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LECTURE 16, OCTOBER 26, 2010

ASTR 101, SECTION 3INSTRUCTOR, JACK BRANDT

jcbrandt@unm.edu

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Question 4

A star’s proper motion is its

a) true motion in space.b) apparent shift as we view from opposite sides of

Earth’s orbit every six months.c) annual apparent motion across the sky.d) motion toward or away from us, revealed by

Doppler shifts.e) orbital motion around the galaxy.

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Question 4

A star’s proper motion is its

a) true motion in space.b) apparent shift as we view from opposite sides of

Earth’s orbit every six months.c) annual apparent motion across the sky.d) motion toward or away from us, revealed by

Doppler shifts.e) orbital motion around the galaxy.

A star’s “real space motion” combines its apparent proper motion with its radial motion toward or away from Earth.

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Question 8

Which of the following quantities do you need in order to calculate a star’s luminosity?

a) apparent brightness (flux)b) Doppler shift of spectral linesc) color of the stard) distance to the stare) a and d

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Question 8

a) apparent brightness (flux)b) Doppler shift of spectral linesc) color of the stard) distance to the stare) a and d

Which of the following quantities do you need in order to calculate a star’s luminosity?

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Question 5

In the stellar magnitude system invented by Hipparchus, a smaller magnitude indicates a _____ star.

a) brighterb) hotterc) coolerd) faintere) more distant

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Question 5

In the stellar magnitude system invented by Hipparchus, a smaller magnitude indicates a _____ star.

a) brighterb) hotterc) coolerd) faintere) more distant

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Question 7

The absolute magnitude of a star is its brightness as seen from a distance of

a) one million km.b) one Astronomical Unit.c) one light-year.d) ten parsecs.e) ten light-years.

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Question 7

The absolute magnitude of a star is its brightness as seen from a distance of

a) one million km.b) one Astronomical Unit.c) one light-year.d) ten parsecs.e) ten light-years.

Astronomers use a distance of 10 parsecs (about 32 light-years) as a standard for specifying and comparing the

brightnesses of stars.

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Question 12

Which spectral classification type corresponds to a star like the Sun?

a) Ob) Ac) Fd) Ge) M

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Question 12a) Ob) Ac) Fd) Ge) M

The OBAFGKM classification scheme is based on absorption lines.

Which spectral classification type corresponds to a star like the Sun?

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Question 9

What are the two most important intrinsic properties for classifying stars?

a) distance and surface temperatureb) luminosity and surface temperature c) distance and luminosityd) mass and agee) distance and color

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Question 9

What are the two most important intrinsic properties for classifying stars?

a) distance and surface temperatureb) luminosity and surface temperature c) distance and luminosityd) mass and agee) distance and color

The H–R diagram plots stars based on their luminosities and surface

temperatures.

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Question 15

Eclipsing binary stars are very useful for determining the

a) ages of stars.b) absolute luminosities of stars.c) masses of stars.d) distances to stars.e) rotation rates of stars.

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Question 15

Eclipsing binary stars are very useful for determining the

a) ages of stars.b) absolute luminosities of stars.c) masses of stars.d) distances to stars.e) rotation rates of stars.

Analysis of the lightcurve of an eclipsing binary star system can reveal the masses of the stars.

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