A&A 386, 140-148 (2002)
DOI: 10.1051/0004-6361:20020227
W. van Driel1 - F. Combes2 - M. Arnaboldi3 - L. S. Sparke4
1 - GEPI, Observatoire de Paris, Section de Meudon,
5 place Jules Janssen, 92195 Meudon, France
2 -
LERMA, Observatoire de Paris, 61 avenue de l'Observatoire,
75014 Paris, France
3 -
Osservatorio Astronomico di Capodimonte, V. Moiariello 16,
Napoli 80131, Italy
4 -
Astronomy Department, University of Wisconsin-Madison,
475 N. Charter St., Madison WI 53706, USA
Received 13 December 2001 / Accepted 5 February 2002
Abstract
A total of 33 polar ring galaxies and polar ring galaxy candidates were observed in
the 21-cm H I line with the 64-m Parkes radio telescope. The objects, selected by
their optical morphology, are all south of declination -39
and in only 5 of them H I had been reported previously.
H I line emission was detected towards 18 objects, though
in 3 cases the detection may be confused by another galaxy in the
telescope beam, and one is a marginal detection.
Eight objects were detected for the first time in H I, of which 5 did not have
previously known redshifts.
Key words: galaxies: distances and redshifts - galaxies: general - galaxies: ISM - radio lines: galaxies
The catalogue of Whitmore et al. (1990, hereafter PRC) provides us with over a hundred known polar-ring galaxies and PRG candidates, as well as a list of possibly related systems, divided into the four main categories listed below. The updated number of objects per category listed here is different from that tabulated originally in the PRC, as since its publication the following 4 category B and 4 category C objects have been promoted to category A: B-03 (=IC 1689), B-17 (=UGC 9562), B-19 (=AM 2020-504), B-21 (=ESO603-G21), C-13 (=NGC 660), C-24 (=UGC 4261), C-27 (=UGC 4385) and C-45 (=NGC 5128); see references in Paper III. All of these will be considered members of the A category in our studies - note that of these objects only B-19 was observed in our present Parkes survey.
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Figure 1:
Optical Digital Sky Survey images of all 18 PRC objects towards which
H I line emission was detected at Parkes. Each galaxy is identified by its PRC name.
Each image has a size of
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Open with DEXTER |
In Sect. 2 of the present paper the sample of PRGs observed in H I at Parkes is presented. The observations are described in Sect. 3, a brief discussion of the results is given in Sect. 4 and the conclusions are summarized in Sect. 5. An analysis of these, and all other available H I data on PRGs and related objects will be presented in Paper V in these series (van Driel et al. in preparation).
Of the 33 PRC objects observed at Parkes, 28 were selected using the following criteria:
(1) South of declination -39
(the limit of our Nançay survey;
our Green Bank survey reached -45
),
(2) from PRC Categories A, B or C , and
(3) no published H I detection and not detected in the Parkes HIPASS
Public Data Release spectra
http://www.atnf.csiro.au/research/multibeam/release/.
Of these 28, 14 have optical redshifts, 5 of which (of B-25, B-26, B-27, C-65 and C-72)
are outside the range of the HIPASS spectra, -1281 to 12 741 km s-1.
Besides the 28 objects thus selected, the telescope time allocation also permitted us to observe the following 6 objects: three (PRC A-05 = NGC 4650A, C-11 = NGC 625 and C-42 = NGC 4672) that were detected in HIPASS and previously reported as detected in the literature, two (C-15 = ESO 199-IG12 and C-55 = ESO 143-G37) that were detected in HIPAS, and one (C-14 = NGC 979) whose previously reported detection seems due to radio interference. For details on the available H I data for all objects we refer to Table 2 and Sect. 4.1.
Table 1. Basic data for the Parkes polar ring galaxy
H I survey sample.
