ASTR HW 5 (Lecture 6)

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Before starting these questions, please watch Lecture 6. You must submit them at one time. The submit button is at the bottom. Please only submit once.

A star that has an absolute magnitude of -10 is *

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much brighter than a star with an absolute magnitude of +10.

much dimmer than a star with an absolute magnitude of +10.

just as bright as a star with an absolute magnitude of +10.

necessarily going to look very bright in the night sky.

Stellar parallax (please select all true statements) *

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cannot determine distances to stars on the other side of the galaxy.

can determine distances to stars on the other side of the galaxy.

is, in principle, more accurate for very small parallax angles.

is, in principle, less accurate for very small parallax angles.

Required

Our Sun *

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is an F-type star, and therefore has strong neutral and ionized metal lines.

is a G-type star, and therefore has strong neutral and ionized metal lines.

is a G-type star, and therefore has strong neutral but no ionized metal lines.

is a G-type star--and, since it therefore has no helium lines, it does not have helium.

Stellar spectra (please select all true statements) *

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are of the emission type.

allow us to determine the elemental composition of the surfaces and atmospheres of stars.

allow us to determine the temperatures of the surfaces of stars.

are of the absorption type.

are a set of equations that describe the fusion reactions of stars.

are of the continuous type.

Required

If you are twice as far away than I am from the Sun, (please select all true statements) *

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you will receive 25% of the amount of sunlight that I receive.

you will receive 50% of the amount of sunlight that I receive.

you will receive 25% more sunlight than I receive.

the Sun will appear to be 25% as bright to you compared to me.

the Sun will appear to be 50% as bright to you compared to me.

Required

A star with a parallax angle of 3 arcseconds is *

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closer than a star with a parallax angle of 4 arcseconds.

closer than a star with a parallax angle of 2 arcseconds.

the same distance as a star with a parallax angle of 4 arcseconds.

on the other side of our galaxy.

⏩ FORM_TIMER_UNIQUE_IDENTIFIER *

Please write your initials here.

Apparent brightness *

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obeys an inverse square law, since the surface area of a ball is 4π times the square of its radius.

obeys an inverse cube law, since the volume of a ball is 4π/3 times the cube of its radius.

obeys a linear law.

is identical to absolute brightness.

A star has a Planck blackbody peak at a wavelength of 400 nm, as measured by an observer next to the star. If this star is moving away from us, *

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we will measure its peak to be at a wavelength that is less than 400 nm.

we will measure its peak to be at a wavelength that is greater than 400 nm.

we will measure its peak to be at a wavelength of 400 nm.

One cannot determine the answer to this question from the information given.

Required

The brightest (most luminous) stars are *

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the largest and hottest stars.

largest and coolest stars.

G-type stars.

the closest stars.

The hottest stars *

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are made mostly hydrogen, despite the fact that their hydrogren lines are weak.

have almost no hydrogen, since their hydrogren lines are weak.

have strong metal lines.

have strong metal and hydrogen lines.

have strong hydrogen lines.

A star that emits a vast amount of light will *

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appear very bright in the night sky, regardless of how far away the star is.

appear very bright in the night sky, since the brightest stars in the night sky are necessarily the ones that emit the most light.

appear very dim in the night sky if the star is very fall away.

aways be a M-type star.

aways be a B-type star.

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