Up: CCD astrometry and instrumental stars
We present our results in Table 3.
The first two columns contain the coordinates of the primaries
for epoch 2000. Next column contains
the Durchmusterung designation of the primaries as listed in WDS
(Worley & Douglass 1984).
The next two columns contain the observed instrumental magnitude difference
between the two components of the binary and its accuracy,
and
.The following four columns contain angular separation
,
its accuracy
in arcseconds, and the position angle
with its accuracy
in degrees.
All accuracies of the mean values always refer to four consecutive
exposures of the same binary.
The last column contains the epoch of the observation in years after 1900.0.
Table 3:
Common proper motion binaries in our sample
 |
The histogram of
Fig. 4
![\begin{figure}
\includegraphics [angle=-90,width=7cm,clip]{ds8188f4.ps}\end{figure}](/articles/aas/full/1999/09/ds8188/Timg30.gif) |
Figure 4:
Absolute values of differences in angular
separations since the detection of the binary |
![\begin{figure}
\includegraphics [angle=-90,width=7cm,clip]{ds8188f5.ps}\end{figure}](/articles/aas/full/1999/09/ds8188/Timg31.gif) |
Figure 5:
Absolute values of differences in position
angle since the detection of the binary |
shows that 33% of the 83 observed binaries
have an angular separation different by less than
or 5%
of the initially observed -at the epoch of the detection of the binary-
angular separation several
decades ago. Additional 29% show changes in the range of 5% to 10%.
(
).
Most of them (73 or 88%) show
.Taken into account that WDS lists
with
a precision of 0.1 arcseconds and that the first double star
observation is several decades old or even from last century
-thus less accurate due to the technology used-, most
of our targets show practically even now the same angular separation
as at the epoch of their detection.
Similarly, Fig. 5
shows that 36% of them change their position
angle less than
(the precision of the position angle
listed in WDS) in all these decades since their detection.
Furthermore, 57 of them (or 70%) show
.
Table 2 shows 12 double stars in the sample which
show almost the same relative positions as at the epoch
of their detection.
The first column contains the BD number of the primary,
columns two and four the angular separation and the position
angle of the components at the epoch of the detection as
listed in WDS. This epoch is shown in column six.
Finally, corresponding relative positions of the present
work are listed in columns three and five respectively.
Since the epoch of double star detection listed in column six is
usually many decades ago, these double stars must be
common proper motion double stars and thus
very strong candidates to be physical binaries. More astrophysical
data should be gathered on them; we will be able to execute a
photometric programme to this purpose thanks to the availability
of the Kryonerion telescope.
Acknowledgements
This research was partially carried out in the framework
of the project "Pôles d' Attraction Interuniversitaires'' P4/05,
initiated and financed by the Belgian Federal Scientific Services
(DWTC/SSTC).
Up: CCD astrometry and instrumental stars
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