PRC | Ident. | RA | Dec |
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D25 |
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W50 | W20 |
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rms | D | LB |
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[log] | [log] | ||||||||||||||
(J2000.0) | km s-1 | mag | ' | km s-1 | km s-1 | km s-1 | Jy km s-1 | mJy | Mpc |
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Kinematically-determined polar-ring galaxies | |||||||||||||||
A-05 | NGC 4650A | 12 44 48.8 | -40 42 50 | 2808 ![]() |
13.91 | 1.5 | 2880 ![]() |
221 | 240 | 19.5 | 7.3 | 35.9 | 9.74 | 9.77 | 1.1 |
B-19 | AM 2020-504 | 20 23 54.8 | -50 39 05 | 4989 ![]() |
15.97 | 1.2 | 5006 ![]() |
390 | 650: | 6.1 | 4.4 | 65.5 | 9.44 | 9.44 | 2.2 |
Good candidates for polar-ring galaxies | |||||||||||||||
B-02 | PGC 419347 | 01 15 28.7 | -54 26 53 | 16.83 | 0.4 | 5361 ![]() |
98 | 225: | 1.7 | 3.3 | 70.0 | 9.15 | confused? | ||
B-04 | PGC 145741 | 03 37 57.6 | -48 55 40 | (16.61) | 0.6 | <3.6 | 4.5/3.6 | <2.4 | |||||||
B-05 | PGC 415379 | 03 52 49.2 | -54 49 50 | 16.46 | 0.5 | <4.1 | 4.4/4.7 | <2.4 | |||||||
B-06 | AM 0442-622 | 04 43 07.6 | -62 19 42 | 16.32 | 0.6 | 7165 ![]() |
308 | 435 | 2.8 | 3.8 | 92.7 | 9.60 | 9.76 | 1.4 | |
B-18 | AM 1934-563 | 19 38 38.7 | -56 27 30 | 11 649 ![]() |
15.93 | 0.6 | 11 282 ![]() |
193 | 308 | 4.1 | 3.3 | 153.8 | 10.19 | confused | |
B-22 | PGC 13177 | 23 31 54.6 | -40 45 45 | 15.11 | 0.8 | <3.9 | 4.5/4.2 | <0.65 | |||||||
B-25 | PGC 164989 | 23 51 41.3 | -39 10 31 | (19 540 ![]() |
16.08 | 0.6 | <6.6 | 4.4 | 260.4 | 10.59 | <11.0 | <2.7 | |||
B-26 | PGC 165022 | 23 53 20.1 | -40 25 53 | (16 470) | (16.74) | 0.7 | <4.6 | 4.4 | 219.3 | 10.18 | <10.7 | <3.5 | |||
B-27 | ESO 293-IG17 | 23 56 25.3 | -39 10 36 | 15 300 ![]() |
16.17 | 1.0 | <5.4 | 4.5 | 203.8 | 10.34 | <10.7 | <2.4 | |||
Possible candidates for polar-ring galaxies | |||||||||||||||
C-07 | ESO 113-IG4 | 01 00 34.2 | -57 44 56 | 3130 ![]() |
15.67 | 0.6 | 3587 ![]() |
131 | 275: | 2.1 | 4.3 | 46.2 | 9.25 | 9.03 | 0.6 |
C-08 | ESO 243-IG19 | 01 02 49.2 | -47 11 12 | 16.05 | 0.6 | 6438 ![]() |
335 | 435 | 3.2 | 5.1 | 84.9 | 9.63 | 9.73 | 1.3 | |
C-10 | ESO 152-IG3 | 01 28 24.8 | -52 38 08 | 3450 ![]() |
16.17 | 0.4 | <2.5 | 5.9 | 44.6 | 9.02 | <9.1 | <1.1 | |||
C-11 | NGC 625 | 01 35 04.2 | -41 26 15 | 391 ![]() |
11.61 | 6.3 | 396 ![]() |
79 | 112 | 32.1 | 9.9 | 4.6 | 8.87 | 8.20 | 0.2 |
C-14 | NGC 979 | 02 31 38.7 | -44 31 28 | 14.22 | 1.1 | [5181 | 241 | 2.1 | 3.3] | <0.22 | |||||
C-15 | ESO 199-IG12 | 03 03 24.2 | -50 29 51 | 7030 ![]() |
14.80 | 1.4 | 6873 ![]() |
409 | 532 | 10.0 | 5.6 | 89.8 | 10.18 | 10.28 | 1.3 |
C-16 | AM 0320-495 | 03 21 56.0 | -49 48 03 | 16.11 | 0.7 | <4.0 | 3.8/5.1 | <1.7 | |||||||
C-20 | ESO 201-IG26 | 04 15 17.6 | -50 56 43 | 3802 ![]() |
15.45 | 0.6 | 3745 ![]() |
213 | 225 | 4.1 | 5.2 | 47.7 | 9.37 | 9.35 | 0.95 |
C-21 | PGC 495219 | 04 16 18.9 | -47 49 14 | 16.88 | 0.6 | <3.7 | 4.0/4.2 | <3.2 | |||||||
