NGC 4984: Jungwiert et al. (1997). Bar measurements are from the ellipse
fits and isophotes in Jungwiert et al., with L_bar_ for the outer bar
from the inner-ring size listed in Buta & Crocker (1993). Because the
galaxy has prominent inner and outer rings (the RC3 position angle is
basically that of the inner ring/lens), the outer disk orientation is
based on considerations of typical inner- and outer-ring orientations
and axis ratios compared with those of the galaxy's rings, similar to
the approach used in Erwin & Sparke (2003,1999) for other galaxies with
strong outer rings.
NGC 4984 (RSAB0+, 1"~73 pc, I=45.9^deg^)
The ellipticity peak (e_max_=0.23) around a=4" is associated with a short
plateau in the PA (64^deg^ between 2.9 and 4.1"). Since the peak is even better
seen after deprojection (PA_disk_=15^deg^), we believe that it indicates the
presence of a short bar. The outer ellipticity maximum (e_max_=0.30 at a=30")
is related to the primary bar. Both bars are intrinsically nearly parallel
provided the deprojection is correct (cf. Fig. 3).
Feb 22/23, 1979
103aO + GG385
The spiral pattern in the inner disk of NGC
4984 is made up of multiple dust arms, shown in
the insert. A second set of faint luminous spiral
arms, which are smooth and relatively thin, exists
outside the main body and can be seen on the
main print by viewing from a distance. The
pattern is that of a two-armed spiral attached to the
main body at about 12:30 and 6:30 o'clock on
the print here.
There is yet a fainter spiral arm farther out
on the left side of the main print, halfway again
as far from the center as the first faint outer
spiral. This second outer arm, visible on the
plate, is faintly visible on the original print, but
may not be visible on the halftone reproduction
here. This outer structure has been called a ring
in the RC2 classification, as RS0/RSB0, but this
interpretation is not supported by the material
here. Both the inner dust lanes and the two outer
rings have a spiral pattern. The galaxy is a very
NGC 4984. It is lenticular in appearance and is classified by
de Vaucouleurs, de Vaucouleurs, and Corwin (1976) as S0 (T= -1). The
heliocentric velocity measured by us agrees well with the value
v_H_=+1259 km s^-1^ given by Sandage (1971). The spectroscopic
continuum is relatively blue.
vdB - Snn
Morg - gkD2 and kD2
deV - (R)SAB(rs)0+.
Photo: Lund Ann. No 10.
Extremely bright nucleus. Bright smooth lens: 1.3 arcmin x 1.1 arcmin with
spiral pattern of dark lanes. Faint (R): 2.8 arcmin x 1.8 arcmin.
Lund 7 and Helwan 30 dimensions (4 arcmin x 0.5 arcmin) were rejected, wrong