AAS 201st Meeting, January, 2003
Session 54. Compact X-Ray Sources
Poster, Tuesday, January 7, 2003, 9:20am-6:30pm, Exhibit Hall AB

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[54.17U] X-ray binary A0538-66 during the years 1897 through 1951

K.L. Brock (Bates Coll. and Maria Mitchell Obs.), G.C. Clayton (Louisiana State U. and Maria Mitchell Obs.), E.R. Wollman (Bates Coll.)

Eye estimates of the photographic magnitudes of the X-ray binary A0538-66 were done to an accuracy of ±0.5 magnitude on 91 plates from the Harvard College Observatory collection covering the period from 1897 to 1951. The archival data confirms the presence of the 16.651-day periodicity first discovered in X-ray observations and subsequently seen in the visible. Ten outbursts of about a magnitude or more were found in the archival data, all occurring within 3.3 days of ephemeris maxima of the 16.651-day cycle. However, the majority of the plates close to ephemeris maxima do not show significant brightening of the star, indicating that the on-off behavior seen in recent years also operated during the years of the archival data. We are investigating a possible correlation of the outbursts with the 420.8-day visible periodicity of the system recently discovered in the MACHO data. This project was supported by the NSF/REU grant AST-0097694 and the Nantucket Maria Mitchell Association.

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