Spectroscopic observations of red dwarfs. III. Observations of red stars in the solar neighborhood

This list is based on 20 stars in the solar neighborhood for which there are 52 spectra. Twelve of them are known as UV Ceti flare stars. The others behave like flare stars, but are not known to be such. Among the 20 there are many binary and triple flare stars. They all belong to the disk population of the Galaxy. Red dwarfs comprise one of the numerous populations of the system. Flare stars either continue to flare or have ceased flare activity. Three diagrams are given that show satisfactory agreement with the expected ones. A cluster analysis is carried out, which is in agreement with the original proposition and confirms the foregoing.     

Possible representation for discovery observations of stellar flares

It is shown that the chronology of flare star discoveries in the Pleiades cluster and the Orion association can be described satisfactorily by various distribution functions (gamma, binomial, decreasing exponential, and delta) for the mean frequencies of stellar flares. However, it has been found that this is due to the uncertainty in the observationally derived distribution function for the mean frequency of stellar flares. The most likely function is that derived by Ambartsumian, which has a physical basis.Translated fromAstrofizika, Vol. 38, No. 1, pp. 25–32, January–March, 1995.     

Subsystems of flare stars of different ages in Orion and the Pleiades

The two best-studied subsystems of flare stars, in Orion and the Pleiades, which are of considerably different ages, are compared. It is shown that the observed differences between them are consistent with the evolutionary status of flare stars that represent a stage in the evolution of red dwarfs. It is found that less luminous stars exhibit higher flare frequencies. For equally luminous stars, flare activity is lower in older stars.Translated from Astrofizika, Vol. 37, No. 1, pp. 59–72, January–February, 1994.     

Sizes of real Trapeziums

Byurakansk Astrophysical Observatory. Translated fromAstrofizika, Vol. 35, No. 1, pp. 27–31, July–August, 1991.     

Optical observations of flare stars in the galaxy

Observations of flare stars in the galaxy are considered. UV Ceti type stars in the solar vicinity and flare stars is star clusters and associations have almost the same properties. The differences between them are connected with the age. Flare stars are one of the richest populations in the galaxy. The evolutionary path for all flare stars is the same.Published in Astrofizika, Vol. 38, No. 4, pp. 501–507, October–December, 1995.     

The first Byurakan spectral sky survey. Investigations of stars of late M and C spectral classes

The results of investigations of new faint M and C type stars discovered on the plates of the First Byurakan Spectral Sky Survey are reported. Among 161 newly discovered stars, 98 are identified with unknown IRAS point sources. It is probable that the majority of new M stars are Mirids according to their distributions on the IRAS color—color diagram. For J stars, a correlation between EW(C₂ + CN) and EW(C₂(0,1)) is found.Published in Astrofizika, Vol. 38, No. 4, pp. 543–548, October–December, 1995.     

French-Armenian scientific cooperation on study of some HII-regions with cigale

The results of the scientific cooperation between astronomers of the Byurakan and Marseille observatories on the study of diffuse matter in the Galaxy are presented.H -emission is discovered in the direction of h and x Per. Fabry-Perot observations of three HII-regions, Sh2-152, 153, and 106, show the expansion of the diffuse matter relative to the exciting stars. In the Sh2-106 region a probable jet is found. It is shown that in star forming regions the diffuse matter takes part in expansion motions together with stars.Published in Astrofizika, Vol. 38, No. 4, pp. 559–564, October–December, 1995.     

Investigation of late-type stars in the FBS survey. I. M stars

The spectral subtypes and luminosity classes are given for 15 comparatively faint M stars found on plates of the First Byurakan Spectroscopic Survey. Two of them are classified as M dwarfs. Most of the new M stars are probably Mirids.Translated from Astrofizika, Vol. 37, No. 1, pp. 73–82, January–February, 1994.     

Diffusional mechanism of emission from a charged particle in dust particles

The emission from a charged particle moving in a medium containing randomly distributed dust particles is considered. It is shown that in certain cases, the diffusional mechanism of emission is the principal one in the x-ray range. Possible astrophysical applications of this mechanism are considered. Spectral indices in the x-ray range are calculated, in particular. The calculated spectral indices agree well with those of active galactic nuclei. Translated from Astrofizika, Vol. 41, No. 3, pp. 443–457, July–September, 1998.