C-22 | ESO 202-G1 | 04 16 31.1 | -47 50 51 | 10 052 ![]() |
14.73 | 1.3 | 9780 ![]() |
220 | 315: | 1.4 | 3.1 | 128.2 | 10.52 | marginal | |
C-42 | NGC 4672 | 12 46 15.4 | -41 42 22 | 3346 ![]() |
14.10 | 2.2 | 3202 ![]() |
343 | 377 | 12.7 | 4.8 | 46.5 | 9.89 | 9.81 | 0.84 |
C-48 | ESO 326-IG6 | 14 11 08.5 | -40 06 22 | 8598 ![]() |
15.32 | 0.9 | <5.3 | 5.1 | 111.3 | 10.16 | <10.2 | <1.1 | |||
C-52 | ESO 232-G4 | 19 22 46.6 | -51 00 08 | 5600: ![]() |
14.81 | 1.3 | 4951 ![]() |
320 | 385 | 2.5 | 3.6 | 64.5 | 9.89 | 9.54 | 0.45 |
C-53 | IC 4982 | 20 20 37.1 | -71 01 45 | 15.58 | 0.6 | 6180 ![]() |
190 | 235 | 2.9 | 4.6 | 80.0 | 9.77 | 9.63 | 0.74 | |
C-55 | ESO 143-G37 | 20 37 48.0 | -61 44 50 | 16.42 | 0.7 | 3265 ![]() |
90 | 151 | 4.8 | 5.1 | 42.2 | 8.87 | 9.31 | 2.7 | |
C-56 | PGC 128148 | 20 44 11.6 | -61 59 19 | 15.75 | 0.8 | 3335 ![]() |
259 | 485 | 5.7 | 4.4 | 42.6 | 9.15 | 9.38 | 1.7 | |
C-61 | PGC 263886 | 21 20 56.6 | -72 20 17 | 16.11 | 0.5 | <4.4 | 4.3/5.5 | <1.8 | |||||||
C-62 | ESO 236-IG2 | 21 19 46.8 | -52 14 16 | 16.35 | 0.5 | <4.1 | 4.2/4.8 | <2.1 | |||||||
C-65 | ESO 287-IG50 | 21 41 57.9 | -46 00 38 | 17 700 ![]() |
15.76 | 0.6 | <7.0 | 4.7 | 235.3 | 10.63 | <11.0 | <2.1 | |||
C-67 | ESO 75-G55 | 22 06 24.9 | -67 31 03 | 14.93 | 1.0 | 3541 ![]() |
173 | 193 | 3.3 | 3.0 | 45.2 | 9.53 | 9.20 | 0.47 | |
C-68 | PGC 127657 | 22 24 14.5 | -66 02 18 | 14.73 | 0.9 | <4.6 | 5.0/5.2 | <0.54 | |||||||
C-72 | ESO 240-IG16 | 23 44 48.1 | -49 06 41 | 13 664 ![]() |
15.88 | 0.6 | <4.6 | 4.1 | 179.0 | 10.35 | <10.5 | <1.6 | |||
Notes: most optical data are mean, corrected values from the LEDA database; data in parentheses are literature values, from NED. For the estimated upper limits to | |||||||||||||||
the integrated H I line flux,
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for details on this object, and on the detections marked as "confused'' or "marginal'', see Sect. 4.1. |
Columns in Table 1 are as follows:
(1) galaxy number in the PRC,
(2) identifications in other catalogues,
(3 and 4) optical centre position, which was used as pointing position for the H I observations,
(5) optical systemic velocity and its estimated uncertainty, if available,
(6) the total blue magnitude, uncorrected for Galactic or internal extinction,
(7) blue major axis diameter at the 25 mag arcsec-2 isophotal level,
(8) centre velocity of the H I profile and its estimated uncertainty (see below),
(9) width of the H I profile measured at the 50% level of the peak flux density,
(10) idem, at the 20% level,
(11) integrated H I line flux or an estimated 3
upper limit (see below),
depending on the blue luminosity of the objects, if known (see text),
(12) rms noise level of the spectrum; if two values are listed for an object, the first refers to
the
-1000 to 12 000 km s-1 velocity range and the second to the
8500 to 21 500 km s-1 range,
(13) distance, derived preferably using heliocentric systemic H I line velocities, or otherwise
