Astronomy C

[Adi1008]

Correct. Your turn.

Btw, if you're curious about how exoplanetology as a whole has influenced the core-accretion theory, check out this article: http://www.nature.com/news/astronomy-pl ... os-1.15480

Thanks for the article AlphaTauri. Looks like an interesting read.

What are pre-main sequence stars with less mass than a Herbig Ae/Be star called? What are they powered by instead of hydrogen fusion (because they are too small)?

They are (Click to Show Hidden Text)

T Tauri stars, powered by the gravity of falling gas. As a small core forms from a molecular cloud, the gas 'falls' into the T Tauri, generating heat energy from gravitational potential energy.

Correct. Your turn.

[Magikarpmaster629]

The apparent position of star A from Earth is measured in March, and then again 6 months later in September. If the apparent position of star A changed by 0.036 arcseconds, what is the approximate distance from the sun to star A in lightyears?

[Adi1008]

The apparent position of star A from Earth is measured in March, and then again 6 months later in September. If the apparent position of star A changed by 0.036 arcseconds, what is the approximate distance from the sun to star A in lightyears?

._. (Click to Show Hidden Text)

d (in parsecs) = 1/p (in arcseconds).  p = 0.036 arcseconds. Substituting this in, we get ~27.77 parsecs. Multiply by 3.26 to get LY, giving us [b]90.55 LY[/b]. Do we need to worry about sig figs in astro?

[Magikarpmaster629]

The apparent position of star A from Earth is measured in March, and then again 6 months later in September. If the apparent position of star A changed by 0.036 arcseconds, what is the approximate distance from the sun to star A in lightyears?

._. (Click to Show Hidden Text)

d (in parsecs) = 1/p (in arcseconds).  p = 0.036 arcseconds. Substituting this in, we get ~27.77 parsecs. Multiply by 3.26 to get LY, giving us [b]90.55 LY[/b]. Do we need to worry about sig figs in astro?

I was too lazy to come up with a good question, your turn

[Adi1008]

The apparent position of star A from Earth is measured in March, and then again 6 months later in September. If the apparent position of star A changed by 0.036 arcseconds, what is the approximate distance from the sun to star A in lightyears?

._. (Click to Show Hidden Text)

d (in parsecs) = 1/p (in arcseconds).  p = 0.036 arcseconds. Substituting this in, we get ~27.77 parsecs. Multiply by 3.26 to get LY, giving us [b]90.55 LY[/b]. Do we need to worry about sig figs in astro?

I was too lazy to come up with a good question, your turn

Suppose a person is looking at two stars, A and B, and perceives A to be 10 times brighter than B. The product of the magnitudes of the stars is 9, and both magnitudes are positive. What are the magnitudes of both stars?

[Skink]

The apparent position of star A from Earth is measured in March, and then again 6 months later in September. If the apparent position of star A changed by 0.036 arcseconds, what is the approximate distance from the sun to star A in lightyears?

._. (Click to Show Hidden Text)

d (in parsecs) = 1/p (in arcseconds).  p = 0.036 arcseconds. Substituting this in, we get ~27.77 parsecs. Multiply by 3.26 to get LY, giving us [b]90.55 LY[/b]. Do we need to worry about sig figs in astro?

Mhm, C Division has a blanket sig figs policy. Whether it's enforced is another story.

[Adi1008]

The apparent position of star A from Earth is measured in March, and then again 6 months later in September. If the apparent position of star A changed by 0.036 arcseconds, what is the approximate distance from the sun to star A in lightyears?

._. (Click to Show Hidden Text)

d (in parsecs) = 1/p (in arcseconds).  p = 0.036 arcseconds. Substituting this in, we get ~27.77 parsecs. Multiply by 3.26 to get LY, giving us [b]90.55 LY[/b]. Do we need to worry about sig figs in astro?

Mhm, C Division has a blanket sig figs policy. Whether it's enforced is another story.

Thanks Skink. Guess my answer should have been this:

._. (Click to Show Hidden Text)

d (in parsecs) = 1/p (in arcseconds).  p = 0.036 arcseconds. Substituting this in, we get ~27.77 parsecs, [b]but 0.036 has 2 sig figs so 28[/b].Multiply by 3.26 to get LY and round to 2 sig figs, giving us [b]91 LY[/b].

[finagle29]

Suppose a person is looking at two stars, A and B, and perceives A to be 10 times brighter than B. The product of the magnitudes of the stars is 9, and both magnitudes are positive. What are the magnitudes of both stars?

Assuming the product of the [i]apparent[/i] magnitudes of the stars is 9, the magnitudes of the stars are (Click to Show Hidden Text)

A: 2, B: 4.5
From the equation for apparent magnitude [math]m_a - m_b = -2.5 \log_{10}\left(\frac{I_a}{I_b}\right)[/math] we see that [math]m_a - m_b = -2.5[/math] (because the common log of 10 is just 1) and since we're given [math]m_am_b=9[/math], algebra tells us that there are two solutions [math](m_a,m_b)=\pm(2,4.5)[/math] only one of which is positive.

[Adi1008]

Suppose a person is looking at two stars, A and B, and perceives A to be 10 times brighter than B. The product of the magnitudes of the stars is 9, and both magnitudes are positive. What are the magnitudes of both stars?

Assuming the product of the [i]apparent[/i] magnitudes of the stars is 9, the magnitudes of the stars are (Click to Show Hidden Text)

A: 2, B: 4.5
From the equation for apparent magnitude [math]m_a - m_b = -2.5 \log_{10}\left(\frac{I_a}{I_b}\right)[/math] we see that [math]m_a - m_b = -2.5[/math] (because the common log of 10 is just 1) and since we're given [math]m_am_b=9[/math], algebra tells us that there are two solutions [math](m_a,m_b)=\pm(2,4.5)[/math] only one of which is positive.

That's a good point. I forgot to specify in the question that I was talking about apparent magnitude. Sorry for any confusion. Also, how did you LaTeX the math in your answer?

The answer you got was right, so your turn now.

[finagle29]

Code: Select all

[math]LaTeX code here[/math]

Which DSO was the IAU petitioned to be renamed Gallifrey?