Triplet [with NGC 3440 and NGC 3458]
Feb 4/5, 1981
NGC 3445 forms a triplet with NGC 3440
(possible Sbc merger in progress; not in the RSA)
at a separation of 9.9', and NGC 3458 (SB0,
panel 54) at a separation of 14.0'. The redshifts
are v_o(3440) = 2021 km/s, v_o(3445) = 2083 km/s,
and v_o(3458) = 1899 km/s. At the mean
redshift distance of 40 Mpc (H = 50) the
projected linear separations of NGC 3440 and
NGC 3458 from NGC 3445 are 115 kpc and
163 kpc, respectively.
The importance of the triplet is that the
morphological types for two of the companions
are so very different (Sc and SB0). The case is
similar to that of NGC 5480/5481 on the preceding
The face of NGC 3445 is covered with a
thick spiral pattern within which numerous
HII-region candidates exist. At the end of the single
principal arm is a shred that may be a separate
galaxy (or was at one time). The angular separation
of the shred from the center of NGC 3445 is
1.2', which is a projected linear separation of
only 14 kpc. This close pair is number 256 in
Karachentsev's catalog of pairs. He lists the
redshifts of v_o(3445) = 2058 km/s and v_o = 2004 km/s
for the shred which he classifies as type Sm.
= Arp 24
= Kara 256a
In a group with NGC 3440 and NGC 3458.
VV 14, Arp 24
In Arp's class "one-armed (unilateral) spiral galaxies"
SAB(s)m (de Vaucouleurs)
Interacting with companion at 1.3, 105, 0.4 x 0.15, bridge
Small, bright nucleus in a complex bar-like core. One knotty, massive arm
ending in an elongated patch: 0.4 arcmin x 0.1 arcmin.
See H.A., 105, 230, 1937.
In the NGC 3440-3445-3458 Group.