## Astronomy C

Magikarpmaster629
Exalted Member
Posts: 578
Joined: October 7th, 2014, 3:03 pm
State: MA
Location: No idea, but I can tell you exactly how fast I'm going

### Re: Astronomy C

Let's assume we are on a hypothetical planet which has a perfectly circular orbit around a hypothetical main sequence star. The value of the time it takes the planet to orbit the star in years is exactly half of the value of the mass of the star in solar masses, which is between 2 and 20 solar masses (hint hint). The peak wavelength emitted by the star is 115.9nm and the radius is 3.6789 solar radii. While on the planet, we observe a different star, for which we find the parallax is 35mas. Would we have been able to use geometric parallax to observe this star accurately from Earth, assuming the same relative distance to the star (Using Hipparcos)? What would be the equivalent parallax of this star if observed from Earth?

Information for easy reference:
-Between 2 and 20 solar masses
-115.9nm
-35mas
Alright, kindof an odd question, but not totally un-doable... TL;DR: distance of 299 pcs, Hipparcos doesn't work, parallax of 3.34 mas on Earth.
First I'll assume when you say the period is half the mass, you're using Kepler units, so it's in years not seconds. The second thing I'll assume is that you want me to solve for the mass using the mass-luminosity relation, which people seem to disagree on but I'll say it's L=M^4. Solving for L we get 4779 solar luminosities, which we can plug into the relation above to get M=8.314 solar masses. Plugging this into the period and then Kepler's third law we get 5.238 AU for the semi-major axis of the planet. Solving for the distance we get 299 pcs. Using this link from Hyperphysics (http://hyperphysics.phy-astr.gsu.edu/hb ... arcos.html), Hipparcos can only do up to 200 pcs, so this would not work. On Earth, the angle would be 3.34 mas.

A wild goose flies over a pond, leaving behind a voice in the wind.
A man passes through this world, leaving behind a name.

jonboyage
Member
Posts: 102
Joined: December 13th, 2016, 8:32 am
State: PA

### Re: Astronomy C

Let's assume we are on a hypothetical planet which has a perfectly circular orbit around a hypothetical main sequence star. The value of the time it takes the planet to orbit the star in years is exactly half of the value of the mass of the star in solar masses, which is between 2 and 20 solar masses (hint hint). The peak wavelength emitted by the star is 115.9nm and the radius is 3.6789 solar radii. While on the planet, we observe a different star, for which we find the parallax is 35mas. Would we have been able to use geometric parallax to observe this star accurately from Earth, assuming the same relative distance to the star (Using Hipparcos)? What would be the equivalent parallax of this star if observed from Earth?

Information for easy reference:
-Between 2 and 20 solar masses
-115.9nm
-35mas
Alright, kindof an odd question, but not totally un-doable... TL;DR: distance of 299 pcs, Hipparcos doesn't work, parallax of 3.34 mas on Earth.
First I'll assume when you say the period is half the mass, you're using Kepler units, so it's in years not seconds. The second thing I'll assume is that you want me to solve for the mass using the mass-luminosity relation, which people seem to disagree on but I'll say it's L=M^4. Solving for L we get 4779 solar luminosities, which we can plug into the relation above to get M=8.314 solar masses. Plugging this into the period and then Kepler's third law we get 5.238 AU for the semi-major axis of the planet. Solving for the distance we get 299 pcs. Using this link from Hyperphysics (http://hyperphysics.phy-astr.gsu.edu/hb ... arcos.html), Hipparcos can only do up to 200 pcs, so this would not work. On Earth, the angle would be 3.34 mas.
You got the correct answer although we used slightly different mass luminosity ratios. The reason i mentioned it had to be between 2 and 20 solar masses is because on the wikipedia page the formula for those masses was slightly different. The mass you were supposed to get was close to 10 Your answer was still correct, so your turn!
I was in a bin

Rustin '19
UPenn '23

Magikarpmaster629
Exalted Member
Posts: 578
Joined: October 7th, 2014, 3:03 pm
State: MA
Location: No idea, but I can tell you exactly how fast I'm going

### Re: Astronomy C

Since we've been doing math I'll shift it back towards DSOs:

1. Which DSO is depicted in this image? What galaxy is it in?
2. This DSO was especially bright in a particular wavelength, which is the wavelength used in the image above. Which wavelength is this?
3. The occurrence of this DSO gave insight into the progenitors of events like this. What, most likely, was the progenitor system of this DSO? Be specific.
4. Why was this event so important to cosmology and the field of astronomy as a whole?

