X-ray transients and flares from active stellar systems

  • Carol Ambruster
  • Kent S. Wood
2. Rotation and Activity in Main Sequence Stars
Part of the Lecture Notes in Physics book series (LNP, volume 193)


Many X-ray flares detected to date from active cool stars were initially discovered as fast (≲ 3 hour) transients1,2,3. A survey of the HEAO A-1 Sky Survey Experiment 0.5–20 keV data for fast transients confirms the tendency for a significant fraction of such events to be associated with active stellar systems. Eight months of the mission (which include one full scan of the sky) were searched, yielding 10 transients of which three are identified with flares on cool stars. Of the remaining sources4, all but ones5 are at least consistent in their X-ray properties with a stellar flare origin.

We discuss below the three fast transients which we have identified with active stellar systems. They are EV Lac, a dM4.5e flare star (d = 5 pc)6, HD 8357, an RS CVn type binary (d ∼ 70 pc)7, and EQ Vir (BD-7°3646), a dK5 flare star (d = 16 pc)8.


Light Curve Cool Star Flare Star Fast Transient Small Flare 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Springer-Verlag 1984

Authors and Affiliations

  • Carol Ambruster
    • 1
  • Kent S. Wood
    • 1
  1. 1.E.O Hulburt Center for Space ResearchNaval Research LaboratoryWashington, D.C.

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