Astronomy C

[Tom_MS]

trying (Click to Show Hidden Text)

a. Absolute magnitude of 3, so I assume I'm supposed to look at an H-R diagram since it says main sequence? I get ~9000K.
b. I think Hydrogen lines peak at around this temperature, not entirely sure though.
c. ~18.5 km/sec
d. No idea. Does this have something to do with the size of star necessary to eclipse at a certain orbital distance?

Yeah, I'd say D is unsolvable. To Tom_MS: No offence, but these are pretty badly written questions. While there are charts and relations between luminosity and temperature and mass, typically I see tests avoid having these relations match up because the purpose of the math in this event isn't for the student to look up the answer in a table, but to use real math and solve for variables using Kepler's law, Wien's law, Stefan-Boltzmann law, etc. I'd suggest you look at some of the tests in the test exchange (https://scioly.org/wiki/index.php/2017_ ... #Astronomy) for past questions.

Unome, you should go next.

Alright. I intended for you to notice that it is about an A type star, so there are those spectral features characteristic of those stars. The idea with D was that there is the main-sequence mass-luminosity relation. I realized that this relation wasn't consistent across all sources, but I figured that if work was shown, it would be a creative way to solve for the separation of the system and therefore the angular diameter.

[Magikarpmaster629]

Starting this up again:

Star C and Supernova A have the same apparent magnitude. Supernova A is a type Ia and is located in a galaxy 15 Mpcs distant. Assume all type Ia supernovae are all the same brightness, with an absolute magnitude of -19.3.

a) What is the recessional velocity of the galaxy in which Supernova A is located? Answer in m/s.
b) Type Ia supernovae have strong silicon lines. One Si II line from Supernova A has an apparent wavelength of 126.94 nm. What was its emitted wavelength in nm?
c) What is the apparent magnitude of Star C?
d) What is the distance to Star C in parsecs?

[jonboyage]

Starting this up again:

Star C and Supernova A have the same apparent magnitude. Supernova A is a type Ia and is located in a galaxy 15 Mpcs distant. Assume all type Ia supernovae are all the same brightness, with an absolute magnitude of -19.3.

a) What is the recessional velocity of the galaxy in which Supernova A is located? Answer in m/s.
b) Type Ia supernovae have strong silicon lines. One Si II line from Supernova A has an apparent wavelength of 126.94 nm. What was its emitted wavelength in nm?
c) What is the apparent magnitude of Star C?
d) What is the distance to Star C in parsecs?

Answer (Click to Show Hidden Text)

a) 1,050,000 m/s
b) ~126.50nm
c) ~11.58
d) missing information :(

[Magikarpmaster629]

Starting this up again:

Star C and Supernova A have the same apparent magnitude. Supernova A is a type Ia and is located in a galaxy 15 Mpcs distant. Assume all type Ia supernovae are all the same brightness, with an absolute magnitude of -19.3.

a) What is the recessional velocity of the galaxy in which Supernova A is located? Answer in m/s.
b) Type Ia supernovae have strong silicon lines. One Si II line from Supernova A has an apparent wavelength of 126.94 nm. What was its emitted wavelength in nm?
c) What is the apparent magnitude of Star C?
d) What is the distance to Star C in parsecs?

Answer (Click to Show Hidden Text)

a) 1,050,000 m/s
b) ~126.50nm
c) ~11.58
d) missing information :(

Oh whoops, I wrote these questions for my event partner and I took out some info. (d) should read:
The observed flux from Star C is measured to be 6.04*10^-13 W/m^2. If the luminosity of Star C is 0.286 solar luminosities, What is the distance to Star C in parsecs? Calculate using the Stefan Boltzmann Law. (You could just use distance mod, it's the same thing, but my partner needed some SB practice)
Answer is~123 parsecs Your turn!

[jonboyage]

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
-3.6789 solar radii
-35mas

[Magikarpmaster629]

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
-3.6789 solar radii
-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.

[jonboyage]

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
-3.6789 solar radii
-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!

[Magikarpmaster629]

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?

[Magikarpmaster629]

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

[Unome]

(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).