Short Training Tasks
These short tasks shoult familiarise you with the
different qiantities just introduced
Photo 1: Betelgeuse (Orion – The Hunter) |
Photo 2: Vega (Lyra – The Lyre) |
Photo 3: The Summer Triangle:
(clockwise)
Deneb (Cygnus – The Swan), Vega (Lyra –
The Lyre), Altair (Aquila – The Eagle)
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Photo 4: Sirius (Canis Major - The Greater Dog)
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Task AT1
The star α-Orionis (Betelgeuse) has an apparent
magnitude of m = 0.45 and an absolute magnitude
of M = –5.14.
Find the distance to Betelgeuse. Betelgeuse is the red star at the left shoulder
of Orion (seen from Earth) and is a red
supergiant. When viewed with the naked eye, it
has a clear orange-red hue.
Task AT2α-Lyrae (Vega), with an absolute magnitude of
0.58, is at a distance of 7.76 parsec.
Calculate Vega's apparent magnitude Vega is the brightest star in the constellation of
Lyra (the Lyre) and the upper right star in the
Summer Triangle.
Vega is the brightest star in the constellation of Lyra (the Lyre)
and the upper right star in the Summer Triangle.
Task AT3α-Cygni (Deneb) is the upper left star in the
Summer Triangle and the main star in the Swan.
Its apparent magnitude is 1.25 and the distance
to Deneb is 993 parsec.
Calculate the absolute magnitude. What does this tell you about the nature of Deneb?
Task AT4
The star α-Canis Majoris (Sirius) is the brightest star in the sky. It is at a distance of 2.64 parsecs and its apparent magnitude is –1.44.
Calculate the absolute magnitude of Sirius. If you compare with the absolute magnitudes for the three other stars what is your judgement of Sirius’ physical or intrinsic brightness?
Task AT5
If the stars Vega, Sirius, Betelgeuse and Deneb were located 10 parsecs from the Earth (in the same region of the sky), what would we see?
Task AT6
The absolute magnitude, M, is defined as the apparent magnitude a star would have if it were placed 10 parsecs from the Sun.
But wouldn’t it be more correct to measure this distance from the Earth? Why doesn’t it make a difference whether we measure this distance from the Sun or from the Earth?
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