optical velocities, corrected to the Local Standard of Rest following the prescription of
Sandage & Tammann (1981, RSA):
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(1) |
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(2) |
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(3) |
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Figure 2: Parkes 21-cm H I line spectra of all clear and marginal detections. Each galaxy is identified by its PRC number. The axes are heliocentric velocity in km s-1, and flux density in mJy. The velocity resolution of the spectra is 13.2 km s-1, except for C-11 (6.6 km s-1) and C-14 (26.4 km s-1). |
Open with DEXTER |
PRC | Tel. |
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W50 | W20 | Ref. |
code | km s-1 | Jy km s-1 | km s-1 | km s-1 | ||
A-05 | P | 2880 | 19.5 | 221 | 240 | * |
P | 2910 | 220 | Ba97 | |||
G43 | 2909 | 23.2 | 244 | Ri94 | ||
V | 2910 | 16.0 | 231 | 243 | vG87 | |
AT | 2905 | 23.1 | 221 | 240 | Ar97 | |
C-11 | P | 396 | 32.1 | 79 | 112 | * |
P | 387 | 38.0 | 116 | Re82 | ||
P | 387 | 26.0 | Bo88 | |||
G43 | 404 | 32.4 | FT81 | |||
G43 | 394 | 37.4 | 113 | Ri94 | ||
IAR | 370 | 35.1 | 80 | 103 | BM85 | |
V | 406 | 30.6 | Co00 | |||
C-14 | P | [5141 | 2.1 | 241 | 241] | * |
P | <10.4 | Ha81 | ||||
G43 | 4775 | 26.2 | 678: | Ri94 | ||
C-42 | P | 3202 | 12.7 | 343 | 377 | * |
P | 3289 | 15.6 | 356 | 403 | Aa89 | |
G43 | 3242 | 7.7 | 401 | Ri94 | ||
Telescope codes: | ||||||
AT | Australia Telescope | |||||
G43 | Green Bank 43-m | |||||
IAR | I.A.R. 30-m | |||||
P | Parkes 64-m | |||||
V | VLA | |||||
References: | ||||||
Aa89 | Aaronson et al. (1989) | |||||
Ar97 | Arnaboldi et al. (1997) | |||||
BM85 | Bajaja & Martin (1985) | |||||
Ba97 | Barnes et al. (1997) | |||||
Bo88 | Boissé et al. (1988) | |||||
Co00 | Côté et al. (2000) | |||||
FT81 | Fisher & Tully (1981) | |||||
Ha81 | Hawarden et al. (1981) | |||||
Re82 | Reif et al. (1982) | |||||
Ri94 | Richter et al. (1994) | |||||
vG87 | van Gorkom et al. (1987) | |||||
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this paper |
Kinematically-determined polar-ring galaxies
A-05 (=NGC 4650A): this is probably the best-studied of all
polar ring galaxies, see, e.g., Arnaboldi et al. (1997).
Detected in the present survey and in 4 others,
including two interferometric mappings (see Table 2). The VLA and Australia Telescope
H I imaging show that our single-dish spectrum is not confused by the two other
relatively bright, but early-type galaxies in the Parkes beam,
NGC 4650 (
km s-1) and NGC 4650B (
km s-1).
These early-type galaxies are expected to be gas-poor
B-19 (= AM 2020-504): this is the best-studied case of a polar ring around an
elliptical galaxy (Arnaboldi et al. 1993a); the other case in our sample is PRC C-42,
see below.
The polar ring shows a gentle warp and is probably stable, giving time to stars to
form and grow old.
It has a UV spectrum typical of a starburst galaxy (Arnaboldi et al. 1993b).