A wild goose flies over a pond, leaving behind a voice in the wind.
A man passes through this world, leaving behind a name.

Magikarpmaster629
Exalted Member
Posts: 578
Joined: October 7th, 2014, 3:03 pm
State: MA
Location: No idea, but I can tell you exactly how fast I'm going

### Re: Astronomy C

(Is this still a thing? Was my question too hard? )

A wild goose flies over a pond, leaving behind a voice in the wind.
A man passes through this world, leaving behind a name.

Unome
Moderator
Posts: 4090
Joined: January 26th, 2014, 12:48 pm
State: GA
Location: somewhere in the sciolyverse

### Re: Astronomy C

(Is this still a thing? Was my question too hard? )
I was going to answer it, but I was out of town, and then forgot about it. I'll try and get to it tomorrow (need to sleep).
Userpage
Chattahoochee High School Class of 2018
Georgia Tech Class of 2022

Opinions expressed on this site are not official; the only place for official rules changes and FAQs is soinc.org.

Moderator
Posts: 472
Joined: December 6th, 2013, 1:56 pm
State: TX
Location: Austin, Texas

### Re: Astronomy C

Since we've been doing math I'll shift it back towards DSOs:

1. Which DSO is depicted in this image? What galaxy is it in?
2. This DSO was especially bright in a particular wavelength, which is the wavelength used in the image above. Which wavelength is this?
3. The occurrence of this DSO gave insight into the progenitors of events like this. What, most likely, was the progenitor system of this DSO? Be specific.
4. Why was this event so important to cosmology and the field of astronomy as a whole?
University of Texas at Austin '22
Seven Lakes High School '18
Beckendorff Junior High '14

Magikarpmaster629
Exalted Member
Posts: 578
Joined: October 7th, 2014, 3:03 pm
State: MA
Location: No idea, but I can tell you exactly how fast I'm going

### Re: Astronomy C

Since we've been doing math I'll shift it back towards DSOs:

1. Which DSO is depicted in this image? What galaxy is it in?
2. This DSO was especially bright in a particular wavelength, which is the wavelength used in the image above. Which wavelength is this?
3. The occurrence of this DSO gave insight into the progenitors of events like this. What, most likely, was the progenitor system of this DSO? Be specific.
4. Why was this event so important to cosmology and the field of astronomy as a whole?

A wild goose flies over a pond, leaving behind a voice in the wind.
A man passes through this world, leaving behind a name.

Moderator
Posts: 472
Joined: December 6th, 2013, 1:56 pm
State: TX
Location: Austin, Texas

### Re: Astronomy C

Since we've been doing math I'll shift it back towards DSOs:

1. Which DSO is depicted in this image? What galaxy is it in?
2. This DSO was especially bright in a particular wavelength, which is the wavelength used in the image above. Which wavelength is this?
3. The occurrence of this DSO gave insight into the progenitors of events like this. What, most likely, was the progenitor system of this DSO? Be specific.
4. Why was this event so important to cosmology and the field of astronomy as a whole?

Determine which one(s), if any, are Type Ia supernovae
University of Texas at Austin '22
Seven Lakes High School '18
Beckendorff Junior High '14

Magikarpmaster629
Exalted Member
Posts: 578
Joined: October 7th, 2014, 3:03 pm
State: MA
Location: No idea, but I can tell you exactly how fast I'm going

### Re: Astronomy C

Determine which one(s), if any, are Type Ia supernovae
Only A is an SN Ia (I think)

A wild goose flies over a pond, leaving behind a voice in the wind.
A man passes through this world, leaving behind a name.

