
6) *Good luck!
Team Name____________________________________________________________________
Team Number___________
Student Names_________________________________________________________________________
__________________________________________________________________________________________
Short Response Section I (12 points): *Place all answers on the Answer sheet
1)
2)
3)
4)
5)
6)
7)
8)
9)
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11)
12)
What is the approximate luminosity of a main sequence star with a temperature of 20,000 K?
What is the relationship between temperature and luminosity for stars on the main sequence?
What is the relationship between a star’s size and luminosity?
What is the relationship between a star’s initial mass and lifespan?
In terms of both luminosity and temperature, compare “Sirius” to our Sun:
The star “FR33peEZa” has the same temperature as the star “Rigel” and the same luminosity as “Proxima
Centauri”. What type of star should it be classified as?
At what approximate temperature (in Kelvin) did hydrogen fusion begin in the Sun’s core?
List all the fusion by products of Oxygen in a stellar core (by element):
Approximately what stellar mass (in solar masses) allows for a core density of 2.0 X 105 g/cm3 as well as Carbon
fusion?
Brown Dwarves are too small for proper fusion of hydrogen. What material (if any) are they capable of fusing to
make energy?
What materials are undergoing fusion in the shell of an asymptotic giant branch star?
During what year did Tycho’s SNR actually explode and how many years later did we observe it on Earth?
Multiple Guess Questions Section II: 5 Points *Make sure all final answers are on the Answer Sheet.
1)
The figure to the left (Figure 1) is the light curve of a type Ia
supernova for months after the initial explosion. What elements are
best characterized by “A” and “B” on the graph?
A) Si and O
D) C and O
B) Ni and Co
E) H and He
C) Fe and Mb
*For the next two Questions- refer to the Graph “T” on the Image Sheet- sorted by color: Identify the following events by
their light curves.
2) What does the light curve shown by Red line show?
A) II-P
B) IL-L
C) Ia
D) Ib
E) Eclipsing Binary
3) What does the light curve shown by Blue line show?
A) II-P
B) II-L
C) Ia
D) Ib
E) Eclipsing Binary
4) If the theoretical Helium White Dwarf star were to be discovered, what would that prove?
a) It would provide conclusive proof that the Big Bang theory is correct
b) That the Carbon-Oxygen model for the Sun’s progress into degenerate matter is invalid.
c) It would show that the universe is much older than we currently think it is.
d) That the gravitational upwelling of a White Hole actually exists as a counter to Black Holes.
e) It would verify the Khazzoom-Brooke’s postulate.
f) That Helium the main product of Hydrogen Fusion in a stellar core.
5) Using the Ia Supernova graph at the very bottom (left) side of your image document. There are “dots” with multiple
colors, please use the “dark red” dots for “Unfiltered with Red Zeropoint” for this question. If this Ia supernova event
were a “standard Ia Supernova” of predictable absolute magnitude, please calculate its distance from the Earth.
Which answer is most likely correct?
a) 5.31 X109 ly
d) 9.67 X1026 km
b) 2.11 X107 ly
e) 0.5 ly
c) 6.46 X102 Kpc
Fact Correction Section III (20pts): *Place final answers on the answer sheet
*All of the following FACTS are wrong! Your duty is to CORRECT them by replacing a since word (or number) in each
sentence. Value 1 point each, but only if you can find the exact incorrect word (or letter, or number) and suggest a
logical replacement which turns the wrong fact into a right one.
1) The spectral class of a star is a short code summarizing the hybridization state, giving an objective measure of the
photosphere's temperature and density.
2) A-type stars are very hot and extremely luminous, with most of their radiated output in the ultraviolet range.
3) B-type stars are very luminous and red. Their spectra have neutral helium.
4) A-Type Stars have strong hydrogen lines, at a maximum by A0, and also lines of ionized metals (Fe II, Mg II, C II) at a
maximum at A5.
5) Our Sun is a F2 type star, with prominent H and K lines of Ca II.
6) The most common red giants are stars on the red-giant branch (RGB) that are still fusing hydrogen into helium in a
shell surrounding an inert carbon core.
7) A white dwarf, also called a degenerate dwarf, is a stellar remnant composed mostly of neutron-degenerate matter.
8) The density of a White dwarf is 1 × 109 kg/m3 . Therefore the specific gravity of White Dwarf material is 10,000 SG.
9) A blackbody refers to an opaque object that emits ultraviolet radiation. A perfect blackbody is one that absorbs all
incoming light and does not reflect any.
10) As the temperature of a blackbody increases, the total amount of light emitted per second decreases.
