Astronomy C

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Re: Astronomy C

Postby sciolyPA » February 24th, 2018, 2:43 pm

A star has three times the mass of the sun, what would its schwarzschild radius be? (Also how do you hide your answer behind an answer box and how do you upload math equations to show work?)

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Re: Astronomy C

Postby Unome » February 24th, 2018, 2:49 pm

Code: Select all

[hide]visible text|hidden text[/hide]

Code: Select all

[math]LaTeX code[/math]


Answer
Schwarzschild radius =
The Sun's mass is approximately , in SI units, and .
Therefore
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Re: Astronomy C

Postby sciolyPA » February 24th, 2018, 2:51 pm

Unome wrote:

Code: Select all

[hide]visible text|hidden text[/hide]

Code: Select all

[math]LaTeX code[/math]


Answer
Schwarzschild radius =
The Sun's mass is approximately , in SI units, and .
Therefore



Looks good and thanks for the help!

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Re: Astronomy C

Postby Unome » February 24th, 2018, 4:57 pm

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?
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Re: Astronomy C

Postby PM2017 » February 24th, 2018, 5:58 pm

Unome wrote: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?


an answer to your meta question: You could ask, "What type of chart is shown in this image?"

(also, the sad feel when you can answer all the questions except for the first, and probably easiest one... I'm actually clueless as to which DSO this is...)
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Re: Astronomy C

Postby sciolyPA » February 24th, 2018, 6:59 pm

Unome wrote: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
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?

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Re: Astronomy C

Postby PM2017 » February 24th, 2018, 7:18 pm

PM2017 wrote:I'm actually clueless as to which DSO this is...


sciolyPA wrote:
Unome wrote: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
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?
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Re: Astronomy C

Postby sciolyPA » February 24th, 2018, 7:25 pm

PM2017 wrote:
PM2017 wrote:I'm actually clueless as to which DSO this is...


sciolyPA wrote:
Unome wrote: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
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.

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Re: Astronomy C

Postby c0c05w311y » February 26th, 2018, 1:43 pm

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

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Re: Astronomy C

Postby sciolyPA » February 27th, 2018, 9:30 am

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.

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Re: Astronomy C

Postby Adi1008 » February 27th, 2018, 4:09 pm

sciolyPA wrote: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
a)

b)

c)
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Re: Astronomy C

Postby sciolyPA » February 28th, 2018, 5:51 pm

Adi1008 wrote:
sciolyPA wrote: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
a)

b)

c)



Looks good, your turn

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Re: Astronomy C

Postby Adi1008 » February 28th, 2018, 9:51 pm

sciolyPA wrote:
Adi1008 wrote:
sciolyPA wrote: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
a)

b)

c)



Looks good, your turn

Image

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
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Re: Astronomy C

Postby Unome » March 1st, 2018, 6:22 am

Adi1008 wrote:
sciolyPA wrote:
Adi1008 wrote:
Answer
a)

b)

c)



Looks good, your turn

Image

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)
(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
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Re: Astronomy C

Postby c0c05w311y » March 1st, 2018, 12:54 pm

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)


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