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Name:Ascension Camero-Arranz


Institution:NASA VP62/USRA


Country:USA




Title:The strange case of A 0535+262 and HD 245770: an  X-ray/optical overview




Abstract:A 0535+262/HD 245770 is an unpredictable Be/X-ray binary system. Normal X-ray outbursts should take place every orbital period (~111 days), when the compact object interacts with the Be circumstellar disk. However, A 0535+262 shows a peculiar transient behavior with very long periods of quiescence in which the source disappears. A 0535+262 may renew activity directly with a very large event and a series of small outbursts until the X-ray activity stops. Or this source may undergo two consecutive giant X-ray events followed by series of small outbursts of decreasing amplitude, before another giant outburst takes place.  In the present work, we will perform a historical tour of this Be/X-ray binary system, including new Optical/X-ray observations, using data from different X-ray missions and optical observatories. Some clues to the not well understood X-behavior of A0535+26 are unveiled with observations of the strong Optical/X-ray correlation observed. The overall picture appears to be a system going through periods when the donor star has minimal circumstellar disk and then a dramatic disk recovery leads to a flare of X-ray emission. Unfortunately, this does not explain the variety of observed behaviors for this system.








            

            
            

              

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