VirgoVirgo
VI. sign of zodiac
Particulars:
General:
Virgo is the 6th sign of the zodiac; the sun passes through this constellation from late september to the end of october. It is the second largest constellation in the sky (the largest is Hydra). The most outstanding Virgo Supercluster of galaxies is located on the northern border of Virgo reaching into the neighbouring constellation of Coma Berenices. The brightest galaxies can be located with small telescopes as faintly glowing patches of light. This supercluster is about 65 million lightyears away. (Because its lying half in Coma Berenices it is often referred as Virgo-Coma Supercluster.)
Stars and other objects
In a distance of 260 lightyears lies the leading star, alpha
Vir, Spica (meaning the ear of wheat), a
blue-white star of 1.0 mag. The fact that in its neighborhood
nearly no other bright stars are found gives it an additional
brilliance in the sky.
Gamma Vir consists of two yellow-white, nearly equal stars
in brightness: one with 3.6 mag, the other with 3.7 mag. With a
small telescope (about 50mm aperture) the two components can be
resolved. The stars revolve around one another with a period of
177.75 years. As seen from Earth they are currently closing
together. By the year 2000 AD it will require telescopes with an
aperture of 100mm to split them. They will reach their closest
point together (also mark: as seen from Earth!) in 2007 AD. At
this time it will be impossible for amateur telescopes to resolve
the components.
In small telescopes the pair of 4th mag and 9th mag stars of theta
Vir can be viewed.
Also with small telescopes tau Vir can be split in its 4th
mag star with the unrelated 9th mag star.
S Vir is a long-period variable of a terrific red color.
Its brightness varies with a period of 377 days during which it
falls down from 6th mag to 13th mag. This star is an interesting
telescopic object.
Early 1997 a supernova of mag 13.5 has been reported (IAU circular 6552).
SN1997X flashed up in NGC4691 (RA = 12h 48m 14.28s, DECL = -3
19'58".5).
As noted above there are lots of galaxies in this constellation;
most of them belonging to the Virgo-Supercluster. One exception
is the famous Sombrero Galaxy, M 104. It
lies on the border to Corvus. Its highly irregular shape reminds
in some ways on a sombrero.
All other galaxies are assiciated with the Supercluster. Most
famous is the giant galaxy M 87 in the center of the
cluster. Scientists believe that a black hole dwells in the
center of M 87. This galaxy is also known for its strong
radio source Virgo A.
A nice pair for observing are the 9th mag elliptical galaxies M
84 and M 86.
For detailed information about M 49, M 58, M 59, M 60, M 61, M
89 and M 90 (as well as of the other galaxies) please
refer to the Messier database.
Three meteor showers seem to origin from Virgo: the Eta
Virginids, Theta Virginids and the Pi Virginids. Observations
showed a durartion for the Eta Virginids from February,
24th, to March, 27th. There seems to be no specific maximum for
this weak shower. The Theta Virginids last from March,
10th, to April, 21st. Although this isn't a strong shower,
either, a maximum occurs around March, 20th. The strongest shower
of these three with an hourly rate from 3-5 meteors are the Pi
Virginids. The duration of this shower extends from
Februrary, 13th, to April, 8th. Detailes information about these
meteor showers can be found in the database of Gary Kronk.
Mythological Background:
In various legends Virgo represents the goddess of justice or the goddess of the harvest.