К вопросу о новоподобных звездах типа U Geminorum / On the Nova-like stars of the type of U Geminorum

Gordeladse, Sh.G. and გორდელაძე, შ. and Горделадзе, Ш.Г. (1938) К вопросу о новоподобных звездах типа U Geminorum / On the Nova-like stars of the type of U Geminorum. აბასთუმნის ასტროფიზიკური ობსერვატორიის ბიულეტენი / Bulletin of the Abastumani Astrophysical Observatory (3). pp. 92-102.

[img]
Preview
Text
1938-I-10.pdf

Download (2MB) | Preview

Abstract

The variables of U Geminorum type represent the most interesting objects among the Nova-like stars as those shoeing the peculiar characteristics inherent to Novae in general. The rapid increase to maximum followed by a somewhat slower decrease of brightness is similar to that of typical Novae. Besides, the spectrum of those stars show at maximum and after it the peculiarities quite characteristic of typical Novae, i. e., the displacement of lines indicating the outflow of gas particles from the star's, surface with a velocity of the order of 1000 km/sec. Therefore, the stars of U Geminorum type justify wholly the appelation of "Novae on a small scale". Although the amplitude of brightness variation of U Geminorum type stars (about 4-5 stellar magnitudes) is not so large is, for instance, that of typical Novae, the above mentioned peculiarities give ground to suppose that in the process of successive outbursts of the stars of U Geminorum type certain phenomena are occuring similar to those accompanying the outbursts of typical Novae. Therefore, we may suppose that during the outbursts of those stars the outflow of mass is taking place. The object of the present article is to estimate the amount of the mass outflow during each outburst and to determine in what manner it will be related to the values of the mass outflow during the outbursts of typical Novae. For this purpose we make use of the formula (1), where is the mass outflow, A -a constant for the given star, while the function φ (t) is represented by (2), L(star) and L(sun) being the brightness of the star and the Sun, respectively. In the formula (1) the interval of integration corresponds to the interval of time during which the outflow of gas is taking place. It is to see from the expression (2) that in order to determine the amount Of the mass outflow it is necessary to know the absolute magnitude of the given star at maximum. However, the available experimental material on the brightness variation of U Geminorum type stars does not contain any data on their absolute magnitudes at maximum, the visual magnitudes alone being given; in general there are no data on the absolute magnitudes of the most stars of this type. It is, therefore, much more convenient to modify the formula (2) in order to acquire the possibility of using directly the available empirical material. Evidently, we may write (3), where M(sun) and M(star), are the absolute magnitudes of the Sun and the star, respectively. Farther, we have (4), where m(star) is the visual magnitude of the given star. Taking into account (2), (3) and (4) we obtain definitively for the mass outflow (5), where Δt is the width of the maximum or the interval of time during which the outflow is supposed to take place, m(star) is the visual magnitude of the star at maximum and C—a certain constant defined by the equation: C= 1.5(log r—0.03)+ log A, the value of which for the convenience of calculation we accept to be equal to 2.5. It may be seen that the formula (5) is a modification of (i) the sole difference being that the value.of the mass is given in relative units, instead of absolute ones, this being quite sufficient for statistical examination of the experimental material. We applied this formula to the data on the star SS Cygni and obtained Table 1. For different elements of this Table the same notation has been used as in the work referred to above, while M is the mass outflow during a given outburst. We refrained from the attempt to establish the correlation between the values of the mass and the different characteristic elements and we postponed the use of the correlation method till to the moment when the data of a similar character will be available also for other stars of the same type. We determined only the frequency for different values of mass. Farther, taking into account that the mass outflow during the outburst of typical Novae amounts to about 10^29 gr, we derive that the stars of U Geminorum type, in particular SS Cygni, lose in about 5000 years the same quantity of the mass as any of typical Novae loses during a single outburst, considering that the outbursts of these stars occur about 10 times in the year. The same figures are obtained for the star U Geminorum its absolute magnitude at maximum being evaluated to 5.2. March, 1938

Item Type: Article
Subjects: Q Science > QB Astronomy
Divisions: Institutes > Evgeny Kharadze Abastumani National Astrophysical Observatory
Depositing User: თამარ ჭაღიაშვილი
Date Deposited: 09 Jul 2018 10:23
Last Modified: 09 Jul 2018 10:23
URI: http://eprints.iliauni.edu.ge/id/eprint/8171

Actions (login required)

View Item View Item