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In the 1960s, Penzias and Wilson discovered
a uniform cosmic background radiation
(CMB) in the microwave region of the
electromagnetic spectrum. Explain how the
CMB is consistent with the Big Bang model.
Becrux is a main sequence star and is one of the stars that
make up the Southern Cross. The following data are
available for Becrux.
Apparent magnitude
= 1.25
Absolute magnitude
= –3.92
Apparent brightness
= 7.00 × 10–12 bSun
bSun is the apparent brightness of the Sun. Use the data to
find the distance of Becrux from Earth.
The wavelength of the Lyman-alpha line in the hydrogen
spectrum is measured in the laboratory to be 122 nm. In
the hydrogen spectrum of a galaxy, the Lyman-alpha line
is measured to be 147 nm. Determine the distance of
this galaxy from the Earth. Assume that the Hubble
constant H0 is 75km s–1 M pc–1.
State what is meant by the
(i) Chandrasekhar limit.
(ii) Oppenheimer–Volkoff limit.
Some data for the variable star Betelgeuse are given below.
Average absolute magnitude
= –5.1
Average apparent magnitude
= + 0.60
Average apparent brightness
= 1.6 × 10–7 W m–2
Radius = 790 solar radii
The luminosity of the Sun is 3.8 × 1026 W and it has a
surface temperature of 5700 K. Determine the distance
from Earth to Betelgeuse.
Many galaxies are a great distance from
Earth. Explain, with reference to Hubble’s
law, how the measurement of the red-shift
of light from such galaxies enables their
distance from Earth to be determined.
Some data for the variable star Betelgeuse are given below.
Average absolute magnitude
= –5.1
Average apparent magnitude
= + 0.60
Average apparent brightness
= 1.6 × 10–7 W m–2
Radius = 790 solar radii
The luminosity of the Sun is 3.8 × 1026 W and it has a
surface temperature of 5700 K. The distance from Earth to
Betelgeuse is about 4.0 × 1018 m. Determine, in terms of
the luminosity of the Sun, the luminosity of Betelgeuse.
State one problem associated with using
Hubble’s law to determine the distance of a
galaxy a great distance from Earth.
Four of the planets in the solar system are Mars, Venus,
Jupiter and Neptune.
Some data for the variable star Betelgeuse are given below.
Average absolute magnitude
= –5.1
Average apparent magnitude
= + 0.60
Average apparent brightness
= 1.6 × 10–7 W m–2
Radius
= 790 solar radii
The luminosity of the Sun is 3.8 × 1026 W and it has a
surface temperature of 5700 K. The distance from Earth to
Betelgeuse is about 4.0 × 1018 m. The luminosity of
Betelgeuse is 8.4 x 104 Ls. Calculate the surface
temperature of Betelgeuse.
Some data for the variable star Betelgeuse are given below.
Average absolute magnitude = –5.1
Average apparent magnitude = + 0.60
Average apparent brightness = 1.6 × 10–7 W m–2
Radius
= 790 solar radii
The luminosity of the Sun is 3.8 × 1026 W and it has a surface temperature of 5700
K. The distance from Earth to Betelgeuse is about 4.0 × 1018 m. The luminosity of
Betelgeuse is 8.4 x 104 . The surface temperature of Betelgeuse is 3500 K.
On the Hertzsprung–Russell diagram below
(i) label the position of Betelgeuse with the letter B.
(ii) sketch Betelgeuse’s likely evolutionary path.
One estimate of the Hubble constant is 60 km s–1
Mpc–1. Cygnus A is a radio galaxy at a distance of 6.0
× 108 ly from Earth. Calculate, in km s–1, the
recessional speed of Cygnus A relative to the Earth.
The mass–luminosity relation for main sequence
stars is assumed to be L M3.5, where L is the
luminosity and M is the mass. Star X is 8 × 104
times more luminous than the Sun and 25 times
more massive than the Sun. Deduce that star X is
a main sequence star.
Hubble’s law states that v =H0d, where v is the relative
recessional speed between galaxies, d is their
separation and H0 is the Hubble constant.
Recent measurements place the value of H0 in the
range 60 to 90 km s–1 Mpc–1. Estimate, in seconds, the
maximum known age of the universe.
Hubble’s law states that v =H0d, where v is the relative
recessional speed between galaxies, d is their
separation and H0 is the Hubble constant.
Recent measurements place the value of H0 in the
range 60 to 90 km s–1 Mpc–1. Suggest why a precise
value of H0 is not known.