The photoelectic photometry of the eclipsing variable 44 I BOO B in the infra-red and violet regions of the spectrum

Nikonov, V.B. and ნიკონოვი, ვ. and Никонов, В.Б. (1940) The photoelectic photometry of the eclipsing variable 44 I BOO B in the infra-red and violet regions of the spectrum. აბასთუმნის ასტროფიზიკური ობსერვატორიის ბიულეტენი / Bulletin of the Abastumani Astrophysical Observatory (4). pp. 1-15.


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The observations of the eclipsing variable 44i Boo B are a part of the test work of some new types of photocells carried out in order to show their applicability for stellar photometry. The very short period of 44i Boo B gave the possibility to cover the whole light curve during a single night. This was very essential because of the small number of photometrically good nights in the given season- The considerable brightness of 44 i Boo B gave also a good possibility to test the cells on the existence of any fatigue-effect. It was also of great interest to secure observations of 44 i Boo B with photocells of new types (stibium-caesium and caesium-oxide ones) since it made possible to get light curves of the star for remote regions of spectrum. The star 44i Boo B, an eclipsing variable of the W Ursae Majoris type, was discovered by Schilt alter full analogy of its spectrum with that of WUMa had been stated. As it is known, 441 Boo B is a fainter component of the visual binary 2 1909 = ADS 9494. The visual magnitude of 44i Boo B in the Harvard system is 6m.i, and the magnitude of the brighter component 44i Boo A is 5m.3. The star has been studied by Schilt as well as by Kuiper, Rybka, Huffer, Shapiey and Calder. 44 i Boo is a very interesting visual binary with one variable component. The orbital motion of the variable will cause a periodic change in the observed moments of its primary minimums (or in the apparent period), thus giving an equivalent of a spectroscopic orbit of the star. Thus it is very interesting to observe the moments of the primary minimums of the eclipsing 44i Boo B. Shapley and Calder when observing this star photoelectrically, found also any changes in the light curve of the variable. All these circumstances make further photoelectric observations of 44i Boo of great interest. It may be noted that owing to a very small angular distance between the components 44 i Boo A and 44i Boo B one has to confine oneself in photoelectric observations'to the determination of the total brightness of the whole system (A + B). This was the case in Shapley—CaIder's observations as well as in ours. We carried on our observations with two sample of photoelectric cells under testing. The first was a gasfilled caesium-oxide photo-cell. The dark current of this photoc-ell, having a very high infra-red sensitivity, equals only 3.10^-14 A at the room-temperature. It may be noted that in the beginning of our observations of 44 i Boo we had no sufficient accelerating potential at our disposal. We had used only a 150 V battery, the glow potential of the cell we used being at 450 V. Later, when we got the possibility of raising the accelerating potential up to 326 V the absence of necessary power supply at that time made it impossible to evacuate the photo-cell-box of our photometer. This, naturally, led to the decrease of steadiness of the amplifier and obliged us to lower its sensitivity-All these circumstances caused the observations of 44i Boo with the caesium-oxide photo-cell being carried on in conditions corresponding to observations of considerably fainter stars. This inevitably lowered the precision of our observations. The identity of the curves for quite different regions of the spectrum shows that in case of the star 44 i Boo B we have a perfect similarity of the structure of both components of the variable. It presents some difficulties to obtain good orbital elements of 44 i Boo B on the base of photoelectric observations because of the necessity of excluding the light of the star .|p Boo A. It requires special determination of its brightness with a long focus instrument in the same color-system in which the photoelectric observations were made. In conclusion I wish to record my thanks to Dr N. N. Pavlov from Poulkovo Observatory for his kindly placing at my disposal the stibium-caesium photo-cell for the present photometric test. August, 1939.

Item Type: Article
Subjects: Q Science > QB Astronomy
Divisions: Institutes > Evgeny Kharadze Abastumani National Astrophysical Observatory
Depositing User: თამარ ჭაღიაშვილი
Date Deposited: 11 Jul 2018 11:21
Last Modified: 11 Jul 2018 11:21

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