11) According to new research, the use of Ia supernovae as a “Standard Candle” for determining stellar distances might
not always be correct. Reduced amount of X-Rays produced within elliptical galaxies (30 to 50 times less) indicate that Ia
supernovae do not necessarily require mass to be accreted onto a white dwarf from a stellar companion. It has been
theorized that two white dwarves could collide and produce a supernova, and that the masses of these bodies could be
variable. With two ways of creating a Ia supernova, the Rosenberg limit (the point where a white dwarf has accreted
enough mass to ignite) might not always apply when observing a supernova.
12) A dwarf nova is different from a classical nova due to the mechanisms of its origin. Unlike a classical nova, where the
white dwarf companion accretes sufficient matter to react, with dwarf novae is caused by an instability in the accretion
disk. Temperature changes cause a change in viscosity of the disk, which temporarily heats the disk causing it to become
more luminous. Since mass removed from the companion star will be greater than the mass flowing through the disk
during this event, the condition is temporary.
13) AM CVn stars differ from most other cataclysmic variables (CVs) in the abundance of hydrogen lines from their
spectra.
14) Neutron Stars result from the supernova explosion of a massive star, combined with gravitational collapse, that
compresses the core past the white dwarf star density to that of atomic nuclei. Most of the basic models for these
objects imply that neutron stars are composed almost entirely of neutrinos, which are subatomic particles with no net
electrical charge and with slightly larger mass than protons.
15) Mira variables are rapidly losing mass and this material often forms dust shrouds around the star. In some cases
conditions are suitable for the formation of natural pulsars.
16) The Particle Data Group documents quote a "best modern value" of the Hubble parameter as 54 km/s per mega
parsec (+/- 10%). This value comes from the use of type Ia supernovae (which give relative distances to about 5%) along
with data from Cepheid variables gathered by the Hubble Space Telescope.
17) The composition of Globular clusters indicates that there are abundant low-metal, old stars. The variety of stars
found in the cluster are often close to those found the central bulge of their parent galaxy. Globular clusters also have
an abundance of interstellar gas and dust, due to a prolonged period of star formation.
18) Electron degeneracy is a stellar application of the Pauli Exclusion Principle, as is neutron degeneracy. No two
electrons can occupy identical states, even under the pressure of a collapsing star of several solar masses. For stellar
masses less than about 1.44 solar masses, the energy from the gravitational collapse is not sufficient to produce the
neutrons of a neutron star, so the collapse is halted by electron degeneracy to form white dwarfs. This maximum mass
for a white dwarf is called the Chandrasekhar limit. As the star contracts, all the lowest electron energy levels are filled
and the electrons are forced into higher and higher energy levels, filling the highest unoccupied energy levels. This
creates an effective pressure which prevents further gravitational collapse.
19) Kepler’s 3rd law: The Square of the orbital period of a planet is proportional to the square of the semi-major axis of
its orbit.
20) Medium mass stars, like our Sun, live by fusing the oxygen within their cores into helium.
Mathematics Section IV: 16 Points *Each question in this section is worth up to 4 points. Partial credit may be awarded
for an incomplete or incorrect answer in some instances. PLEASE SHOW ALL WORK ON THE ANSWER SHEETS
1)
Please estimate how close a 0.5 solar mass white dwarf must come to the center of a 2 solar mass subgiant
companion (which has a radius 10 times more than that of our sun) in order for the white dwarf’s tidal field to
strip matter from the companion’s surface. Answer in km to 3 significant digits.
2) Use a “radius – luminosity – temperature” relation to calculate the radius of a 12,000 K and 0.0004 solar
luminosity white dwarf (answer in km to 3 significant digits).
3) What is the escape speed (in km/s) and surface gravity (relative to Earth gravities) of Sirius B? (use the
following data for Sirius B; 1.1 solar mass, and 0.008 solar radii). Answer in “km/s” (for escape speed), and
“Earth gravities” to three significant digits please.
4) If a type Ia Supernovae has an apparent magnitude of -13.5 (and is a “perfect theoretical model” at the
Chandrasekhar limit for an Ia supernova), what is its distance in parsecs? (to the nearest one tenth)
Image Matching Section V: 31 points. Please write all answers on the answer sheet:
Please read Carefully: In this section you will be given a “Clue” for one of the Deep Space Objects used in this year’s
competition. Next to each clue you must determine the name of the DSO and also the image letter of the DSO from the
image sheet provided to you with your test packet. The image selected must be the closest one associated with the DSO
in the clue. In this section you will awarded 1 point for each DSO name and 1 point per Image letter that you get correct.
ALERT!!!*At least ONE of these bodies has TWO images associated with it. In that case, ONE point will be awarded for
EACH image. However, if the second image is not correct then NO credit will be awarded for the image portion of that
question at all.
DSO BANK: J075141/J174140, NGC 2392, SNR 0509-67.5, Omicron Ceti, SN 2011fe, SNR G1.9 +0.3, NGC 2440, Henize 2248, Henize 3-1357 (Stingray Nebula), Tycho’s SNR, SS Cygni, M15, HM Cancri, Sirius A & B, NGC 1846, and NGC 6960.