The object was detected in the present survey, at
km s-1. Our profile does not seem to be confused by another
object in the beam.
The H I line velocity corresponds well to the mean optical
value of the PRC object,
km s-1 (LEDA).
Just outside the telescope's FWHM radius, two galaxies lie at about 8' distance
from the PRC target: the quite face-on (b/a=0.8) 14.0 mag Sc type spiral ESO 234-G016
at
km s-1 and the 14.6 mag Sbc type spiral ESO 234-G017, of
unknown redshift. Given the difference in optical velocities (225 km s-1) and the range
of velocities in our H I profile, it seems unlikely that the Parkes profile was
confused by ESO 234-G016.
Good candidates
B-02 (= PGC 419347): this object does not have a known optical redshift.
We detected an H I profile towards it, at
km s-1.
At 7
3 distance, around the telescope's FWHM radius,
lies 15.5 mag Sc? type spiral ESO 151-G37, with
km s-1
(Mathewson & Ford 1996), 91 km s-1 higher than the H I value.
If the detection were in fact entirely due to ESO 151-G37, its integrated
H I line flux would be
3.4 Jy km s-1, at
50% beam efficiency, implying an
ratio of 0.8
/
.
Such a ratio is about 2.5 times the average for
Sc spirals (Roberts & Haynes 1994) and therefore highly unlikely.
If, on the other hand, all H I were to be due to B-02 alone, its
ratio would be 1.4
/
,
a quite common value for an object
from PRC Category B. A long-slit H
spectrum of ESO 151-G37
(Mathewson & Ford 1996) shows a maximum rotational velocity, uncorrected for
inclination, of 107 km s-1, much larger than half the W50 width of our H I spectrum,
45 km s-1.
In conclusion, it is not very likely that our H I detection may be confused by
nearby ESO 151-G37.
B-06 (= AM 0442-622): detected in the present survey, at
km s-1. The only other catalogued galaxy within the telescope's FWHM,
the low surface brightness object LSBG F118-043, of unknown redshift
and
18.7 mag. Though low surface brightness galaxies can be quite gas-rich,
it is
2.4 mag fainter than B-06 in the blue, and hence not a likely candidate
for confusion with our H I profile. The
ratio of 1.4
/
derived
for B-06 assuming that all detected gas resides in it is a quite common value
among the PRC Category B objects.
B-18 (= AM 1934-563): detected in the present survey, at
km s-1, with a W50 width of 193 km s-1.
Its nuclear H
and [N II] emission lines
(Reshetnikov et al. 2001) indicate fast rotation of the gas in the
innermost regions, reaching a projected rotational velocity of
230 km s-1 at
2'' from the nucleus, as well as signs
of Sy2 or LINER activity.
Its mean optical systemic velocity listed in LEDA, 11
km s-1,
did not take into account the latter two of the four following
published redshifts: 11
km s-1 (Fisher et al. 1995),
11
km s-1 (Allen et al. 1991),
11
km s-1 (Fairall & Jones 1991) and
11
km s-1 (Reshetnikov et al. 2001).
From these three values, we derive a weighted mean value of
km s-1, 367 km s-1 (
6
)
lower than the H I value, a significantly large difference.
Three galaxies of similar size and magnitude can be seen
in Fig. 1, which appear to form a triplet.
Besides the PRC object, these are PGC 399718 (
and D25 = 0
7)
and PGC 400092 (
and D25 = 0
5), both of unknown redshift.
The
ratio of 1.5
/
we would derive for B-18 if all
H I were concentrated in it is quite common for a PRC Category B object,
however.
In conclusion, we cannot exclude that the H I profile may be confused with,
or due to, another member of the triplet.
B-27 (= ESO 293-IG17): not detected in the present survey. Our Green Bank H I survey (Paper I) did not cover the optical redshift of the object (15 300 km s-1), which was published afterwards.
Possible PRG candidates
C-07 (= ESO 113-IG4): an H I line was detected in the present survey,
at
km s-1.
The optical systemic velocity, 3130 km s-1 (from Keel 1985), is 477 km s-1 lower
than the H I value. Though its uncertainty is listed as 35 km s-1 in LEDA, a value of
200 km s-1 was quoted in Keel's paper - we adopted the latter uncertainty.
