## Astronomy C

Test your knowledge of various Science Olympiad events.
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### Re: Astronomy C

Not here to answer, but props for the fancy diagram/driving the question marathon of the best event .
Dang thanks syo, means a lot
```a. Neptune-mass planets with periods <~10 days do not exist or are very rare
b. No, because Neptune-mass planets with greater periods were observed, and also planets with both less mass and more mass than Neptune were observed with short periods
c. Transit photometry
i. From the information given, an increase of mass appears to have little affect on whether a detection through transit was made
i. The amount of radial velocity observed from a system is proportional to the momentum of the planet, or the velocity times the mass of the planet. We know from the vis-viva equation that larger orbital distances result in less velocity, so the amount of radial velocity detected from the star will be lower, making it harder to detect.
e. Hot Jupiters```
```a. yup that's it
b. Just to elaborate further (to your correct answer), Neptune mass planets have been found farther away from their parent stars (which is harder to detect by RV and transit than if it is closer) which means that if we can find them far away from their parent stars, it should easier to find them closer to their stars (but we haven't been able to find any which mean's something's up)
c. yup
c.i. the answer I was looking for was along the lines of transit is mainly based on radius of the planet but if you increase the mass of a planet, that doesn't necessarily mean you're increasing the radius of the planet. In fact, after the planet is about 1.7-2 Jupiter masses, when you add more mass to the planet, it becomes smaller (i.e. the radius shrinks) because the more mass => more self-gravity => more pulling on each other => more closer => more smaller. In this case, adding more mass would make it harder, not easier to be detected by transit
d. yes
d.i. What I was looking for was that the transits go away at farther distances while the RV discoveries are still there, albeit in lesser quantities. This could be explained by saying that with RV, unless i = 0 degrees, you're always going to be seeing some RV shift, it's just that it gets harder and harder to detect. However, with transits, if you go even a bit too far out, you won't be able to have a transit while you might still be able to detect the faint tugs in RV. Essentially, transit detection falls away faster than RV because it's harder for transits to exist the farther you got out while RV still exists, just a lot less (if that makes any sense lol)
e. hot jupiters, exactly!```
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Magikarpmaster629
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### Re: Astronomy C

Pfft, I don't know how to write detailed questions on diagrams >_<...
`[img]http://imgur.com/XXLcc1b.jpg[/img]`
1. The image shows the light curve of which DSO?
2. What is the cause of the "blip" in the light curve during each transit?
3. What is odd about the orbit of this DSO?
4. List two alternate designations for this object.

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Posts: 473
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### Re: Astronomy C

Pfft, I don't know how to write detailed questions on diagrams >_<...
`[img]http://imgur.com/XXLcc1b.jpg[/img]`
1. The image shows the light curve of which DSO?
2. What is the cause of the "blip" in the light curve during each transit?
3. What is odd about the orbit of this DSO?
4. List two alternate designations for this object.
```1. HAT-P-11b
2. Sunspot on HAT-P-11
3. It is very inclined (about 103 degrees)
4. Kepler-3b and KOI-3b```
University of Texas at Austin '22
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Magikarpmaster629
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### Re: Astronomy C

Pfft, I don't know how to write detailed questions on diagrams >_<...
`[img]http://imgur.com/XXLcc1b.jpg[/img]`
1. The image shows the light curve of which DSO?
2. What is the cause of the "blip" in the light curve during each transit?
3. What is odd about the orbit of this DSO?
4. List two alternate designations for this object.
```1. HAT-P-11b
2. Sunspot on HAT-P-11
3. It is very inclined (about 103 degrees)
4. Kepler-3b and KOI-3b```

