Astronomy C

[sciolyPA]

Image
1. What DSO was this data gathered from?
2. Is this image a spectrum, light curve, or radial velocity graph? (meta question to anyone who can answer - what would be a good way to phrase this without listing options?)
3. What orbital phenomenon does this image show?
4. How many times brighter is the star at peak brightness than at minimum?

Answer (Click to Show Hidden Text)

1. HR 5171 A
2.light curve
3.It shows two stars in a binary system eclipsing each other, which accounts for the changing magnitude.
4.Is it 1.2 times brighter?

[PM2017]

I'm actually clueless as to which DSO this is...

Image
1. What DSO was this data gathered from?
2. Is this image a spectrum, light curve, or radial velocity graph? (meta question to anyone who can answer - what would be a good way to phrase this without listing options?)
3. What orbital phenomenon does this image show?
4. How many times brighter is the star at peak brightness than at minimum?

Answer (Click to Show Hidden Text)

1. HR 5171 A
2.light curve
3.It shows two stars in a binary system eclipsing each other, which accounts for the changing magnitude.
4.Is it 1.2 times brighter?

I'm actually stupid... HR 5171 A is the only binary of the type that fits with the light curve given this year...
EDIT: Wait, but doesn't the magnitude not match?

[sciolyPA]

I'm actually clueless as to which DSO this is...

Image
1. What DSO was this data gathered from?
2. Is this image a spectrum, light curve, or radial velocity graph? (meta question to anyone who can answer - what would be a good way to phrase this without listing options?)
3. What orbital phenomenon does this image show?
4. How many times brighter is the star at peak brightness than at minimum?

Answer (Click to Show Hidden Text)

1. HR 5171 A
2.light curve
3.It shows two stars in a binary system eclipsing each other, which accounts for the changing magnitude.
4.Is it 1.2 times brighter?

I'm actually stupid... HR 5171 A is the only binary of the type that fits with the light curve given this year...
EDIT: Wait, but doesn't the magnitude not match?

At an invitational earlier this year I got the the same graph with the same scale for HR 5171 A, so I hope it's right.

[c0c05w311y]

Unome and everyone really, could you please use image hosting site imgbb instead of imgur or something else so that PM2017, Jonboyage, and I (probably others too) can access the images at school? No need to re-post, just for the future. Thanks

[sciolyPA]

A pulsar has a mass of 2.5E30 kg and a radius of 3E4 m.
a) What is its rotational inertia?
b) If it's initial period is 1.6 s, what is it's rotational kinematic energy?
c) Given that it has a spin down rate of .0006 s/y, find the rate of kinematic loss of the pulsar.

[Adi1008]

A pulsar has a mass of 2.5E30 kg and a radius of 3E4 m.
a) What is its rotational inertia?
b) If it's initial period is 1.6 s, what is it's rotational kinematic energy?
c) Given that it has a spin down rate of .0006 s/y, find the rate of kinematic loss of the pulsar.

Answer (Click to Show Hidden Text)

a)
[math]I = \frac{2}{5}mr^{2} = \frac{2}{5} \times 2.5 \times 10^{30} \times (3 \times 10^{4})^{2} = 9 \times 10^{38} \mathrm{kg \cdot m^{2}}[/math]
b)
[math]E = \frac{1}{2}I\omega^{2} = 6.94 \times 10^{39} \mathrm{J}[/math]
c)
[math]\frac{dE}{dt}=\frac{d}{dt} \bigg( \frac{1}{2}I\omega^2 \bigg) = -\frac{4 I \pi^2}{P^3} \cdot \frac{dP}{dt} = -3.6 \times 10^{-22} \mathrm{J/s}[/math]

[sciolyPA]

A pulsar has a mass of 2.5E30 kg and a radius of 3E4 m.
a) What is its rotational inertia?
b) If it's initial period is 1.6 s, what is it's rotational kinematic energy?
c) Given that it has a spin down rate of .0006 s/y, find the rate of kinematic loss of the pulsar.

