3. Results and discussion

Figure 2 (click here) shows a grey scale map of the flux densities taken from the IRAS Sky Survey Atlas (Wheelock et al. 1991), using the software provided by Sky View (http://skview.gsfc.nasa.gov/skyview.html). Also shown in this figure is the distribution of our 1346 new galaxy candidates. As can be seen, similar to the results in our previous work, the IRAS flux densities can serve as a rough indicator for galactic extinction also in this region. A result which is confirmed in a more elaborate way by Gajdošık & Weinberger (1997). The flux density distribution seems to account for the overall distribution of the galaxies.

The most striking feature in Fig.2 (click here) is the pronounced asymmetry both in the distribution of the galaxies and in the IRAS flux densities. There are 1136 galaxies located to the south of the galactic equator, whereas only 15.6% of all galaxies can be found in the northern part. An investigation of the diameters leads to the result that the southern galaxies, on average, exhibit larger projected sizes. This gives us further evidence that the asymmetry in distribution might be caused by a south-north extinction gradient within our galaxy (see Cameron 1990). The observed asymmetry is most probably caused by the galactic warp which is expected to exhibit a maximum north to the galactic plane at (Henderson et al. 1982; Miyamoto et al. 1988; Djorgovski & Sosin 1989; Freudenreich et al. 1994).

 
Figure 2:   Top: distribution of the new galaxies in the region , in galactic coordinates. Bottom: the flux density taken from the IRAS Sky Survey Atlas; black (white) areas correspond to low (high) flux densities. Both parts of the figure represent the same region

An additional and interesting feature is located in the region studied here. A branch of the PPScl is approaching the ZOA at , from the south. By means of 21cm measurements Seeberger et al. (1994) have traced this branch until . If this feature penetrates deeper into the ZOA, its further route cannot be estimated from our galaxy distribution. It might remain straight to the north-west (with respect to the galactic coordinates) within the ZOA. In this case it would, if it really penetrates the ZOA, best be recovered at , . To investigate this feature we have selected a sample of galaxies at the northern and southern parts of the ZOA and measured their radial velocities. To determine the velocities we have used absorption lines and, where available, lines which appear in emission. The errors of these measurements are estimated to be less than .

The names and coordinates of these galaxies, mainly chosen at the southern part of the ZOA, together with our results are listed in Table1 (click here). For the literature search we have made use of the Simbad database and the NASA/IPAC Extragalactic Data-base (NED). For 14 galaxies Table1 (click here) gives heliocentric radial velocities measured for the first time, according to these databases.

Galaxies of the PPScl typically exhibit velocities of (see, e.g., Haynes & Giovanelli 1986). An inspection of Table1 (click here) shows, that galaxies of our sample only in the southern region () fit this condition, say within an error-range of , and can thus be regarded as possible members of the PPScl. Unfortunately, in the northern part () only very few galaxies (5) could be measured until now. However, all of these have velocities well above 5000km/s.

Finally, in Table2 (click here) our 1346 optical galaxy candidates are presented in detail. The whole compilation is available from the Simbad database. The first column gives the name of the galaxy. If the name is followed by a colon, the classification as a galaxy is less certain. Columns 2 and 3 (4 and 5) list the right ascension and declination 1950.0 (2000.0). Column 6 gives the designation of the POSS prints on which the object was found, and Cols. 7 and 8 the location of the object (x, y) in cm. In Cols. 9 and 10 (11 and 12) the maximum diameter of the galaxy candidate and, if visible, the diameter of the core on POSSI-E (POSSI-O (blue-sensitive)) can be found. All diameters are in arcmin. The last column gives cross-identifications. If we have found an IRAS point source within of radius around the object, the IRAS name was included in this column. If the IRAS name is followed by an asterisk, more than one galaxy candidate coincides with the position of this IRAS source.

As pointed out in our previous papers only a few percent of the optical galaxies turned out to have counterparts in the IRAS Point Source Catalogue. The size distribution function again indicates a complete size limited sample down to a diameter limit of .

 

name b ref # of

this other lines

MCG+08-36-010 81.64 9.47 8004 8081 ST92 7

CGCG 493-2 82.07 -15.08 7502 17

UGC 11507 83.70 9.71 6800 2

MCG+08-36-016 83.93 9.67 6900 7071 SA76 6

UGC 11775 83.94 -12.31 4426 4828 KA88 10

UGC 11772 83.95 -12.24 4494 4451 KA88 10

UGC 11781 84.31 -12.18 4317 4774 KA88 9

CGCG 257-36 85.57 9.62 7260 8

UGC 11757 87.70 -6.88 4234 4523 BO93 12

4351 HA91

MCG+06-47-007 87.75 -11.44 5221 11

UGC 11892 88.82 -15.55 5812 5638 WE93 9

UGC 11893 88.84 -15.36 5432 5564 WE93 7

UGC 11801 90.64 -7.25 3925 10

UGC 11798 90.64 -7.23 3841 3984 BO93 7

4029 HA91

4031 SE94

UGC 11797 90.64 -7.23 4214 4043 SE94 9

5572 SE94

G092.15-02.28 92.15 -2.28 3556 7

G092.17-02.29 92.17 -2.29 3727 3775 KE87 7

UGC 11800 92.42 -5.19 5335 5520 BO93 10

UGC 11805 92.52 -5.26 5455 5679 SE94 11

UGC 11804 92.52 -5.27 5645 5440 DA95 12

UGC 11911 94.47 -9.31 5018 5996 MA86 10

UGC 11997 97.27 -9.78 4508 9

UGC 11874 98.02 -2.84 656 9

UGC 12096 101.67 -6.97 10514 7

UGC 12095 101.67 -6.97 412 5

UGC 12089 101.74 -6.73 9446 10

UGC 12091 101.74 -6.73 9688 7

UGC 12223 103.83 -8.95 5330 10

G105.42+09.58 105.42 9.58 8226 8411 SE94 5

G109.75-08.40 109.75 -8.40 10291 9

Table 1:   Heliocentric velocities of a sample of galaxies. Given are the names, the galactic longitudes and latitudes, the heliocentric velocities as a result from this work and values found in the literature. The last column gives the number of absorption/emission lines used for determining the velocity for each galaxy

References to the table:
BO93: Botinelli et al. (1993)
DA95: Davoust & Considère (1995)
HA91: Haynes & Giovanelli (1991)
KA88: Karachentseva et al. (1988)
KE87: Kerr & Henning (1987)
MA86: Mazarella & Balzano (1986)
SA76: Sandage (1976)
SE94: Seeberger et al. (1994)
ST92: Strauss et al. (1992)
WE93: Wegner et al. (1993).

 

 

Table 2:   Optically detected galaxies in the region ,

Acknowledgements

We would like to thank Prof. R. Weinberger for his help and fruitful discussions. This work was supported by the "Fonds zur Förderung der wissenschaftlichen Forschung'', project No. P8325-PHY and by the "Jubiläumsfonds der Österreichischen Nationalbank'', project No. 4713 (computer facilities). This research has made use of the NASA/IPAC Extragalactic Data-base (NED) which is operated by Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration; and of the Simbad database, operated at CDS, Strasbourg, France.