NGC 4643 -- Barred Lenticular Galaxy in Virgo
A Galaxy with a Ring
The Barred Lenticular Galaxy NGC 4643 does not jump out at the eyepiece in my 155mm
refractor under suburban skies. This nearly face-on, small-sized galaxy appears as a tiny fuzzy
star at low and medium powers. Only with an increase in magnification could I begin to make
out the nucleus and bar within its circular glow (you may have to enlarge the drawing to see my
sketch of the bar).
This galaxy is far more interesting when seen with the mind’s eye. It is a huge collection of stars
and dust (even for a galaxy) that extends 107,000 light years across. The tiny central bar in the
drawing is 40,000 light years long. Far more interesting (and way below the reach of my
telescope) is that this galaxy has an external Polar-Ring that extends 228,000 light years from
end to end. Galaxies generally do not have such structures and as far as I am aware, when
they rarely do, it is not a ring that runs perpendicular to the galaxy’s disk. This galactic ring
debris is probably due to an ancient merger of two galaxies into one.
Like so much of my astronomy, knowing a little about the object I am looking at adds layers of
interest to the observing session. It is the mind that sees a tiny insignificant looking smudge in
the eyepiece as a unique collection of billions upon billions of stars.