Given the relatively large uncertainties involved, the H I and optical velocities
may be consistent.
No candidates for confusion with our H I spectrum were found within the search area.
C-08 (= ESO 243-IG19): detected in the present survey, at
km s-1.
No optical redshift is known of this object.
No candidates for confusion with our H I spectrum were found within the search area.
C-11 (= NGC 625): detected in the present survey and in 6 others (see Table 2), with good agreement between the global H I line parameters measured at different telescopes and in different studies. The galaxy was mapped in H I at the VLA (Côté et al. 2000), where a peculiar gas distribution and kinematics was found. The H I is rotating around the optical major axis, rather than the minor axis, though its distribution is elongated along the major axis - contrary to the situation in polar rings. Multiple velocity peaks occur at many places in the VLA data. Consequently no H I rotation curve could be derived. The ionized gas in the galaxy also follows complex orbits (Marlowe et al. 1997), which do not match the H I kinematics, however. It is a rather red system ( B - R) = 0.89, with a smooth morphology reminiscent of lenticular galaxies, and strong emission lines, like a blue compact dwarf (Skillman et al. 2002) According to Côté et al., the seriously disturbed nature of NGC 625 is due to a major merger event rather than a case of bad digestion of an accreted H I cloud.
C-14 (= NGC 979): No optical velocity is known of this object,
and it does not appear to have been detected in H I.
A detection with the Green Bank 43-m telescope was reported
in Paper I, with a centre velocity of 4775 km s-1, an exceptionally large width
of
W20=678 km s-1 and a peak flux density of 30 mJy, while
at Parkes no line signal was detected by Hawarden et al. (1981), with
a published upper limit to the integrated H I line flux of 10.4 Jy km s-1.
As no trace of the signal seen at Green Bank can be found in our Parkes data,
which have an rms noise level of 3.3 mJy, it must have been due to interference.
Our Parkes spectrum shows a marginal H I
detection at
km s-1, which is likely to be associated with ESO 246 G-22,
a 14.4 mag SBc spiral with an optical redshift of
km s-1 (LEDA), 9
1
from the PRC object. We therefore consider PRC C-14 to be undetected in our
survey, and the upper limit to its
ratio of 0.22
/
listed
in Table 1 was estimated using a 300 km s-1 linewidth, like for all objects
of unknown redshift.
C-15 (= ESO199-12): A strong H I line was detected in the present survey,
with
km s-1 and
W50=409 km s-1.
There appears to be a faint detection in the Parkes HIPASS survey data, at
7000 km s-1,
with a peak flux density of about 30 mJy, like in our spectrum.
The large uncertainty in the optical velocity of the object, as listed in LEDA,
km s-1, is due to one discrepant measurement:
km s-1 (Kirhakos & Steiner 1990),
compared to the
and
: km s-1 from, respectively, Da Costa et al. (1991) and
Chincarini et al. (1984). Therefore, the optical redshift is rather
km s-1,
157 km s-1 (i.e., 2.5
)
higher than the H I value.
The only other galaxy of significant size (D25 = 1
2) within the telescope's FWHM
is IC 1877, an edge-on Sb:pec spiral of unknown redshift and
16.2 mag.
It does not seem likely that this 1.4 mag fainter object would cause serious confusion
in the H I spectrum of the target object. The
ratio of 1.25
/
we would
derive if all H I was concentrated in the PRC object is not uncommon for PRC category-C objects.
C-16 (= AM 0320-495): our Parkes spectrum only shows an off-beam detection of an
unidentified galaxy, with
km s-1,
W50=207 km s-1 and
2.1 Jy km s-1.
It appears to be a sidelobe-detection of
13.6 mag, Scd spiral IC 1914, at 27
3
distance from the target object. Observations of IC 1914 at Parkes by
Longmore et al. (1982) show
km s-1,
W50=206 km s-1 and
Jy km s-1.
C-20 (= ESO 201-IG26): detected in the present survey, at
km s-1,
corresponding well with the optical systemic velocity of
(LEDA). Also in, the
less sensitive, Parkes HIPASS data a tentative detection is seen at the same velocity.
