NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-05-20 T00:58:31 PDT
Help | Comment | NED Home

Notes for object NGC 2985

16 note(s) found in NED.


1. 2007MNRAS.379.1249D
Re:NGC 2985
NGC 2985 is an early-type spiral galaxy, with regular gas and stellar
distributions. It is the control for NGC 4151. The disc orientation is
determined by an inclination of i = 40{degree} and a major-axis PA of PA =
180{degree}. Noordermeer et al. (2005) report a tidal interaction with its
companion NGC 3027.
The stellar velocity field of NGC 2985 shows a regular and symmetric pattern,
consistent with motions in an axisymmetric gravitational potential (Fig. 4e).
The PA of the kinematic major-axis (-2{degree}) is aligned with the photometric
major-axis of the outer disc. The velocity dispersion rises inwards, with 100 km
s^-1^ at 15 arcsec from the centre and 150 km s^-1^ in the inner 5 arcsec. There
is very little emission from the ionized gas H{beta} and [O III] in NGC 2985
(Fig. 4e). The emission-line flux peaks in the inner 2 arcsec with very little
flux outside. The H{beta} (Fig. B1) and [O III] (Fig. 4e) kinematics are
similar: the velocity fields are regular, showing the same overall symmetry as
the stellar velocity field. The gaseous velocity dispersion maps show no
specific features, with values rising towards the centre (200 km s^-1^ for [O
III] and 160 km s^-1^ for H{beta}). Finally, the [O iii]/H{beta} line ratio
reaches values up to 1.5-2 in the centre and decreases outwards (for r > 10
arcsec).

2. 2007MNRAS.376.1513N
Re:UGC 05253
The outer parts of the gas disc of UGC 5253 (NGC 2985) are dominated by a large
spiral arm extending from the north of the galaxy. Although the gas in the arm
is clearly rotating, it is impossible to determine the exact orientation of the
arm and we have only fitted a tilted ring model to the inner parts. Even so, our
rotation curve extends out to a radius of 49 kpc, or ~9R-band disc
scalelengths.
The most interesting aspect of UGC 5253, however, is the strong m = 0
component in the residual velocity field. Both in the inner (R <~ 200 arcsec)
and in the outer (R ~> 400 arcsec) regions, the residual velocities are small,
indicating that our fitted tilted ring model is an accurate description of the
observed gas motions. Around a radius of 300 arcsec (~=30 kpc), however, a
ring-like feature is detected in the residual field with an amplitude of -20 km
s^-1^. This feature has a high degree of symmetry with respect to the centre of
the galaxy and the residual velocities are almost constant with position angle;
only at the western end of the ring are the residuals slightly lower (~ -10 km
s^-1^). In the rotation curve, the feature manifests itself as a marked
asymmetry between the approaching and receding side. However, simple kinematical
asymmetries can only explain residuals along the major axis of a galaxy; without
additional radial motions, they must always vanish on the minor axis. The fact
that the residual velocities in the ring are so symmetric and also present on
the minor axis, argues against a simple explanation in terms of a kinematical
asymmetry.
A more plausible explanation of the marked m = 0 component in the residual
field is that it is induced by the gravitational perturbations from the large
spiral arm in the outer parts. It was shown by Schoenmakers, Franx & de Zeeuw
(1997) on theoretical grounds that an m = 1 perturbation in the gravitational
potential leads to a strong m = 0 term in the residual velocity field. The
combination of the large m = 1 spiral arm in the gas distribution of UGC 5253
and the pronounced m = 0 term in its residual field are thus a strong empirical
confirmation of their predictions. Furthermore, Schoenmakers et al. (1997)
showed that it is, in principle, possible to use the amplitude of the m = 0 term
in the residual field to measure the strength of the perturbation on the
potential. This analysis is, however, beyond the scope of this paper and will be
postponed to a later time.
Alternatively, we could be seeing a vertical vibrational mode in the gas disc
of UGC 5253, where the entire ring is moving upwards (i.e. towards us) with
respect to the rest of the galaxy. Sellwood (1996) and Edelsohn & Elmegreen
(1997) showed the results of N-body simulations which suggest that vertical
vibrations can exist in the discs of galaxies, possibly triggered by a tidal
interaction with a companion galaxy. It seems, however, questionable if such a
mechanism could explain the highly symmetric feature we observe in UGC 5253, and
we judge the explanation of Schoenmakers et al. (1997) more plausible.
Note that the feature in the residual field coincides with a marked drop in
the rotation curve. Both inside R = 200 arcsec and outside R = 400 arcsec, the
rotation curve is flat, but around R = 300 arcsec, it suddenly drops from 245 to
210 km s^-1^; the rate of the decline is consistent with pure Keplerian decay.
Whether it is a coincidence that this drop occurs at similar radii as the
feature in the residual field, or whether both effects are related, is unclear.

3. 2005A&A...442..137N
Re:UGC 05253
The main disk of UGC 5253 (NGC 2985) is regular in its distribution and
kinematics. In the outer parts, a large one-armed spiral of gas is seen to
extend towards a small "blob" of gas southwest of the galaxy. UGC 5253 lies
about 20' west of the late-type spiral UGC 5316, which also has a disturbed
morphology (e.g. Vorontsov-Vel'Yaminov 1977). The redshifts of the two systems
differ by about 250 km s^-1^ only, so the peculiar structures of both galaxies
could well be the result of a tidal interaction.

