Astronomy C

[hipparcos]

How have you guys been getting images for exoplanets?

I've just been Googling around, but I don't think there are images for many exoplanets (there are, however, images for some and artist conceptions for the rest...). This is sort of subjective, but among DSOs, I like how the Eye of Sauron of last year, V1647 Ori, has been replaced by a new one.

How do you guys do information on DSOs? When I have time, I actually take notes, but eventually I just run out of time and and copy-paste in relevant webpages.

The event has changed so much this year. Oh my goodness.

I personally use a laptop and ctrl-f. It does mean that I can navigate even when I don't know my notes that well. It also saves trees, I suppose.

[syo_astro]

How have you guys been getting images for exoplanets?

I've just been Googling around, but I don't think there are images for many exoplanets (there are, however, images for some and artist conceptions for the rest...). This is sort of subjective, but among DSOs, I like how the Eye of Sauron of last year, V1647 Ori, has been replaced by a new one.

How do you guys do information on DSOs? When I have time, I actually take notes, but eventually I just run out of time and and copy-paste in relevant webpages.

The event has changed so much this year. Oh my goodness.

I personally use a laptop and ctrl-f. It does mean that I can navigate even when I don't know my notes that well. It also saves trees, I suppose.

Gosh...it's only been a year and the div C astro people suddenly think there's massive changes and don't even know the true eye of sauron?! Eye of sauron is only two things, Fomalhaut and NGC 4151. No exceptions, not V1647 Ori or any other random accreting object or something similar (the Helix Nebula is debatable, but I'd rather not count it). The event really hasn't changed as much as it could've, since the same astronomical techniques and format sticks around.

Also, don't just treat images as direct images. Photometric/spectroscopic data can be/is WAY more important, and is definitely available on the exoplanets (there's various interesting diagrams in general). The only ones I'd say you'd have trouble with finding direct images of would be HD 209458, Kepler 7b, and GJ 1214b, but I know for a fact there's data/diagrams on those. You'll always get objects that are tougher to classify/observe, but that's just to balance ones out that have way too much info on them. At the end of the day there's plenty to find, trust me.

When I was competing (note: last year), I had two methods. One was a "quick cheatsheet" I would make with a bunch of useful fast facts (around a page or two for each DSO). I then had a separate batch of copy/pasted webpages for each DSO, and I also took from google images a ton of images for each DSO. After that I just organized it into my binder, and it worked well. I would read through/highlight major stuff to study, and I was plenty prepared for any DSO section that came my way. Don't be afraid to look at research papers if you're wondering what to study (though, I'm sure you probably know there's plenty to study).

Also, ctrl+f when you don't know where to find stuff is slower than me with my binder when I know where to find stuff . The classic points for both are listed on: http://scioly.org/wiki/index.php/Astron ... _Binder.3F. My partners always used laptops anyway, and I think the combo works nicely.

[DK257]

How do you solve the following type of problem?

Image C1 shows the blackbody spectrum of Star E, which is a main-sequence star with a
parallax of 0.1” and radius of 0.480 Solar Radii. Planet F orbits Star E, has the same mass
and radius as Earth, and lies at a distance of 0.176 AU from Star E. What is the equilibrium temperature of Planet F, in Kelvin, assuming it has 0 albedo?

Do you have to calculate incident radiation and then use the third formula on https://en.wikipedia.org/wiki/Planetary ... emperature? Or is there a more effective (haha) way to do it?

[Schrodingerscat]

How do you solve the following type of problem?

Image C1 shows the blackbody spectrum of Star E, which is a main-sequence star with a
parallax of 0.1” and radius of 0.480 Solar Radii. Planet F orbits Star E, has the same mass
and radius as Earth, and lies at a distance of 0.176 AU from Star E. What is the equilibrium temperature of Planet F, in Kelvin, assuming it has 0 albedo?

Do you have to calculate incident radiation and then use the third formula on https://en.wikipedia.org/wiki/Planetary ... emperature? Or is there a more effective (haha) way to do it?

You can actually use the fourth formula (under theoretical model) more directly once you calculate Star E's temperature from the spectrum, saving you the step of calculating incident radiation.

[cifutielu]

How do you solve for the star's effective temperature?

Image C1 shows the blackbody spectrum of Star E, which is a main-sequence star with a
parallax of 0.1” and radius of 0.480 Solar Radii. Planet F orbits Star E, has the same mass
and radius as Earth, and lies at a distance of 0.176 AU from Star E. What is the equilibrium temperature of Planet F, in Kelvin, assuming it has 0 albedo?

[syo_astro]

How do you solve for the star's effective temperature?

Image C1 shows the blackbody spectrum of Star E, which is a main-sequence star with a
parallax of 0.1” and radius of 0.480 Solar Radii. Planet F orbits Star E, has the same mass
and radius as Earth, and lies at a distance of 0.176 AU from Star E. What is the equilibrium temperature of Planet F, in Kelvin, assuming it has 0 albedo?

