## Astronomy C

sciolyPA
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### Re: Astronomy C

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?)

Unome
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### Re: Astronomy C

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$LaTeX code$
Schwarzschild radius = $\frac{2GM}{c^2}$
The Sun's mass is approximately $1.9*10^30 kg$, $G = 6.67*10^{-11}$ in SI units, and $c = 3*10^8 m/s$.
Therefore $R = 8.45 km$
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sciolyPA
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### Re: Astronomy C

Code: Select all

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

Code: Select all

$LaTeX code$
Schwarzschild radius = $\frac{2GM}{c^2}$
The Sun's mass is approximately $1.9*10^30 kg$, $G = 6.67*10^{-11}$ in SI units, and $c = 3*10^8 m/s$.
Therefore $R = 8.45 km$

Looks good and thanks for the help!

Unome
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### Re: Astronomy C

Image
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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PM2017
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### Re: Astronomy C

Image
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...)
West High '19
UC Berkeley '23

Go Bears!

sciolyPA
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Posts: 13
Joined: February 15th, 2018, 6:29 pm
Division: C
State: PA

### Re: Astronomy C

Image
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?
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
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State: CA

### Re: Astronomy C

I'm actually clueless as to which DSO this is...
Image
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?
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?
West High '19
UC Berkeley '23

Go Bears!

sciolyPA
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Posts: 13
Joined: February 15th, 2018, 6:29 pm
Division: C
State: PA

### Re: Astronomy C

I'm actually clueless as to which DSO this is...
Image
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?
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
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Location: Carnegie Mellon University

### Re: Astronomy C

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
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Division: C
State: PA

### Re: Astronomy C

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.