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### Re: Astronomy C

Pfft, I don't know how to write detailed questions on diagrams >_<...
`[img]http://imgur.com/XXLcc1b.jpg[/img]`
1. The image shows the light curve of which DSO?
2. What is the cause of the "blip" in the light curve during each transit?
3. What is odd about the orbit of this DSO?
4. List two alternate designations for this object.
There's one slight thing that made me hesitant to answer though that I want to bring up too. Looking at the blips in your picture, they seem to come at intervals of 5 transits, making it seem like the ratio of orbits and star's rotations is 5:1. However, according to Bécky et al. this ratio should be 6:1 (http://arxiv.org/pdf/1403.7526v1.pdf), as illustrated by Figure 3 on page 3. It shows various transit light curves, with every sixth light curve having the same sunspot. Similarly, in Figure 6, there's a big spike in the height of the bar every 6th transit. Although a minor detail, this actually threw me off a lot because I assumed that it must have been a different star. Do you know anything about this, or is it just a differeing result from experimentation?
Pfft, I don't know how to write detailed questions on diagrams >_<...
`[img]http://imgur.com/XXLcc1b.jpg[/img]`
1. The image shows the light curve of which DSO?
2. What is the cause of the "blip" in the light curve during each transit?
3. What is odd about the orbit of this DSO?
4. List two alternate designations for this object.
```1. HAT-P-11b
2. Sunspot on HAT-P-11
3. It is very inclined (about 103 degrees)
4. Kepler-3b and KOI-3b```
Anyways, here's my question: Consider the following image. It shows two panels of four images each. Each image inside the panel shows four snapshots in time of the masses of planets at various distances away from their parent star. The left panel shows a disk with a planetesimal surface density as in the minimal mass solar nebula, while in the right panel the surface density is five times as high. 3c and 3d are somewhat unrelated to the picture but still fit in.

1. Is the growth of planetesmials faster or slower at smaller distances?
2. Do planetesmials close to the parent star stop accreting mass before or after their counterparts farther away from the parent star?
3a. In both panels, there is a nearly vertical dashed line towards the middle at around 3AU. What boundary does this represent?
3b. What could explain the sharp increase in mass there?
3c. Is there a positive or negative correlation between planet mass and its metallicity?
3d. Is there a positive or negative correlation between planet mass and overall metal content (the raw mass of metals)?
4. In the right panel, where the surface density of the planetesmial is higher, do protoplanets grow to higher or lower masses and faster or slower than at lower densities?
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Magikarpmaster629
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### Re: Astronomy C

There's one slight thing that made me hesitant to answer though that I want to bring up too. Looking at the blips in your picture, they seem to come at intervals of 5 transits, making it seem like the ratio of orbits and star's rotations is 5:1. However, according to Bécky et al. this ratio should be 6:1 (http://arxiv.org/pdf/1403.7526v1.pdf), as illustrated by Figure 3 on page 3. It shows various transit light curves, with every sixth light curve having the same sunspot. Similarly, in Figure 6, there's a big spike in the height of the bar every 6th transit. Although a minor detail, this actually threw me off a lot because I assumed that it must have been a different star. Do you know anything about this, or is it just a differeing result from experimentation?
I have in my notes that it is 6:1, not 5:1. I also have that the sunspots shift in positions which is why only some light curves have the sunspots, and that the shifting positions is likely similar to the butterfly diagram of the sun (I assume you know more about this than I do since you did Solar System). Besides that, I don't know, maybe you found a flaw in their research? I'll leave it to syo_astro if he would know anything about this.
```1. Faster
2. Before, since they accrete mass faster
3a. Frost line
3b. Past the frost line, volatile 'gasses' are solid and can accrete into planetesimals whereas before the frost line they cannot
3c. Negative, since gas giants are the heaviest type of planet and they typically consist primarily of hydrogen and helium
3d. Positive, since although gas giants have lower metallicities than terrestrial planets and ice giants, they have large metallic cores heavier than terrestrial planets
4. A higher surface density correlates to higher planetesimal mass and faster planetesimal growth```

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Posts: 473
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### Re: Astronomy C

There's one slight thing that made me hesitant to answer though that I want to bring up too. Looking at the blips in your picture, they seem to come at intervals of 5 transits, making it seem like the ratio of orbits and star's rotations is 5:1. However, according to Bécky et al. this ratio should be 6:1 (http://arxiv.org/pdf/1403.7526v1.pdf), as illustrated by Figure 3 on page 3. It shows various transit light curves, with every sixth light curve having the same sunspot. Similarly, in Figure 6, there's a big spike in the height of the bar every 6th transit. Although a minor detail, this actually threw me off a lot because I assumed that it must have been a different star. Do you know anything about this, or is it just a differeing result from experimentation?
I have in my notes that it is 6:1, not 5:1. I also have that the sunspots shift in positions which is why only some light curves have the sunspots, and that the shifting positions is likely similar to the butterfly diagram of the sun (I assume you know more about this than I do since you did Solar System). Besides that, I don't know, maybe you found a flaw in their research? I'll leave it to syo_astro if he would know anything about this.
```1. Faster
2. Before, since they accrete mass faster
3a. Frost line
3b. Past the frost line, volatile 'gasses' are solid and can accrete into planetesimals whereas before the frost line they cannot
3c. Negative, since gas giants are the heaviest type of planet and they typically consist primarily of hydrogen and helium
3d. Positive, since although gas giants have lower metallicities than terrestrial planets and ice giants, they have large metallic cores heavier than terrestrial planets
4. A higher surface density correlates to higher planetesimal mass and faster planetesimal growth```
You got everything exactly right! Nice job, your turn
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Magikarpmaster629
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### Re: Astronomy C

Good luck at state, Adi! I hope to see you at nationals!

1. What type of diagram is this?
2. What data is plotted (what types of objects)?
3. Beta Pictoris b most likely belongs to what spectral class?
4. What do the green and pink lines represent, and which one does the data shown fit better?
5. How many times brighter is 2MASS-0103 AB b than HR 8799 b in the L' band?

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Magikarpmaster629
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### Re: Astronomy C

*cough* Adi1008 or someone else please answer my questions *cough*

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### Re: Astronomy C

Good luck at state, Adi! I hope to see you at nationals!

1. What type of diagram is this?
2. What data is plotted (what types of objects)?
3. Beta Pictoris b most likely belongs to what spectral class?
4. What do the green and pink lines represent, and which one does the data shown fit better?
5. How many times brighter is 2MASS-0103 AB b than HR 8799 b in the L' band?
```1. This is a color-magnitude diagram.
2. The magnitude in the L' band (in the infrared range) versus the difference in magnitude between the H and L' bands of various cool stars (red dwarves and brown dwarves) and exoplanets.
3. Beta Pictoris b most likely belongs to spectral class L.
4. The green and pink lines represent different models for the formation of brown dwarves and large planets.  The green line fits the data shown better.
6. 2MASS-0103 AB b is about 23 times brighter than HR8799 b in the L' band.```
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