No candidates for confusion with our H I spectrum were found within the search area:
at 2
4 distance, low surface brightness object LSBG F202-064,
of unknown redshift and
17.7 mag, does not seem a likely candidate:
though low surface brightness galaxies can be quite gas-rich,
it is
2.2 mag fainter than C-20. The
ratio of 0.95
/
derived
for C-20 assuming that all detected gas resides in it is a quite common value
for a PRC Category C objects.
C-22 (= ESO 202-G1): in our present survey no H I line is seen at the optical velocity,
10
km s-1 (LEDA; based on 2 published values), while a tentative line signal is
seen at
km s-1, with
W50=220 km s-1 and
Jy km s-1.
Though no candidates for confusion with our H I spectrum were found within the search area,
we cannot be certain that the object was detected, seen the weakness of the tentative line
detections and the difference of 272 km s-1 (i.e., 5.5
)
between the
well-established optical redshift and our H I value.
We have therefore marked the spectral line as "marginal'' in Table 2, and we did not
derive an H I mass from it.
C-42 (= NGC 4672): it has an elliptical stellar core rotating perpendicularly to
the disk and appears to be the end result of the accretion of material in polar orbits
in a disk around a pre-existing oblate spheroid, like in the prototype PRC B-19
(Sarzi et al. 2000).
The object was detected in the present survey, at
km s-1, as well
as previously at Parkes and at Green Bank (see Table 2) at similar velocities, which are
all consistent with the mean optical systemic value of
km s-1 (LEDA).
The integrated line flux of 7.7 Jy km s-1 measured at Green Bank (Paper I) is significantly lower
than the 12.7-15.6 Jy km s-1 found at Parkes (Aaronson et al. 1989, and the present paper).
No candidates for confusion with our H I spectrum were found within the search area:
though NGC 4677, a 13.9 mag object at 10
7 distance, has a velocity of
km s-1 (LEDA), similar to that of the PRC object, it is well outside the telescope's FWHM and classified
as SB0 and therefore expected to be gas-poor.
C-48 (= ESO 326-IG6): not detected in the present survey, nor in our Green Bank survey (Paper I), with an almost two times higher rms noise level of 9.5 mJy.
C-52 (= ESO 232-G4): detected in the present survey, at
km s-1.
Its published optical systemic velocities are
km s-1 (Reshetnikov et al. 2001),
based on faint lines, and
km s-1 (Fairall 1984), a rather uncertain value.
Seen the uncertainties, these values may be consistent with the H I value.
Its nuclear spectrum was tentatively classified as LINER: by Reshetnikov et al. (2001).
No candidates for confusion with our H I spectrum were found within the search area.
C-53 (= IC 4982): detected in the present survey, at
km s-1.
No object is visible on the DSS at the position
given in the PRC, 20
15
22
4, -71
11'13'' (B1950.0);
the galaxy identified as C-53 in Fig. 2 in the PRC is
actually IC 4982, 1
9 NW of the C-53 position. We therefore
used the optical position of IC 4982 as our pointing centre at Parkes and
listed its optical characteristics in Table 1.
No candidates for confusion with our H I spectrum were found within the search area:
IC 4985, 2
4 NE of the target object is a 14.8 mag S0 galaxy at a quite
different redshift of
km s-1 (LEDA), and expected to be gas-poor.
C-55 (= ESO 143-G37): detected in the present survey, at
km s-1.
The HIPASS data show an H I detection similar to ours.
No candidates for confusion with our H I spectrum were found within the search area:
no data are available for the small galaxy pair AM2033-620 at 6
2 from the
target object.
C-56 (= PGC 128148): detected in the present survey, at
km s-1.
No candidates for confusion with our H I spectrum were found within the search area.
C-67 (= ESO 75-G55): detected in the present survey, at
km s-1.
No candidates for confusion with our H I spectrum were found within the search area.
Acknowledgements
We are grateful to the ATNF staff at the Parkes observatory and in Epping for their assistance with the observations and data reduction. The Parkes Telescope is part of the Australia Telescope, which is funded by the Commonwealth of Australia for operation as a national facility managed by CSIRO. This research has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration and the Lyon-Meudon Extragalactic Database (LEDA). WvD acknowledges the financial support of the ASTE of INSU for the observations at Parkes.