Flares of Red Dwarf Stars and Solar Activity

Abstract

Since that pioneer work a lot of new important observations of flare stars have been carried out. On the other hand, during the last 20-30 yr, mainly under the influence of solar researches, astrophysics has been enriched with new ideas and conceptions: the convective envelope theory, magnetohydrodynamics, plasma theory, and now many events of the solar activity have relatively complete physical interpretations. This stimulates an attempt to construct a flare star activity model that would be able to represent the total variety of up-to-date observations of these nonstationary objects.In this introductory report on flare stars, I should like firstly to compare stellar and solar flares, secondly to compare conditions in stellar and solar atmospheres where these violent events originate, and finally to consider some common problems of the solar and red dwarf flare activity. I intend to describe the up-to-date state of problems and to touch on their formation history to a small extent only.In starting a comparative examination of stellar and solar activities, I must remind you that at optical frequencies we receive from the Sun energy 10 14 times greater than that from the nearest flare stars. Therefore the investigations of the solar activity and Sherwood and Plaut (eds.), Variable Stars and Stellar Evolution, 47-64. All Rights Reserved.

Mechanisms for eclipsing in exotic eclipsing systems

“…According to one of these models, ε Aur is a massive F star . The later model is supported, in particular, by the similarity of the fundamental characteristics of ε Aur and the Kuwano object (PU Vul), which is a candidate post-AGB star [16]. observed in e Aur outside the eclipses [17].…”

PU Vul: 15 Years of Studies, Important Findings and Remaining Mysteries

“…A strong similarity between the spectrum of PU Vul and that of a normal F supergiant was observed in 1979-1983, during the prolonged brightness maxi- Year -1900 _ 176, ,781 |80, ,82, ,84, ,86, ,88, ,90, ,92, ,94 JD -2440000 mum. This similarity was noted from the energy distribution from UV to near IR (Nakagiri & Yamashita 1982, Friedjung et al 1984, Belyakina et al 1985, 1990, Vogel & Nussbaumer 1992 as well as from relative intensities of absorption lines (Hric et al 1980, Gershberg et al 1982, Yamashita et al 1982, 1983, Kolotilov 1983a, lijima & Ortolani 1984 and from quantitative analysis by the curve of growth method (Belyakina et al 1985, Kanamitsu 1991. During these years, PU Vul could not be distinguished from a normal F supergiant by its luminosity, effective temperature, physical parameters and chemical composition of its atmosphere.…”

“…During these years, PU Vul could not be distinguished from a normal F supergiant by its luminosity, effective temperature, physical parameters and chemical composition of its atmosphere. This fact leads us to consider the existence of a non-homogeneity of high luminosity F stars, and I consider the enigmatic e Aur a probable candidate for such a mimicry (Gershberg 1990). A general accordance between observable features of PU Vul and those of theoretical models for the explosion of an accreting white dwarf in a binary system was found, when observations were compared with Iben's (1982) computations ( Fig.…”

Flare Stars in Stellar Aggregates

“…terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0252921100069244 Some years ago it seemed that the optical flares could be explained with the nebular model proposed by Gershberg (1970) and Kunkel (1967).…”