The color-magnitude (CM) diagrams for Car OB1 and Car OB2 fields are
presented in Fig. 2 (click here). All stars from Table 2 of this paper, uvby
data for the Car
OB2 association (Table
2b, Kaltcheva & Georgiev 1993) and the stars from Table 4 are included to construct these
diagrams. This sample is about 90% complete concerning the limited magnitude and
spectral type mentioned above.
There are clearly recognizable main sequences (MS) in both
diagrams. Also a presence of evolved stars and presence of foreground stars can be seen.
The foreground stars should be responsible for the appearance of the "second main
sequences" on the CM diagrams, which usually correspond to groups at different distances.
It is of interest to see the differences in the spatial distribution between the MS stars and the
other stars of the sample.
Figure 2: Color-magnitude diagrams for Car OB1 and Car OB2 fields
Figure 3: The obtained distances and color excesses for the program stars as functions of
Galactic longitude. The meaning of the symbols used are the same here and for
Fig. 4 (click here).
The stars that form the main sequences in the CM diagrams in the
Fig. 2 (click here) are marked with "open'' symbols. All of them are more distant than 1200 pc in the direction of Car OB1
and 1600 pc in the direction of Car OB2. The stars that are more
evolved according to the HR diagrams are marked with "filled" symbols. All of them are more distant than 1600
pc. "+'' symbols are used for the stars that are non-MS according to the CM diagrams and
low-massive according to the HR diagrams. All of them are nearer than 1600 pc
Figure 4: Hertzsprung-Russell diagrams for Car OB1 and Car OB2 fields. Theoretical tracks
are from Maeder & Meynet (1988).
The symbols are the same as for Fig. 3
The derived distances and color excesses for each star are plotted as functions of the Galactic longitude in Fig. 3.
The Hertzsprung-Russell (HR) diagrams for the
Car OB1 and Car OB2 fields are shown in Fig. 4 (click here). To build the HR diagrams, the bolometric
corrections from de Jager (1980) are used for the calculation of the luminosities. For III-V
luminosity classes, the effective temperatures were obtained from the relation 
/c0 of
Code et al. (1976). For supergiants, the linear relation
between and (u-b)0 obtained from the tables 
(Bohm-Vitense 1981) and (u-b)0/Sp (Zhang
1983) are used. The theoretical tracks plotted in these figures are
from Maeder & Meynet (1988).
The stars that form the MS in CM diagrams form a very tight main sequence in HR
diagrams for both fields. They are marked with "open" symbols in Figs. 3 and 4.
According to the distances obtained here, all MS stars are more distant than 1200 pc in the Car
OB1 direction and more distant than 1600 pc in the Car OB2 direction. Probably all of them
are connected with the Carina Arm. The majority of them are concentrated at 
and
.
"Filled" and "plus" symbols are used for marking of the non-MS stars. According to the distances obtained, the non MS-stars are both nearby and situated at the Carina Arm. All objects nearer than 1600 pc are low-massive main-sequence objects according to their positions in the HR diagrams. They are marked with "+" symbols in both figures. The distant stars are more evolved and not very massive, according to their positions in the HR diagrams. All of them are more distant than 2100 pc and spread over distances to 6000 pc. They are marked with "filled" symbols.
Figure 3 indicates a link between the Local Arm and the Carina arm at the direction 
. The increase of the color excess at this direction seems to be a characteristic of the
Local arm.
The stars from Table 5 are not included in the analysis because of the different distance calibration used. For these stars, the obtained distances cover a rather wide interval and the corresponding diagrams remain the same concerning grouping.