NGC 1543: de Vaucouleurs (1975) and Sandage & Brucato (1979). Outer-bar
measurements are from a DSS image; inner-bar measurements are from WFPC2
F814W images, with L_bar_ from the size of the stellar nuclear
ring. Outer disk inclination is from the axis ratio quoted in Buta &
Crocker (1993); distance is from Tonry et al. (2001, surface-brightness
fluctuation). See Fig. 3.
Dorado Group #28
Jan 28/29, 1979
103aO + GG385
NGC 1543 insert
Feb 7/8, 1978
103aO + GG385
NGC 1543 is an outlying member of the Dorado Group (Ferguson and
Sandage 1990). The group is part of a larger cloud complex and is
called G16 in the group catalog of de Vaucouleurs (1975).
NGC 1543 has what at first glance appears to be an external
ring. This feature is common to many of the galaxies on this and the
next four panels where the broken-external-ring form is
emphasized. The pattern, however, is not that of a detached complete
ring but again is composed of two tightly wound spiral arms that
nearly overlap after each unwinds by half a revolution.
The points of connection of the external, nearly circular
ring-like arms to the rim or the edge of the internal disk are often
very faint and hard to identify; yet the connection always does
exist. The pattern is similar to how the outer arms of NGC 0210 (panel
124) connect to its high-surface-brightness disk. We shall often call
this pattern the NGC 0210 look in the pages that follow.
The connection of the nearly circular outer spiral pattern to the
rim of the inner disk probably occurs in NGC 1543 at position angles
near 3:30 and 8:30 o'clock. Note the evidence for star formation in
the outer arms at the nearly symmetrical position angles of 2 and 7
o'clock. If NGC 1543 were seen less face on, it would have the NGC 210
look but at a much earlier position in the SBa classification sequence
than NGC 0210 itself (Sb). The external arms are exceedingly faint
On low-resolution plates such as those from Schmidt telescopes or
short-focal-length reflectors, the outer arms appear simply as an
extended, smooth halo with only a slight hint, if any, of the spiral
structure. The classification of RSB0 in the RC2, based on Mount
Stromlo 30-inch Reynolds reflector plates, is clearly
inappropriate. No S0 or SB0 galaxy in the standard system has a
morphology similar to that evident in the print here.
A very-high-contrast image of NGC 1543 is on panel 102. (Note the
rotation of the images here and there.)
The central bulge is surrounded by a zone of intermediate
luminosity. This is not seen in the insert here because of its very
high surface brightness, but it exists as an interior halo to the
bulge. This two-zone structure appears as one burned-out region in the
The bulge, as the first zone of the interior pattern, is itself
flattened, with its major axis perpendicular to the bar (the direction
is vertical in the orientation here).
The two ansae defining the bar stop on the rim of the
quite-low-surface-brightness disk. They are only just seen in the
insert here but are well visible in the high-contrast main print.
Jan 28/29, 1979
IIaO + GG385
The image of NGC 1543 on the print here shows the outer arms
better than does the low-contrast print on panel 100. (Note that the
prints here and there differ in their orientation.)
Two diametrically opposite, symmetrically placed regions of
recent star formation exist in the outer arms at position angles 4 and
10 o'clock on this print, In a way similar to NGC 1291 at the left,
NGC 5101 on the next panel, and NGC 2217 two panels ahead, these
regions of greatest star-formation rate in the arms occur at the same
place relative to the termination points of the bar on the rim of the
inner disk. Each occurs at mean position angles that are about 15 deg
advanced from the position angle of the termination of the bar, always
in the direction of the unwinding of the spiral outward.
This particular position of enhanced star formation occurs in the
arms of so many barred spirals of this type as to suggest that the bar
induces shocks at particular positions that are fixed relative to the
bar. This conclusion is discussed at greater length in the SBb
As in NGC 1291 at the left and in other barred spirals shown
earlier in this section, two symmetrically opposite regions of low
surface brightness exist in the disk, between the outer edge of the
inner disk and the inner edges of the outer arms. These regions of
reduced flux occur at position angles of about 2:30 and 8:30 o'clock
in the print here. As discussed previously, these positions are again
at nearly right angles to the position angle of the bar. The
phenomenon is expected (Athanassoula 1984).
Overexposed center and bar, pretty bright lens, very faint (R): 5.0 x -.
Overexposed center, pretty bright bar, few extremely faint knots on
faint (R): 4.9 x 4.2.
=ESO 118- G 10
extremely faint envelope
Massive diffuse bar that terminates
at the rim of a low-surface-brightness lens
whose diameter is approximately 2 arcmin.
Very high-surface-brightness inner bar within the nucleus,
tilted 70 degrees with respect to the main bar.
Large detached smooth outer ring 3.5 arcmin in diameter,
within which two opposite strings of resolved knots appear
as an embryonic spiral pattern with a small pitch angle.
These knots begin to resolve at B = 22 mag.
Atlas Gal. Austr., 1968.
Very bright nucleus.
Bar: 2.5 arcmin x 1.0 arcmin
(R): 4.7 arcmin x 4.7 arcmin.