Bar is visible in both the ellipse fits and the K_S_image. The rise in
ellipticity beyond ~20" is due to the spiral arms.
March 22/23, 1982
103aO + GG385
The bar in NGC 5156 is well formed and
ends on the rim of one of the best-defined
almost-complete rings in the RSA. The arms do not
start exactly from the ends of the bar as in NGC 1300,
but instead begin from about 50^deg^ downstream
from each bar tip. This large downstream position
(see previous descriptions of this
phenomenon in this section) cause different arm
segments to nearly overlap, creating the impression
of a complete inner ring. The pattern is
reproduced in some of the models of Huntley
(1980) by changing the fraction of the total mass
that is in gas.
Very bright nucleus, bar(:), very bright (r): 0.5 x 0.4. Faint arms
with knots. Many stars superposed.
Two thin well-developed arms of high-surface-brightness that
are lumpy with HII regions,
but with no chance of resolution at the 0.5-1.0 arcsec level.
Small, bright nucleus.
There is a small nebulous knot 1.2 arcmin north-preceding.
There is a faint star 0.4 arcmin following.