Auriga the Charioteer - Northern Hemisphere
A striking
constellation in the northern skies, Auriga lies above the horns of
Taurus the Bull and forms the shape of a kite. Auriga is named after
the son of Vulcan who invented the four horse chariot. Its brightest
star Capella is the 6th brightest star in the sky.
In 1899 astronomers
discovered that Capella was not a single star but a double star. Like
so many stars that appear single to the eye, Capella actually
consists of two stars. But there's more going on with Capella as
there is another component to this system, a pair of small red stars,
meaning that where we see just one star there are actually 6!!
Capella whose name
means the ‘Little She Goat’ has a magnitude of 0.1 and its a
class G3 giant slightly cooler than our Sun which is a G2 dwarf and
is 43 light years distant.
In brightness it is
virtually equal to Vega in the constellation of Lyra the Lyre but it
is of a very different colour, its yellowish tinge contrast sharply
with the steely blue of Vega. Both are circumpolar from Britain, they
can be seen all year round. They lie on opposite sides of the north
pole star and at roughly the same distance from it. This mean that
when Capella is high up Vega is low down and vice versa. From Britain
Capella is overhead during winter evenings while in summer it is Vega
that occupies that position. When at their lowest they are very low
just above the horizon.
Slightly to the
right and just below Capella is a little but quite distinct triangle
of stars called the Haedi or the kids. They are referred to as the
Kids because where the she goat goes the kids will always follow!!
The top star in the triangle is epsilon, bottom left star is eta and
the bottom right is zeta.
Epsilon is a F0
supergiant white star its distance in not known with any great
certainty but it could be about 2,000 light years away. It normally
it shines at around magnitude 3.0 but every 27 years it fades to
magnitude 3.8 where it remains for between 640–730 days – about
two years. Epsilon is eclipsed by an unseen and unknown very large
companion star. The star’s last dimming was from 2009 to 2011.
The next should begin around 2038!
Zeta is another
eclipsing binary where the companion star cannot be seen with the
naked eye and varies between magnitude 3.7-4.1 over a period of 972
days. Zeta is a K5 class giant star lying 790 light years away.
The third component
eta which is 243 light years away. It is a B3 class star making it
much hotter than the Sun, and has a brightness of magnitude 3.2.
Beta or Menkalinan
which means ‘Shoulder of the Charioteer’, is the second brightest
star in Auriga and is found to the left of Capella with a magnitude
of 2.0 the same brightness as the North Star. It is an A1 class star
with a surface temperature of around 9,000` C much hotter than our
Sun. It lies at a distance of 82 light years.
A line drawn down
from beta will reach the star theta or Mahasin with means the ‘Wrist
of the Charioteer’. Theta has a magnitude of 2.6, and is an A class
star 166 light years away.
From eta which is
the top star of the Haedi or kids a line drawn down and past zeta
will come across iota or Al Kab which means the ‘Shoulder of the
Rein holder’ at a distance of 490 light years we see iota as a star
of magnitude 2.7. It is a K3 giant being cooler than our Sun.
In 1930 for some
reason the star that was originally classified as gamma Aurigae was
transferred to the constellation of Taurus the Bull and re labelled
at beta Tauri. It makes no sense at all as it is the bottom of the
kite shape which used to form Auriga.
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