Stars constellation Taurus is physically bound systems of stars in order of low compactness to high compactness (and in some sense also age).
They range from stellar associations, open clusters to globular clusters. Star clusters are held together by the gravitation of their members.
Due to both external (encounters with massive objects, influence of the host galaxy) and internal (encounters with other cluster members, stellar evolution) influences, this clusters slowly evaporate. Their lifetime varies from a few million years for loose associations to many billions (milliards) of years for massive globular.
Stars of constellation Taurus includes the bright star Aldebaran and two of the largest open star clusters visible from Earth... the Hyades and the Pleiades. It is located just Northwest of Orion the Hunter, with Aldebaran and the Hyades appearing together along a line between the Pleiades and Orion's three central stars which compose the "Belt" of the Hunter. Two other visible stars, Zeta Tau and Beta Tau denote the bull's horns, with Beta Tau (also known as El Nath) thought to be the "pushing" horn.
Aldebaran is the brightest star of constellation Taurus (also known as Alpha Tau). An orange-red giant which is the thirteenth brightest star in the heavens, it was one of the four Royal Stars of the Ancient Persians. Aldebaran appears to lie among the Hyades (with which it was once categorized) but is actually much closer to the Earth than that cluster, being about 68 light years away. In Arabic, Aldebaran means "the follower" (of the Pleiades) and it marks the "ruddy eye" of the bull.
Hyades are one of the major clusters in constellation Taurus. The stars which make up the Hyades are believed to be approximately 400 million years old. The brightest is Theta Tauris, an eclipsing binary...two stars which revolve around one another...each eclipsing the other's light when viewed from the Earth. The Hyades have been known since antiquity and the name itself dates back at least as far as 1000 B.C., when it was mentioned in various Greek sources. However, the Hyades was not recognized or classified as a cluster until the Twentieth Century.
The Pleiades, some 425 light years from Earth, form the shoulder of the bull and its hundreds of stars are thought to have formed around 100 million years ago.
On a reasonably dark night, it should be relatively easy to spot at least six of the stars which make up the Pleiades with the naked eye. If conditions are favorable, it may be possible to see as many as nine. Containing a total of more than 500 stars, the Pleiades is approximately 410 light years away and covers an area which is four times the size of the full Moon. Alcyone is the brightest star in the Pleiades cluster, being approximately 1000 times brighter than the Sun...and ten times larger.
Known astrologically as Supernova 1054, the Crab Nebula is one of only a few historically observed supernovae in the Milky Way Galaxy. It is the brightest supernova remnant in the sky, appearing as a tiny oval glow or cloud when viewed through binoculars or a small telescope, and one of the most studied objects in the heavens. The nebulous remnant was discovered by British amateur astronomer, John Bevis in 1731. Charles Messier, Astronomer to the French Navy, found the Crab Nebula independently on August 28, 1758, while searching the heavens for the return of Halley's Comet. However, it was not until the Mid-Nineteenth Century that it received its given name...when William Parsons, Third Earl of Rosse, noted that its extended filaments resembled the pincers of a crab.
In 1948, the Crab Nebula was identified as a strong source of radio radiation and established as a rapidly spinning neutron star rotating approximately 30 times every second. At the center of the Crab Nebula lies a pulsar, detected in 1968, which is all that remains of the exploded star's core. It continues to expand and will eventually disappear from the heavens altogether.
In essence, main stars constellation Taurus is the bright star Aldebaran and two major clusters Pleiades and Hyades which includes Crab Nebula.