Effective Observation Time Research Articles

Flares of Orion population variables in the association Taurus T3

Thirteen new flare stars that are irregular variables of the Orion population have been found in an investigation of the Taurus Dark Cloud region by the homogeneous photographic multiexposure method using wide-angle Schmidt telescopes of the Byurakan Astrophysical Observatory. About 750 h of effective observation time led to the discovery of 17 flares in these stars. Analysis of the complicated light curves of the flares of these stars indicates a variety and multiplicity of phenomena and different dynamics of the energy release processes during the flares. The existence of flare stars that simultaneously exhibit the properties of T Tau and UV Cet type indicates that there is an intimate relationship between these types of young nonstationary stars. The flare star population in the region of the Taurus Dark Cloud is in all probability as young as the analogous groups of stars in Orion and Monoceros.

Observation of an unexplained event from a magnetic monopole detector

A single event was recorded by our 0.18 m2 inductive magnetic monopole detector, in a total effective observation time of 8,242 hours. None of the monitoring channels that record vibration, radiofrequency interference, and so on, indicated any extraneous cause for this event. An astrophysical estimate of the maximum number flux of monopoles suggests that the chances of a monopole having caused the event are less than 1 in 103. Alternative explanations for the candidate are considered, but none of them seem likely.

New flare stars in the region of the association Mon I

During 55 hours of effective observation time using the 67/90/192-cm Schmidt telescope at the Asiago Astrophysical Observatory of the University of Padua 29 flare stars have been found in the region of the association Mon I; of these, 17 are apparently members of the cluster NGC 2264. The frequency of flares in NGC 2264 is almost the same as in the region of the Orion association at the initial period of its observations. According to preliminary estimates, the total number of flare stars in Mon I is of order 800-1000. Among the new flare stars, a slow flare was observed in one.