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Is Taurus attacking Orion, the Hunter, or are
the Horns of the Bull the real story?
The horn was a symbol of fertility and bountiful riches in many cultures
for thousands of years, and it is probably the case here, for the
constellation would have announced the Vernal Equinox at around 4000 BC.
The constellation Taurus may also allude to the Greek story of Europa and
the Bull. Europa was daughter of King Agenor. One fine spring day,
accompanied by her hand maidens, Princess Europa went to the seashore to
gather flowers. Zeus, who had fallen in love with Europa, seized the
opportunity.
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Zeus transformed himself into a magnificent white bull, and as such he
joined King Agenor's grazing herd. Europa noticed the wonderful white
beast, who gazed at them all with such a mild manner that they were not
frightened.
Europa wove wreathes of flowers for the beast, and wrapped them around
his horns. She led him around the meadow, and he was as docile as a lamb.
Then, as he trotted down to the seashore, she jumped onto his shoulders.
Suddenly, to her surprise and fright, he plunged into the sea and carried
the princess to Crete.
As they reached the Cretan shore, Zeus then turned into an eagle and
ravaged Europa. She bore three sons, the first of which was Minos.
Minos is said to have introduced the bull cult to the Cretans. He had
Daedalus build a labyrinth in the depths of his palace at Knossus, which
became the home of the Minotaur (offspring of Mino's wife Pasiphae, and
a bull). Seven young men and seven maidens were ritually sacrificed to
the Minotaur until Theseus killed it.
Minos, in fact, was the title of the ancient rulers of Crete, and the
story probably tells of their mythic origin.
The constellation shows mainly the horns, and exceedingly long horns
they are. The left (southern) horn starts from the group of stars known
as The Hyades, of which Aldebaran seems (erroneously) to be a member.
It extends from Aldebaran to zeta Tauri, near the eastern edge of the
constellation.
The right horn lifts up just west of the Hyades, from delta Tauri
through tau Tauri and finally to its tip at beta Tauri (El Nath:
remember this star as part of Auriga?)
The rest of the bull is rather disappointing; a slight body and two
spindly legs. It may be that the bull is half-emerged in water, as it
carries Europa across to Crete.
The stars of Taurus:
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Taurus' eye is bright and piercing. This is Aldebaran (alpha Tauri),
an orange giant about 40 times the size of the Sun. Aldebaran is an old
star. For billions of years it has burned its supply of hydrogen until
there is little left. Its future won't be as a spectacular explosion of
a supernova but rather a gradual dimming into a white dwarf.
Following the lower horn out to its tip we find zeta Tauri. This is a
shell star. Shell stars are main-sequence stars which rotate rapidly,
causing a loss of matter to an ever-expanding shell.
Most of the interesting features of Taurus are found in the centre of
the constellation and toward the west. Around Aldebaran are a number of stars
which go by the collective name of The Hyades (see below).
Aldebaran is not a member of this group. Not only is it closer to us, but
its proper motion is at a different angle. Aldebaran is moving at an angle
of 161 degrees, the stars of the Hyades at around 102-109 degrees.
Double stars in Taurus
Taurus has an abundant selection of binary stars, including many Struve
binaries that we haven't mentioned. Below is a very small selection of
some of the easier doubles to resolve.
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Theta2 and theta1 form a fixed binary
of wide separation, theta2 just below and to the east. Note that theta2 is the primary: 3.4, 3.8; PA 346º and separation 337".
Kappa1 and kappa1 form an easily
resolved binary: 4.2, 5.3; PA 328º, separation 5.3".
Sigma2 and sigma1 is another wide
fixed binary. And again, sigma2 is the primary: 4.8, 5.2; PA 193º and separation 431".
80 Tauri is a difficult visual binary with an
orbit of 189.5 years: 5.5, 8.0; current PA 17º
and separation of 1.8" (very nearly its maximum separation).
Struve 422 is a wide visual binary with an orbit of over 2000 years: 5.9, 8.8; PA 269º, 6.7". It's located at 9º SW of nu Tauri, just north of the brighter 10 Tauri.
