3.3 NGC 5122 (B-16)
NGC 5122 is a relatively nearby and well-known polar-ring galaxy. The H I
velocity field indicates that the gas in the ring rotates around the major
axis of the central galaxy, while stellar absorption-line spectra show
rotation of the central galaxy around its minor axis (Cox 1996). The mass
of H I associated with NGC 5122 is ~2 x 10^9^ M_sun_ (Cox 1996; Huchtmeier
1997). The galaxy has a nearby gas-rich companion (MCG -02-34-45)
(Cox 1996). Our emission-line heliocentric velocity (2818 +/- 10 km s^-1^)
is in agreement with H I measurements: 2855 km s^-1^ (Cox 1996),
2842 +/- 10 km s^-1^ (Huchtmeier 1997).
The emission-line properties are typical for LINER nuclei (e.g.
Veilleux & Osterbrock 1987).
B-16 = NGC 5122. (N,V) Listed as one of the disc-dominated PRGs with
large polar rings by Reshetnikov & Sotnikova (1997). Its faint ring is
smooth and warped, and very nearly perpendicular to the disc, and both
are seen nearly edge-on; CCD image by J. Gallagher & L. Matthews: in Cox
et al. (1995). Stellar absorption lines only were found by Rodgers et
al. (1978). The galaxy was observed at a higher, incorrect redshift, at
both Green Bank and Nancay. The galaxy was detected in Nancay at the
correct redshift by Theureau et al. (1998), see Table 3; no confusing
objects were found within the Nancay search area. Mapped in H I at the
VLA (Cox et al. 1995), who found that the H I is associated with the
ring, not with the host galaxy. The ring is asymmetric and extends
towards a companion galaxy, MCG-02-34-045, a 15.5 mag Sc/d object at
V_hel_ = 2929 km s^-1^ (74 km s^-1^ higher than that of the PRG) at 11.6'
distance. The polar ring gas is not warped, and no gaseous bridge is
visible between the two companion galaxies.
B-16 = NGC 5122. An unreliable optical redshift caused us to miss this
galaxy in our GB 140' run. The spectrum at the coordinates of NGC 5122,
but at a higher, incorrect redshift, is shown in Fig.1; it appears that
there is significant flux at 4800 km s^-1^. Subsequent observations at
the VLA (Cox et al, 1994, in preparation) has revealed that about
5 x 10^8^ M_sun_ of gas is associated with the ring of NGC 5122 itself,
and an equal amount is in a companion (MCG -02-34-045) 10' and about 100
km s^-1^ away. NED lists no other companions within 20'. The VLA map,
along with optical long-slit spectroscopy of the central body (Jarvis and
Sackett, unpublished), confirms this galaxy as a polar ring.
This lenticular galaxy has a relatively blue continuum and high