Preliminary results obtained with the technique in its standard version were already presented elsewhere (Carbillet et al. 1996b). We give here a more accurate application of the technique in its two versions to three binary stars for which the observing conditions are reported in Table2. All the data reduced in this section consist of high-light level speckle frames of pixels. We give in what follows a detailed description of the analysis for each object.
Figure 6: Top: linear gray-level representation of a) and c), together with plots of the corresponding radial integrations-- b) and d) --for the binary Del. Middle: Q a) and c), and the corresponding radial integrations-- b) and d) --for the binary Moaï 1. Bottom: the same as in Top for the binary Per
|star name||r.a. 2000.0||dec. 2000.0||mR||Telescope||<r0>||Date|
|Del||3.2||2m BLT||6580/425||cm||20 ms||11/09/94|
|Moaï 1||6||2m BLT||6500/700||cm||20 ms||12/12/95|
|Per||2.3||4.2m WHT||6580/425||cm||25 ms||19/01/95|
The subgiant Del is a close binary of 26.6 years of period given as a standard star for binary-star interferometry by McAlister & Hartkopf (1983). The latest orbit is computed by Hartkopf et al. (1989). The reference star observed was Del from which we used 410 frames, and 324 for the binary.
The separation angle d and the PA from which we derived an estimation of were computed from the classical calculation of the visibility function, founding: and .
Figure 6 (click here), first row, shows both the quantities and , with their radial integrations and , derived from the twofold PDFs of the binary and of the reference star computed for the space-lag vector , and from the twofold PDF of the binary computed for . From these quantities, we could deduce the value of for which they are extrema by the procedure described in Sect. 5 (click here). So we have: using the standard version; or: using the reference-less version. The exact value of the intensity ratio, giving then both the orientation and a relative photometry of the binary system, is found to be (or ), that corresponds to a magnitude difference (or ). This is in agreement with the value given by Couteau (1962)-- i.e. 0.9 --if one considers that is roughly similar to for this object. Moreover, since we found an intensity ratio smaller than 1, we can assume, given the orientation of the frames and , that PA is 288 and not 108. This is anyway what was expected from the orbit cited before.
It is interesting to note that the two versions of the method give, for these data, an equivalent result, even if the relevant ridge seems to be better defined using the reference star data.
The close double star Moaï 1 (SAO12917) was discovered during the observation from which the data used in this section are extracted. The approximate period evaluated by Carbillet et al. (1996c) is years. The separation vector was deduced from this last paper using the cross-correlation technique (Aristidi et al. 1996). This corresponds to: and . The reference star observed was SAO12929 from which we used 2617 frames, and 2619 for the binary.
Figure 6 (click here), second row, shows both the quantities Q and , with their radial integrations IQ and . The value of derived from these quantities is: -- or . The deduced value of is then: (or ), that corresponds to a magnitude difference: (or ). This is in agreement with the value computed in the paper cited before and using both the cross-correlation technique and the fork algorithm (Bagnuolo 1988)-- and . The position angle is then confirmed to be: and the magnitude difference between the companion and the primary star in the red: .
We can say that, here again, the method seems to take advantage of its use with the data of the reference star, the reference-less method giving anyway an acceptable value of the intensity ratio.
Per is a giant eclipsing binary star of 17.8 years period whose orbit can be found in Hartkopf et al. (1996). The reference star observed was Per from which we used 752 frames, and 443 for the binary. The separation and position angle computed from the visibility function were: and .
Figure 6 (click here), third row, shows both the quantities and , with their radial integrations and . The value of derived from these quantities is: -- or . The deduced value of the intensity ratio is then: (or ), that corresponds to a magnitude difference: (or ). This first shows that the right position angle is 62 and not 242. Moreover, the absolute value of found is in agreement with the early speckle interferometric measurement of Labeyrie et al. (1974) that estimated a of 1-2 mag for a wavelength of Å. More precisely, McAlister et al. (1982) estimated in the red to be at least greater than 1.4 mag, the estimated .