Our planet is a blackbody in this case, albedo or a = 0, and we can assume it is heated only by its own star. Thus we apply this model of the planetary equilibrium temperature. This actually comes from equating the energy going into and out of the planet. Moving along from that side note, there's some explanations of how to get to it if you google around, which I hope you do yourself. This problem comes from the AAVSO test posted, and I would say it's definitely a good idea to understand the stuff on that test (and more of course, but that at least).

You should note in the equation the circle with the dot at its center represents the star that the planet goes around (technically it's the symbol for the Sun, though). They give a blackbody spectrum, and by using Wien's law and the maximum emitted wavelength you can derive the effective temperature of the star. Radius of the star and orbital distance are given, so really it's just about converting to consistent units to appropriately solve (to get Kelvin you should note that the temperature should be in Kelvin and then the distances should just be of the same unit). After that you just plug it into the formula, which I hope you understand . Any questions?

[DK257]

How do you solve the following type of problem?

Image C1 shows the blackbody spectrum of Star E, which is a main-sequence star with a
parallax of 0.1” and radius of 0.480 Solar Radii. Planet F orbits Star E, has the same mass
and radius as Earth, and lies at a distance of 0.176 AU from Star E. What is the equilibrium temperature of Planet F, in Kelvin, assuming it has 0 albedo?

Do you have to calculate incident radiation and then use the third formula on https://en.wikipedia.org/wiki/Planetary ... emperature? Or is there a more effective (haha) way to do it?

You can actually use the fourth formula (under theoretical model) more directly once you calculate Star E's temperature from the spectrum, saving you the step of calculating incident radiation.

Oh right, we've calculated the star's temperature. Forgot about that...

How do you solve for the star's effective temperature?

Image C1 shows the blackbody spectrum of Star E, which is a main-sequence star with a
parallax of 0.1” and radius of 0.480 Solar Radii. Planet F orbits Star E, has the same mass
and radius as Earth, and lies at a distance of 0.176 AU from Star E. What is the equilibrium temperature of Planet F, in Kelvin, assuming it has 0 albedo?

Our planet is a blackbody in this case, albedo or a = 0, and we can assume it is heated only by its own star. Thus we apply this model of the planetary equilibrium temperature. This actually comes from equating the energy going into and out of the planet. Moving along from that side note, there's some explanations of how to get to it if you google around, which I hope you do yourself. This problem comes from the AAVSO test posted, and I would say it's definitely a good idea to understand the stuff on that test (and more of course, but that at least).

You should note in the equation the circle with the dot at its center represents the star that the planet goes around (technically it's the symbol for the Sun, though). They give a blackbody spectrum, and by using Wien's law and the maximum emitted wavelength you can derive the effective temperature of the star. Radius of the star and orbital distance are given, so really it's just about converting to consistent units to appropriately solve (to get Kelvin you should note that the temperature should be in Kelvin and then the distances should just be of the same unit). After that you just plug it into the formula, which I hope you understand . Any questions?

Yeah I read the derivation of the formula and it makes sense . I didn't realize that we had already solved for the temperature of the star (simple Wien's law as you said)...

Thanks!

[cifutielu]

How do you solve for the star's effective temperature?

Image C1 shows the blackbody spectrum of Star E, which is a main-sequence star with a
parallax of 0.1” and radius of 0.480 Solar Radii. Planet F orbits Star E, has the same mass
and radius as Earth, and lies at a distance of 0.176 AU from Star E. What is the equilibrium temperature of Planet F, in Kelvin, assuming it has 0 albedo?

Our planet is a blackbody in this case, albedo or a = 0, and we can assume it is heated only by its own star. Thus we apply this model of the planetary equilibrium temperature. This actually comes from equating the energy going into and out of the planet. Moving along from that side note, there's some explanations of how to get to it if you google around, which I hope you do yourself. This problem comes from the AAVSO test posted, and I would say it's definitely a good idea to understand the stuff on that test (and more of course, but that at least).

You should note in the equation the circle with the dot at its center represents the star that the planet goes around (technically it's the symbol for the Sun, though). They give a blackbody spectrum, and by using Wien's law and the maximum emitted wavelength you can derive the effective temperature of the star. Radius of the star and orbital distance are given, so really it's just about converting to consistent units to appropriately solve (to get Kelvin you should note that the temperature should be in Kelvin and then the distances should just be of the same unit). After that you just plug it into the formula, which I hope you understand . Any questions?

Thanks so much for the help! I just have one, quick question.

What units do I need for the radius of the star and the distance to the star when I use them in the theoretical model?

[DK257]

It doesn't actually matter as long as they are in the same units. So typically they'll both be in km or m.

[cifutielu]

For part e of that question, it asks us to use the phase diagram for water along with the temperature to determine if the planet is habitable. How can I use the phase diagram for water to help determine the planet's habitability? I'm not exactly sure how I can use the diagram to my advantage.