Ashernoel
Member
Posts: 336
Joined: January 27th, 2017, 1:31 pm
State: IL
Location: MA

### Re: Astronomy C

Determine which one(s), if any, are Type Ia supernovae
Only A is an SN Ia (I think)
yea. B is II, C is Ic, and D is Ib
NT '19
Harvard '23

Ashernoel
Member
Posts: 336
Joined: January 27th, 2017, 1:31 pm
State: IL
Location: MA

### Re: Astronomy C

Since we've been doing math I'll shift it back towards DSOs:

1. Which DSO is depicted in this image? What galaxy is it in?
2. This DSO was especially bright in a particular wavelength, which is the wavelength used in the image above. Which wavelength is this?
3. The occurrence of this DSO gave insight into the progenitors of events like this. What, most likely, was the progenitor system of this DSO? Be specific.
4. Why was this event so important to cosmology and the field of astronomy as a whole?
The emission spectrum has ruled out the option of a single degenerate progenitor
https://arxiv.org/abs/1502.00646
https://arxiv.org/abs/1111.0966
and that it was double degenerate.
NT '19
Harvard '23

Ashernoel
Member
Posts: 336
Joined: January 27th, 2017, 1:31 pm
State: IL
Location: MA

### Re: Astronomy C

1. What is the catalog number of this object?
2. Which planetary nebula resides in this object?
3. What type of variable can be found and how many pulsars are within this object?
4. Why are there so few PN observed within the DSO?

NT '19
Harvard '23

Moderator
Posts: 472
Joined: December 6th, 2013, 1:56 pm
State: TX
Location: Austin, Texas

### Re: Astronomy C

Determine which one(s), if any, are Type Ia supernovae
Only A is an SN Ia (I think)
You got it!
1. What is the catalog number of this object?
2. Which planetary nebula resides in this object?
3. What type of variable can be found and how many pulsars are within this object?
4. Why are there so few PN observed within the DSO?

The emission spectrum has ruled out the option of a single degenerate progenitor
https://arxiv.org/abs/1502.00646
https://arxiv.org/abs/1111.0966
and that it was double degenerate.
From what I understand, there's a fair amount of controversy surrounding the topic. In general, any one research paper saying something doesn't mean it's true
University of Texas at Austin '22
Seven Lakes High School '18
Beckendorff Junior High '14

Ashernoel
Member
Posts: 336
Joined: January 27th, 2017, 1:31 pm
State: IL
Location: MA

### Re: Astronomy C

The emission spectrum has ruled out the option of a single degenerate progenitor
https://arxiv.org/abs/1502.00646
https://arxiv.org/abs/1111.0966
and that it was double degenerate.
From what I understand, there's a fair amount of controversy surrounding the topic. In general, any one research paper saying something doesn't mean it's true
If it comes up on the nats test, should we cite research papers in our answer? Or say there is controversy? Idk what to do.

Edit: And now its your turn again
NT '19
Harvard '23

Moderator
Posts: 472
Joined: December 6th, 2013, 1:56 pm
State: TX
Location: Austin, Texas

### Re: Astronomy C

For 1 be careful to only list the catalog number
For what it's worth, Messier, NGC, 2MASS, etc are all different types of catalogs, not just NGC. Writing Messier 15, for example, is just writing the designation of that object in the Catalog of Nebulae and Star Clusters by Messier. Similarly, writing NGC 7078 is just writing the designation of that object in the New General Catalogue. I think it would have been more clear if you had specified that you wanted the designation of M15 in the New General Catalogue, which is NGC 7078.
For 4, nice wording I think someone that created a test for a California invitational that you guys one that had identical phrasing
Indeed haha xD
If it comes up on the nats test, should we cite research papers in our answer? Or say there is controversy? Idk what to do.
I don't know either, but from my (admittedly limited) experience at nationals I feel like they'd try to not have a very controversial question in the first place (or phrase it in a way that there are multiple theories to reduce confusion)

Here's my question:

The figure above plots core temperature vs. density for a sun-like star. The dashed line marks the boundary between nondegeneracy and degeneracy

a. Which letter represents the onset of core helium fusion?
b. Which letter(s) represents a possible location of our Sun on thisplot?
c. Which side of the dashed line (left or right) represents a degenerate core?
d. Which letter best represents SAO244567?
e. During which letter (that is, stage of stellar evolution) does this sun-like star spend the most time?
f. Which letter represents the stage where the star undergoes thermal pulses?
g. The luminosity of this star (increases/decreases) going from A to B
h. The luminosity of this star (increases/decreases) going from D to E
i. Which letter(s) represent the location of the object depicted in the image below?

University of Texas at Austin '22
Seven Lakes High School '18
Beckendorff Junior High '14