Variable stars in Taurus
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Many of the more notable variable stars in Taurus are of a type not noticed
by casual observation, such as alpha Taurus, which is classified
as an Lb type variable. These are irregular giants whose variation can only
be detected by means of photoelectric photometry. Alpha Taurus only
changes in visual magnitude by 0.2, from 0.75 to 0.95, and the period is
irregular.
BU Tauri (Pleione) is a gammaCas type variable, from 4.77 to 5.50.
GammaCas variables are also characterised by an irregular period, which
may sometimes be very rapid. These are B stars, quite young, and rotate
very rapidly. This rotation results in the throwing off of material,
which then forms a shell around the star. The cause of its variation is
still not understood.
Zeta Tauri is also a gammaCas type variable, with a variation
from 2.88 down to 3.17 roughly every 133 days.
Lambda Tauri, in the Hyades cluster, is a good example of an eclipsing
variable. The variability is caused by the partial eclipse of the primary
by its companion, dimming the 3.3 visual magnitude down to 3.8 every
3.95 days.
R Tauri is a Mira-type variable with a 320.9 day period. Usually at
7.6, it drops to a very dim 15.8 once a year. In 2000 the maximum should
occur in the first week of May.
Deep Sky Objects in Taurus:
Taurus contains two well known Messier objects: the Crab Nebula and the
Pleiades. Besides these two there is the `other' cluster, known as The
Hyades, and the curious "Hind's Variable Nebula".
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Just northwest of zeta Tauri is the first of Messier's objects: M1,
the Crab Nebula. Early observers thought the object to be a star
cluster, something like a dimmer version of the Great Orion Nebula. Messier
was so intrigued by it, on the night of 12 September, 1758, that he began
his catalogue - the purpose of which was to keep observers from mistaking
such objects for comets.
It takes a rather large telescope to see any of the filamentary features of
the nebula; most viewers come away disappointed.
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The Crab Nebula is a remnant of a supernova, whose explosion occurred (or
rather, was visibly recorded) in July of 1054. Chinese and Japanese
astronomers witnessed the event. In fact, it would have been difficult
not to notice, for the night sky would have been lit up by a star with
the visual magnitude of about -5, bright enough to be seen even in the
daytime for nearly a month.
The star that exploded, producing the nebula, is now an optical pulsar.
Even now, nearly a thousand years later, the nebula is hurtling through
space at roughly a thousand kilometers per second. And it continues to
grow; the nebula is now over thirteen light years in diameter (four
parsecs) according to the Facts On File Dictionary of Astronomy.
M45, The Pleiades.
This open cluster contains as many as three thousand stars. The brightest
seven go under the name The Seven Sisters" (from brighter to dimmer):
Alcyone (eta Tauri), Electra, Maia, Merope, Taygeta, Celaeno, and Asterope.
Added to the list are also Pleione (BU Tauri = 28 Tauri), just east of
Alcyone, and Atlas (27 Tauri) who are actually Mum and Dad for the seven
sisters. (The two are often seen as one star; it takes a clear night to see
them as two separate stars.)
The Hyades
This open cluster of about two hundred stars is only 150 light years
away, and considered to be about 600 million years old. It is shaped
like a "V", just to the west of Aldebaran.
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Just as the Pleiades have individual names, so did the Hyades at one time.
In fact, these stars were supposed to be the half-sisters of the Pleiades,
and Robert Burnham (Celestial Handbook) gives their names - and a
great deal more on this group. Theta2 is the brightest star of
the group, which forms a binary with theta1 (see below). The group
is thought to be about 400 million years old.
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These nine stars, then, constitute the minimum count, easily seen with
the naked eye, while there are actually as many as 250 stars which belong
to the group. The cluster is estimated to be 415 light years away. Even a
small telescope brings this famous star cluster alive.
Hind's Variable Nebula
(NGC 1555)
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This curious deep sky object is located two degrees west of epsilon
Tauri, and two degrees north of delta Tauri. First look for the rather
dim variable T Tauri. Burnham (Celestial Handbook) has a finder's
chart, on page 1833. The star has an irregular variability, from 9 to
13.
Very close to T Tauri, just off to the west, is a cloud-like object. This
is Hind's Variable Nebula. Its variability is long-lasting; from 1869
to 1890 it couldn't be found at all. Presently, it seems to be gaining
slightly in visual magnitude, although its actual visual magnitude hasn't
been determined.
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