# Homework Help: Question regarding temperature of a star and its solar system/planets

1. Oct 25, 2015

### ezach1

1. The problem statement, all variables and given/known data

a) The peak intensity of light from the Sun occurs at a wavelength of 500 nm. Astronomers discover a nearby star, “Nus”, which is the same size and mass as the Sun, but has a peak wavelength of half this value. Is Nus hotter or colder than the Sun and by how much?

Nus is discovered to have eight planets in orbit. These eight planets are separated from Nus at precisely the same distances as the planets in our own Solar System are from the Sun. Do you expect that this system will be comprised of greater, fewer or the same number of giant planets as the Solar System, and why? [6 pts] c) The third planet from Nus, Htrae, has a single large moon, Noom. Astronomers learn that the Noom has a low density, has plenty of volatiles and that Htrae is spinning extremely rapidly. Based on this information, what is the most favorable hypothesis explaining the origin of Noom?

Im currently working on part a and I think I came up with 11,700 kelvin...
I would say that the system will be comprised of the same number as the solar system due to the fact the gas giants would be beyond the frostline where the suns heat would start to diminish, kind of like in our solar system. The heavier elements like rock and metal will stay inside the frost line and that might even lead to more terrestrial-like planets in Nus' system, but the lighter elements like hydrogen and helium are captured by the planets with enough mass to do so outside of the frostline.
Anyone wanna correct me?
Noom has a lower density because the impact of giant protoplanetary collision gouged out the outer crust and mantle, and didn’t eject so much of the Htrae's iron core.The huge cloud of ejected debris coalesced into the Noom. The object that collided with Htrae mustve been huge and abundant in volatiles, hence the traces in its composition.
Is it safe to say the fast spinning of Htrae has to do with the the size of the object that collided with it?

2. Relevant equations

3. The attempt at a solution

I would say that the system will be comprised of the same number as the solar system due to the fact the gas giants would be beyond the frostline where the suns heat would start to diminish, kind of like in our solar system. The heavier elements like rock and metal will stay inside the frost line and that might even lead to more terrestrial-like planets in Nus' system, but the lighter elements like hydrogen and helium are captured by the planets with enough mass to do so outside of the frostline.
Anyone wanna correct me?
Noom has a lower density because the impact of giant protoplanetary collision gouged out the outer crust and mantle, and didn’t eject so much of the Htrae's iron core.The huge cloud of ejected debris coalesced into the Noom. The object that collided with Htrae mustve been huge and abundant in volatiles, hence the traces in its composition.
Is it safe to say the fast spinning of Htrae has to do with the the size of the object that collided with it?

2. Oct 25, 2015

### Simon Bridge

Just qualitatively, does a smaller wavelength imply a larger or smaller temperature?
Is Nus, therefore, hotter or colder than the Sun?

In the moon formation, you are arguing that the moon was formed by a collision ... consider all the different ways two objects can collide and what effect each way would have on the final angular momentum of each object?

3. Oct 25, 2015

### ezach1

Nus is almost twice as hot as the sun..I believe the smaller the wavelength, the hotter the temp..
As for momemtum,...im not quite sure what you mean. Do you mean other theories regarding moon formations? ex; fission, etc?

4. Oct 25, 2015

### Simon Bridge

Well done - so where is Nun's frost line in relation to the Sun's frost line?

No, I mean use your understanding of how things collide in general ... if you hurled a lump of wet clay at a bigger limp of wet clay... some stick, you get bits breaking off, and the resulting bits may spin. What affects how fast (what's left of) the target ends up spinning?

5. Oct 25, 2015

### ezach1

The frost line would be further out. Not sure how I would term that.
As for the collision...force?

6. Oct 25, 2015

### Simon Bridge

You said, in your answer, that the gas giants would still be beyond the frostline ... how can you be sure if the frostline is further away?

I think you need to throw some stuff at some other stuff and watch ... sure, a high force impact will get higher rates of spin if the impact is the kind that would leave the target spinning in the first place. Think in terms of the geometry of the impact. i.e. if two objects collide so their incoming velocities are in line with their centers of mass, would that make for a spinning end result?

Last edited: Oct 25, 2015
7. Oct 26, 2015

### ezach1

So is it safe to assume the frost line would be further away? I know we shouldn't assume this but I don't know any other way. If there's a frost line then there will be planets made up of lighter elements. I assume. Lol
As for the spinning Htrae, I believe the force will cause it to spin rapidly. I'm guessing it was hit at an angle or trajectory that caused the impact at a certain point where the planetary object would've nearly missed Htrae, but didn't.
Yes???

8. Oct 26, 2015

### ezach1

And am I right on the volatiles part?

9. Oct 26, 2015

### ezach1

Nus' frostline would be twice as far as the Suns frost line.