Answer (Click to Show Hidden Text)

a)
[math]I = \frac{2}{5}mr^{2} = \frac{2}{5} \times 2.5 \times 10^{30} \times (3 \times 10^{4})^{2} = 9 \times 10^{38} \mathrm{kg \cdot m^{2}}[/math]
b)
[math]E = \frac{1}{2}I\omega^{2} = 6.94 \times 10^{39} \mathrm{J}[/math]
c)
[math]\frac{dE}{dt}=\frac{d}{dt} \bigg( \frac{1}{2}I\omega^2 \bigg) = -\frac{4 I \pi^2}{P^3} \cdot \frac{dP}{dt} = -3.6 \times 10^{-22} \mathrm{J/s}[/math]

Looks good, your turn

[Adi1008]

A pulsar has a mass of 2.5E30 kg and a radius of 3E4 m.
a) What is its rotational inertia?
b) If it's initial period is 1.6 s, what is it's rotational kinematic energy?
c) Given that it has a spin down rate of .0006 s/y, find the rate of kinematic loss of the pulsar.

Answer (Click to Show Hidden Text)

a)
[math]I = \frac{2}{5}mr^{2} = \frac{2}{5} \times 2.5 \times 10^{30} \times (3 \times 10^{4})^{2} = 9 \times 10^{38} \mathrm{kg \cdot m^{2}}[/math]
b)
[math]E = \frac{1}{2}I\omega^{2} = 6.94 \times 10^{39} \mathrm{J}[/math]
c)
[math]\frac{dE}{dt}=\frac{d}{dt} \bigg( \frac{1}{2}I\omega^2 \bigg) = -\frac{4 I \pi^2}{P^3} \cdot \frac{dP}{dt} = -3.6 \times 10^{-22} \mathrm{J/s}[/math]

Looks good, your turn

In the image above:

a) What does the green line represent?
b) What does the light blue line represent?
c) What does the dark blue line represent?
d) The red arrows show evolutionary paths for different pulsars that start at the same location but have different braking indices. Put each evolutionary path (top, middle, and bottom) in order of increasing braking index.
e) The x-axis is on a (linear/logarithmic) scale

[Unome]

Answer (Click to Show Hidden Text)

a)
[math]I = \frac{2}{5}mr^{2} = \frac{2}{5} \times 2.5 \times 10^{30} \times (3 \times 10^{4})^{2} = 9 \times 10^{38} \mathrm{kg \cdot m^{2}}[/math]
b)
[math]E = \frac{1}{2}I\omega^{2} = 6.94 \times 10^{39} \mathrm{J}[/math]
c)
[math]\frac{dE}{dt}=\frac{d}{dt} \bigg( \frac{1}{2}I\omega^2 \bigg) = -\frac{4 I \pi^2}{P^3} \cdot \frac{dP}{dt} = -3.6 \times 10^{-22} \mathrm{J/s}[/math]

Looks good, your turn

In the image above:

a) What does the green line represent?
b) What does the light blue line represent?
c) What does the dark blue line represent?
d) The red arrows show evolutionary paths for different pulsars that start at the same location but have different braking indices. Put each evolutionary path (top, middle, and bottom) in order of increasing braking index.
e) The x-axis is on a (linear/logarithmic) scale

Answers (possibly) (Click to Show Hidden Text)

(a - c) Are definitely going to be lines of equal mass/etc., though I'm not certain what any of them actually are. If this were an actual test, I'd probably put mass for all of them. I think dark blue is most likely to be mass though, 
(d) I'm not sure, but I would assume a larger braking index implies an increasing decrease in period - therefore: top, middle, bottom.
(e) logarithmic

[c0c05w311y]

there's no way I would know this if I hadn't read the paper that this graph came from a few months ago, but the blue lines are constant magnetic field strength since its basically proportional to sqrt(P*Pdot), the green lines are constant characteristic age since thats P/(2*Pdot), and the light blue lines are constant Edot since thats basically proportional to Pdot / P^3 (drawing the lines does use some assumptions)