Flare Colours and Luminosities

Abstract

Flare colours determined from simultaneous UBV observations made at Catania Observatory and from sequential UBV observations made at McDonald Observatory are presented. They fit fairly well with the theoretical colours computed according to the Gurzadian's (1970) non-thermal model. Only part of the observed flare colours are consistent with the solar type models by Gershberg (1967) and Kunkel (1970).From a B-band patrol of UV Cet-type stars carried out from 1967 to 1972, some quantitative estimates of flare frequencies and luminosities and of their average contribution to the stellar radiation are given.The corresponding parameters for the Sun, which were estimated from ‘white light’ flare activity, are also given for comparison. The Sun and V 1216 Sgr can be regarded as low-activity flare stars of the type found by Kunkel (1973).

Coordinated X-ray, optical, and radio observations of YZ Canis Minoris

“…Although there is evidence that the local flare stars may comprise an association (Arakelian 1970; Ambartsumian and Mirzoyan ].975), it will be assumed in this analysis that the flare-star space density in the Galaxy as a whole is the same as in the solar neighborhood. According to Kunkel (1970), Cristaldi and Rodono (1975) and Lacy, Moffett and Evans (1976) The diffuse soft x-ray background fluctuates only slightly with galactic longitude, as noted by several observers (e.g. Davidsen at al.…”

Flares of Red Dwarf Stars and Solar Activity

“…The analysis of photoelectric patrol observations over several years has shown such seasonal variations in stellar activity (Cristaldi and Rodono, 1972;; however, there is uncertainty in the statistical significance of these variations (Oskanian and Terebizh, 1971;Chugainov, 1972b;Kunkel and Zarate, 1974). Only for BY Dra do the available observations of synchronous variations of the small brightness oscillation period of the star, its mean brightness and colour, and the emission spectrum intensity indicate a 8-9 yr period that is similar to the solar cycle (Chugainov, 1973; Gershberg and Shakhovskaya, 1974).…”

Theory and Observations of Negative Preflares in UV Cet Stars

“…614V. P.GRININ 1/A (mk)• -the maan DBVi -anplitudaa of SPP aeoording to[2,[6][7][8] In 1975 synchronous photoelectric observations of flare stars in the visual and near IR-regions were initiated in the Crimea and then continued in Tashkent. Up to the present more than one hundred flares of UV Cet, EV Lac and AD Leo have been observed |6-8|.…”