15 Clues for 31 points in this section:
1) Clue: Larger companion classified “Am” due to deep metallic absorption lines indicating that it is 316% as iron rich as
our own Sun. The smaller companion is approximately Earth size, but is surprisingly nearly TWICE as dense as it should
be for its estimated mass.
2) Clue: Strange collimated outflows of gas, imperfectly understood, from this very early stage planetary nebula.
3) Clue: A possible view into the future of our own Solar System. Early astronomers could have mistaken this body as a
Planetary Disk. This particular sample might have two bodies at the center, indicated by elevated X-Ray emissions.
4) Clue: Most probably the result of a Ia supernovae as indicated by traces of Silicon and Iron, as well as a fortunate
“light echo” of the initial explosion delayed by 400 years.
5) Clue: White dwarf binary system with the shortest orbital period known (approx. 5.4 minutes). These two bodies are
in a decaying orbit, closing in on each other at approximately 60 cm per day. Here, their “degenerate dance of death” is
shown as an artist’s representation.
6) Clue: Reached a 10th magnitude in brightness (visible to amateur astronomers), during August of 2011, despite being
over 20 million light years away from Earth.
7) Clue: “AM CVn” class of objects. Theoretical source of “space time ripples” due to colliding white dwarves. These two
particular bodies have an orbital period of 18 minutes, which is still far from the shortest discovered to date.
8) Clue: A sneaky white dwarf stealing matter from its Red Giant companion. Exhibits a “bow shock” on its way to
becoming a planetary nebula.
9) Clue: Youngest known supernovae remnant (observed).
10) Clue: A planetary nebula surrounding what may be the hottest known white dwarf remnant. Close by, at only 4000
light years distant from our Sun.
11) Clue: Asymmetric planetary nebula indicates a binary core of two white dwarves. At time of discovery, it was the
most massive system of its kind known. A type Ia supernovae is expected to result in only about 700 million years as
their orbit degrades.
12) Clue: The remains of a Supernova seen on Earth in 1572 and help influence the development of modern astronomy.
13) Clue: Cataclysmic variable, binary system between a red dwarf and a white dwarf.
14) Clue: Densely packed globular cluster surrounding what appears to be a black hole.
15) Clue: This is a spherical collection of hundreds of thousands of stars in the outer halo of the Large Magellanic Cloud.
A
B
C
D
E
F
G
H
I
J
K
L
M
N
P
R
O
Q
S
T
ESSAY QUESTION SECTION VI: (up to 16 points may be awarded for this
section, and this question is used to break TIES! *Answer on the answer
sheets provided):
In this section you will write a 700 word (approx.) essay about the
following topic:
“How have discoveries concerning Ia Supernovae changed our
understanding of the universe?”
For this competition you have learned about type Ia Supernovae, but and
not all type Ia events are the same. For this essay, compare and contrast
the different theories for how a type Ia supernova could be generated. If
possible, show an “evolution” of theories from the past to the present. Be
certain to present at least three of this year’s DSO objects in your essay.
In your Essay you must:
1) Include at least THREE “DSO” objects from this year’s competition, each with facts that are both “substantial and
relevant”. Failure to use at least three DSO objects properly will cause a deduction in score. Using more than
three DSO objects correctly will “break ties” between examinations.
2) You MUST use facts that are both “Substantial” and “Relevant”. Up to 8 points may be awarded for each essay
with facts that meet this criteria (•Which are also BULLETED so that they stand out in the document).
3) You may use more than 8 facts in your essay, but you should choose the BEST EIGHT of those facts to be the
ones you wish to use for point scoring. Those specific facts must be marked with a “bullet”. They do not have to
be written “in a list” format and may be embedded within the paragraph so long as they are marked with a
“Bullet” or “Dot” ● to indicate the factual information you wish to present for scoring.
4) If more than 8 facts are “Bulleted”, only the first 8 facts will be counted and measured for overall quality.
*Rules Clarifications:
Substantial: Each science fact must contain specific and detailed information. For example; “Planets have
been found around other stars.” is not very substantial, unless you can provide technical details on HOW these
planets have been discovered.
Relevant: Science facts that you know will only be counted if you can show how they are part of, or relate to,
the Essay above. Example; “Jumping Tracts” to speak about the Ergosphere of a black hole is not worth credit
unless it makes sense for this topic.
*Bullets: To ensure that you receive credit for your science facts- please either bullet them or mark
them with a ● so that they stand out. If you present more than 8 facts, only the first 8 with a bullet or mark
will be evaluated.
Legibility: We cannot grade exams we cannot read. Please print or write very neatly. Corrections are
acceptable as long as the sections to be scored can be clearly read.
Length: Please try to keep your essay down to approximately 700 words OR LESS.