4. 2003ApJS..146..353M
Re:NGC 2985
NGC 2985 (TW)
This is one of the prototypes of the tightly wound nuclear spiral
class and is also shown in Figure 3. While the nuclear spiral does
appear to branch into additional dust lanes at larger radii, the main
spiral arm remains coherent.

5. 2002A&A...389...68G
Re:NGC 2985
NGC 2985: the HII region distribution is quite irregular, but
despite this fact, the first method gives values in reasonable
agreement with the RC3 (1991) catalog. The second method does
not work. We adopt the mean between our first method and
RC3 (1991).

6. 2002A&A...387..821G
Re:UGC 05253
UGC 5253 (NGC 2985)
The H{alpha} emission in this early type galaxy is almost
uniformly distributed in a ringlike structure, between 6 arcsec
and 40 arcsec from the nucleus, with no emission at all in the
center and faint emission in the spiral arms around the ring.
The isovelocity lines are fairly symmetric, with classical
distortions when crossing the spiral arms. The velocity gradient
in the center is very high and the rotation curve rapidly reaches
a plateau at 240 km s^-1^. The WHISP data indicate a faint HI
column density in the main body and a large off-centered ring,
about 16 arcsec in diameter.

7. 2001A&A...368...16M
Re:NGC 2985
14. NGC 2985 is an Sab spiral with very regular, tight arms. The fit
procedure worked very good, the corresponding low residuum is shown in
Fig. 4 (in on-line version).

8. 2000ApJS..129...93F
Re:NGC 2985
NGC 2985. - We detect a 1.9 mJy source. At 2.5" resolution, the
source is slightly extended in the north-south direction, along the
orientation of the optical galaxy. The tapered map shows a 2.7 mJy core
and about 1 mJy weak low surface brightness emission to the southwest.
The object was also detected in the NVSS: 44.1 mJy. At 1.49 GHz, 1.0'
resolution, Condon (1987) measured a total flux of 61.9 mJy: the radio
emission of NGC 2985 must be extended over tens of arcseconds.

9. 1997ApJS..112..391H
Re:NGC 2985
NGC 2985.--A moderately weak (f_blend_~22%) broad H{alpha} component may be
necessary to account for the shelf of excess emission discernible in the gaps
between H{alpha} and [N II] (Fig. 9d). However, because of the low quality of
the data in the [S II] region, we cannot rule out the possibility that the
excess emission originates from weak, intrinsically broad wings in the
narrow-line profile. Thus, at this point, we will regard the broad H{alpha}
detection only as tentative. That the narrow component of H{alpha} is slightly
narrower than [N II] (resulting in relatively pronounced residuals) can
probably be attributed to imperfect removal of H{alpha} absorption.

10. 1997ApJS..108..155G
Re:NGC 2985
This LINER in a early-type galaxy shows a compact nucleus surrounded by a
disk with 110 H II regions detected. The pattern of star formation is
bimodal, with most of the regions located between 1 and 5 kpc, and a few
scattered outside this radius.

11. 1994CAG1..B...0000S
Re:NGC 2985
Sab(s)
PH-7712-S
Feb 11/12, 1980
103aO
12 min
Racine wedge
NGC 2985 is of the MAS type. Fragments of arms can be traced
throughout the underlying disk over its entire face, continuing very
close into the center. The regularity and tightness of the spiral
pattern and the thinness of the arm fragments are the criteria for the
Sab classification rather than Sb.
The plate was made with a Racine wedge in the optical path. This
gives double images with a magnitude difference of 5 mag and an
angular separation of 18".

12. 1993A&AS...97..887B
Re:NGC 2985
NGC 2985 is an early type LINER (SM) with fairly weak CO emission. Our
central CO(2-1) spectrum at 12" resolution has exactly the same velocity
and width as the PR CO(1-0) spectrum at 1' resolution. Assuming an
inclination of 38^deg^, the molecular gas is rotating at 250-300 km/s at
400-900 pc from the center. The lack of emission at the central velocity
is also interesting and this combination makes NGC 2985 a good nuclear
ring candidate for observation at other wavelengths.

13. 1976RC2...C...0000d
Re:NGC 2985
Non-interacting pair with NGC 3027 at 25 arcmin

14. 1973UGC...C...0000N
Re:UGC 05253
{(R')}SA(rs)ab (de Vaucouleurs), Sb+ (Holmberg)
Paired with UGC 05316 at 24.8, 102
Extremely faint outskirts to approximately 7. x 6.
{UGC incorrectly notes "Pec". H. Corwin}

15. 1964RC1...C...0000d
Re:NGC 2985
Small, diffuse, very bright nucleus. Many poorly resolved knotty arms.
Weak outer whorls form pseudo (R): 2.6 arcmin x 1.9 arcmin.
Non-interacting pair with NGC 3027 at 25 arcmin.
Heidelberg Veroff. Vol. 9, 1926 dimensions (1.6 arcmin x 1.4 arcmin) are
for bright part only.

16. 1918PLicO..13....9C
Re:NGC 2985
Slightly elongated; 3' long. There is a bright stellar nucleus; the whorls are
quite condensed and rather patchy near the center, fainter and much more
open farther out. 12 s.n.


Back to NED Home