2001AJ....121..517F

A set of four test regions covering a total celestial area of 520 deg² at low galactic latitude is investigated on a set of 130 century-old astrographic plates. About 8% of the 2x10⁵ stars with apparent B magnitude 10-14 and with total proper-motion component larger than 0".02 yr^–1 show a significant flickering greater than 0.4 mag in B over a timescale shorter than 20 minutes. About 25% of these stellar flare candidates concern stars with B-V∼0.2 (spectral type A7). A procedure to select pre-main-sequence stellar candidates from the distance-limited sample of 16x10³ disk dwarfs with detected flickering in B magnitude ≥0.4 is presented in view of a mass loss of 10^–8 M_☉.yr^–1, derived from the analysis of the angular momentum distribution of stellar orbits. Follow-up UBV photoelectric photometry at the present epoch of 200 nearby stellar flares along the Vulpecula Rift shows an effect of reddening in B-V and of blueing in U-B for about 10% of the targets. The detection of optically thin or thick disks around the selected targets is suggested.

The success rate in detecting optical flares in nearby stars of ∼1.5 M_☉ with as much as 5x10^–6 M_☉ dumped onto the central star during the past 100 years, from deep astrographic plates coupled with 1 m-class telescope is estimated to 10% with a kinematical bias that can be dealt with.