The Caldwell Objects

41
Owners of spectroscopes may
want to test the instruments on
Taurus's most prominent star.
As Ernst Hartung notes in his
Astronomical Objects for Southern
Telescopes, Aldebaran displays a
"fine absorption spectrum
crossed by many dark bands
and lines," some of which are
visible with a 3-inch telescope.
Eighteenth-century spectroscopic
studies of Aldebaran
revealed the presence of hydrogen,
sodium, magnesium,
calcium, iron, bismuth, tellurium,
and mercury in the star's
atmosphere. Of these findings
Garrett P Serviss . wrote
somewhat prophetically in his
1888 Astronomy with an Opera-
Glass: "And so mod
ern discoveries, while they have pushed back the
stars to distances of which the ancients could not
conceive, have, at the same time, and equally,
widened the recognized boundaries of the
physical universe and abolished forever the
ancient distinction between the heavens and the
earth. It is a plain road from the earth to the stars,
though mortal feet can not tread it."
W skywatchers e don't need feet to traverse
the corridors of space; all we need are knowledge
and imagination. So pick up a pair of binoculars
and use your mind to probe the wonders of the
Hyades. Even the smallest of binoculars and a
little resourcefulness can transform the celestial V
into a three-dimensional cityscape of bright
lights. T mentally o cross the cluster's heart you
will need to travel about 10 light-years (95 trillion
km); the outlying Hyads are spread over a region
at least
166
twice as wide. Now drop the binoculars and look
at the Hyades with your naked eyes. Also known
as the Taurus Moving Cluster, the Hyades are
drifting through space at 46 km per second
toward a point a few degrees east of Betelgeuse.
According to European Space Agency scientist
Jos de Bruijne, the cluster was closest to our solar
system some 1,150,000 years ago, and in 50
million years it will be but a dim, ½°-wide
telescopic target.
Now compare the Hyades' appearance with
that of the Pleiades, using both the naked eye and
binoculars. Although the Pleiades cluster is a
mere 10° from the Hyades, it is 256 light-years
more distant. And if, with their profusion of
yellowish stars, the Hyades look older than the
Pleiades to you, give yourself a pat on the back!
The age of the Hyades is 625 million years old,
about 10 times that of the Pleiades. (I wonder
what Atlas would have to say about
Deep-Sky Companions: The Caldwell Objects