Points for Style: Up to 8 points will be awarded for the “Style” of your essay. Do the facts ‘flow’ consistently?
Is your essay clear, logical, and easy to follow? Did you make it engaging, creative, and informative? Essays will
be split into 4 basic “tiers” for style. Each “tier” will be split into a “lessor or greater” section based on the
overall quality of the essay.
0pts: This “essay” is merely a collection of facts with no real format.
1-2pts: Essay is structured, but poorly structured, or is confusing/difficult to understand.
3-4pts: Essay is easy to follow, with acceptable structure but not particularly engaging or creative.
5-6pts: Essay is well structured, creative, as well as an interesting read, the author has strong ‘voice’ and
‘direction’.
7-8pts: This point category will be awarded to the very best essay we have seen for this exam session. It may
be given only to the very best essay, or to several (possibly 2 or 3) essays if all are similarly impressive.
ANSWER SHEETS- ASTRONOMY ISLIP: Dec 10th, 2016: Stellar Evolution and Type Ia Supernovae
Team Number: ________ School: _________________Students: ___________________, _________________
Short Response SECTION I (12 points):
1) __________________
2) ________________________________
3) ________________________________
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RATER ONLY: SCORE I (12)
Multiple Guess Questions Section II (5 Points)
1) _____
2) _____
3) _____
4) _____
5) _____
RATER ONLY: SCORE II (5)
Fact Correction Section III: (20 points) *Replace one word (or number) with a correct one:
1) Replace: ________________________ with _____________________
2) Replace: ________________________ with _____________________
3) Replace: ________________________ with _____________________
4) Replace: ________________________ with _____________________
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RATER ONLY: SCORE III (20)
Mathematics Section IV: 16 Points *Each question in this section is worth up to 4 points. Partial credit may be awarded
for an incomplete or incorrect answer in some instances. PLEASE SHOW ALL WORK ON THE ANSWER SHEETS
1) Please estimate how close a 0.5 solar mass white dwarf must come to the center of a 2 solar mass subgiant
companion (which has a radius 10 times more than that of our sun) in order for the white dwarf’s tidal field to
strip matter from the companion’s surface. Answer in km to 3 significant digits.
______________________________________________________________________________________________
______________________________________________________________________________________________
______________________________________________________________________________________________
______________________________________________________________________________________________
______________________________________________________________________________________________
2) Use a “radius – luminosity – temperature” relation to calculate the radius of a 12,000 K and 0.0004 solar
luminosity white dwarf (answer in km to 3 significant digits).
______________________________________________________________________________________________
______________________________________________________________________________________________
______________________________________________________________________________________________
______________________________________________________________________________________________
______________________________________________________________________________________________
3) What is the escape speed (in km/s) and surface gravity (relative to Earth gravities) of Sirius B? (use the
following data for Sirius B; 1.1 solar mass, and 0.008 solar radii). Answer in “km/s” (for escape speed), and
“Earth gravities” to three significant digits please.
______________________________________________________________________________________________
______________________________________________________________________________________________
______________________________________________________________________________________________
______________________________________________________________________________________________
______________________________________________________________________________________________
4) If a type Ia Supernovae has an apparent magnitude of -13.5 (and is a “perfect theoretical model” at the
Chandrasekhar limit for an Ia supernova), what is its distance in parsecs? (to the nearest one tenth)
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
RATER ONLY: SCORE IV (16)
Part V. Image Matching Section (2pt/ea): 31 points.
1) Object Name: _______________________
Object Letter: _________
2) Object Name: _______________________
Object Letter: _________
3) Object Name: _______________________
Object Letter: _________
4) Object Name: _______________________
Object Letter: _________
5) Object Name: _______________________
Object Letter: _________
6) Object Name: _______________________
Object Letter: _________
7) Object Name: _______________________
Object Letter: _________
8) Object Name: _______________________
Object Letter: _________
9) Object Name: _______________________
Object Letter: _________
10) Object Name: _______________________
Object Letter: _________
11) Object Name: _______________________
Object Letter: _________
12) Object Name: _______________________
Object Letter: _________
13) Object Name: _______________________
Object Letter: _________
14) Object Name: _______________________
Object Letter: _________
RATER ONLY: SCORE VI (16pts Essay)
RATER ONLY: FINAL TEST SCORE (100)
15) Object Name: _______________________
Object Letter: _________
RATER ONLY: SCORE V (31)
ESSAY QUESTION SECTION V: up to 16 points may be awarded for this section, and this question used to break TIES!
*Answer on the answer sheets provided:
In this section you will write a 700 word (approx.) essay about the following topic:
“How have discoveries concerning Ia Supernovae changed our understanding of the universe?”
(*Remember to “dot” or “bullet” the 8 facts you wish to count for credit and include at least 3 DSOs)
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