1
1 mark
1 markWhich of the following describes a standard candle?
a star of known distance
a star of known intensity
a star of known luminosity
a star of known mass
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Astronomy
11 mark
1 markSirius and α-Centauri are two of our closest stars. Sirius has a luminosity about 16 times greater than the luminosity of α-Centauri. Sirius is twice as far away from the Earth as α-Centauri.
The intensity of light from Sirius is Is and the intensity of light from α-Centauri is Iα .
Which of the following is the value of 
?
4
8
16
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21 mark
1 markThe letters W, X, Y and Z represent stars at these positions on the diagram.
Which of the following is part of a possible evolutionary path of a star?
W → Y
X → Y
Y → W
Y → Z
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31 mark
1 markWhich of the following statements about stars in positions W, X, Y and Z is correct?
W and Y have the same mass.
W has a lower surface temperature than Z.
Y is more massive than W.
Y has a lower surface temperature than X.
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41 mark
1 markTau Ceti is one of the closest stars to the Sun. Tau Ceti has a surface temperature of 5300 K and a luminosity of 0.55 LSun, where LSun is the luminosity of the Sun.
Which of the following is the correct description of Tau Ceti?
main sequence star
red dwarf star
red giant star
white dwarf star
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51 mark
1 markTwo stars, P and Q, have approximately the same radius. The surface temperature of star P is twice the surface temperature of star Q.
Star P has a luminosity 
and star Q has a luminosity 
.
The ratio 
is approximately
2
4
8
16
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