Explain the gravitational instability theory of gas giant formation, and some of its flaws.
Consider a disk of gas and dust, where the radius of the disk is much greater than the thickness of the disk. The disk is massive enough so that its self gravity makes it unstable, so that if perturbed, it will collapse. When denser parts of the disk collapse, they fragment the disk, which go on to form dense gas cores, but don't have solids. This is a top-down approach (the core-accretion model is a bottom-up approach), where the atmosphere forms before the solid core. The gaseous core accretes more gas, and once it gets massive enough, solids, which fall to the center of the gas cloud and form the core (since they are denser)
Problems:
-does not allow for massive cores
-does not seem to create smaller gas planets like Neptune and Uranus
-can only act in the early stages of the protoplanetary disk, before solar wind blows away the gas
-does not explain the formation of terrestrial planets (it isn't a theory that can cover all of planet formation)
Stanford University
University of Texas at Austin '22
Seven Lakes High School '18
Beckendorff Junior High '14
Explain the gravitational instability theory of gas giant formation, and some of its flaws.
Consider a disk of gas and dust, where the radius of the disk is much greater than the thickness of the disk. The disk is massive enough so that its self gravity makes it unstable, so that if perturbed, it will collapse. When denser parts of the disk collapse, they fragment the disk, which go on to form dense gas cores, but don't have solids. This is a top-down approach (the core-accretion model is a bottom-up approach), where the atmosphere forms before the solid core. The gaseous core accretes more gas, and once it gets massive enough, solids, which fall to the center of the gas cloud and form the core (since they are denser)
Problems:
-does not allow for massive cores
-does not seem to create smaller gas planets like Neptune and Uranus
-can only act in the early stages of the protoplanetary disk, before solar wind blows away the gas
-does not explain the formation of terrestrial planets (it isn't a theory that can cover all of planet formation)
Great! Go ahead.
Ladue Science Olympiad (2014ish-2017)
A wild goose flies over a pond, leaving behind a voice in the wind.
A man passes through this world, leaving behind a name.
Explain the gravitational instability theory of gas giant formation, and some of its flaws.
Consider a disk of gas and dust, where the radius of the disk is much greater than the thickness of the disk. The disk is massive enough so that its self gravity makes it unstable, so that if perturbed, it will collapse. When denser parts of the disk collapse, they fragment the disk, which go on to form dense gas cores, but don't have solids. This is a top-down approach (the core-accretion model is a bottom-up approach), where the atmosphere forms before the solid core. The gaseous core accretes more gas, and once it gets massive enough, solids, which fall to the center of the gas cloud and form the core (since they are denser)
Problems:
-does not allow for massive cores
-does not seem to create smaller gas planets like Neptune and Uranus
-can only act in the early stages of the protoplanetary disk, before solar wind blows away the gas
-does not explain the formation of terrestrial planets (it isn't a theory that can cover all of planet formation)
Great! Go ahead.
Consider the following image:
a. What does this image imply about the occurrence of very short-period planets with of similar mass to Neptune?
b. Could the answer to (a) be explained solely by observational biases? Why or why not?
c. Planets that are shown with a blue dot are discovered using which type of method?
i. Does an increase in the mass of a planet, holding the distance from the parent star constant, always result in making the planet easier to detect using such method?
d. Planets that are shown with a green dot are discovered using which type of method?
i. What explains the lack of discoveries using the transit method at farther distances when there are still many green dots?
e. What type of exoplanet is best represented by the cluster of yellow dots in the top left?
Also, considering how much of the nationals test for Astronomy is identification/image based, I think it would be good if we started to incorporate them into our questions
Stanford University
University of Texas at Austin '22
Seven Lakes High School '18
Beckendorff Junior High '14
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
d. Radial velocity
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
Ladue Science Olympiad (2014ish-2017)
A wild goose flies over a pond, leaving behind a voice in the wind.
A man passes through this world, leaving behind a name.
syo_astro wrote:Not here to answer, but props for the fancy diagram/driving the question marathon of the best event .
Dang thanks syo, means a lot
Magikarpmaster629 wrote:
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
d. Radial velocity
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!
Your turn!!
Stanford University
University of Texas at Austin '22
Seven Lakes High School '18
Beckendorff Junior High '14
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.
Ladue Science Olympiad (2014ish-2017)
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 wrote: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
Stanford University
University of Texas at Austin '22
Seven Lakes High School '18
Beckendorff Junior High '14
Magikarpmaster629 wrote: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
Great, your turn.
Ladue Science Olympiad (2014ish-2017)
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 wrote: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?
Magikarpmaster629 wrote:
Adi1008 wrote:
Magikarpmaster629 wrote: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
Great, your turn.
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?
Stanford University
University of Texas at Austin '22
Seven Lakes High School '18
Beckendorff Junior High '14
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