Date and Time of the Query: 2019-04-22 T19:04:23 PDT
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Notes for object NGC 3646

6 note(s) found in NED.

1. 2002ApJS..143...73E
Re:NGC 3646
NGC 3646.---SABab pec: Nuclear point source embedded in a small, very
flattened bulge. An asymmetric inner disk surrounds the bulge. The
inner disk is more extended to the NW than to the SE. The NW side of
the inner disk has a number of knots. The spiral pattern is very odd.
One spiral arm emerges from the SE end of the inner disk and turns
counterclockwise. Another emerges from the NW side of the inner disk
and turns clockwise. These two arms appear to merge on the SW side of
the galaxy, joining in a point. The arm structure on the west side is
very well defined, and HSB, with many bright knots. On the east side,
the arms are diffuse and patchy, with fewer knots. There is an LSB
outer disk on the west side. The referee suggests, and we agree, that
this may be an example of a galaxy with visible leading and trailing

2. 1994CAG1..B...0000S
Re:NGC 3646
Sbc(r)II pec
Karachentsev 281
Jan 6/7, 1946
60 min
The morphology of NGC 3646 is peculiar,
as if the result of an encounter. The outer spiral
pattern cannot be traced even as to the sense of
direction, but the inner spiral pattern is regular.
NGC 3646 forms a physical pair with NGC 3649
(SBa; not in the RSA) at an angular separation
of 8'. The redshifts from the catalog of
Karachentsev (1987) are v_o(3646) = 4227 km/s
and v_o(3649) = 4322 km/s. At the mean
redshift distance of 85 Mpc (H = 50), the
projected linear separation is 200 kpc. However,
there is no indication of morphological distortion
in the spiral pattern of NGC 3649. The peculiar
outer ring structure in NGC 3646 here cannot be
attributed to interaction with NGC 3649.
NGC 3649 is much smaller in angular
diameter than NGC 3646. The diameters are 80"
for NGC 3649 and 260" for the outer ring of
NGC 3646. Note that the inner part of NGC 3646
resembles a normal Sbc spiral of the same
size as NGC 3649. The linear diameter of this
inner part is 33 kpc - a normal value for most
RSA spirals. However, the outer ring of NGC 3646
has a linear diameter of 107 kpc, which is
abnormally large.
The fact that the inner image of NGC 3646
has a normal morphology and is of normal size
suggests that the ring is a result of a dynamical
process such as the dropping of one galaxy
through another, as postulated by Theys and
Spiegel (1976, 1977) and by Lynds and Toomre
(1976) in other ring galaxies. The abnormal
velocity field and an early comment on the large
linear diameter of the ring are given by Burbidge,
Burbidge, and Prendergast (1961).

3. 1976RC2...C...0000d
Re:NGC 3646
= Kara[72] 281
Pair at 7.8 arcmin

4. 1973UGC...C...0000N
Re:UGC 06376
{(R')}SA(r)bc pec? (de Vaucouleurs), Sc- (Holmberg)
Amorphous disk with patchy broken arms, nucleus eccentric in (R) 2.5 x 1.3
UGC 06386 at 7.8, 72
{UGC incorrectly notes "Pec". H. Corwin}

5. 1964RC1...C...0000d
Re:NGC 3646
Small, bright nucleus. (r): 0.7 arcmin x 0.3 arcmin. Very strong, knotty (R):
2.1 arcmin x 1.0 arcmin. Knotty branching arms outside (R). (r) and nucleus
not in center of (R).
Non-interacting pair with NGC 3649 at 7.8 arcmin.
Lick (1956) and Burbidge (1961) velocity in agreement for emission patch
70 arcsec south-west: +4080 km/sec.
Photograph, Rotation and Mass:
Ap. J., 134, 236, 1961.
Ap. J., 138, 887, 1963.
Ap. J., 135, 699, 1962.

6. 1956AJ.....61...97H
Re:NGC 3646
HMS Note No. 111
Only H and K in nucleus.
HMS Note No. 112
Emission H{beta} and {lambda} 3727 in emission patch 70 arcsec
[south-west] of the nucleus.
Patch fell on extreme end of slit, so difference in redshift
is not very reliable.
Nevertheless, the [south-west] end probably is approaching
with respect to the center.

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