Searching for past outbursts of recurrent novae

Peter B. Robinson, Maria Mitchell Observatory
Geoffrey C. Clayton, Maria Mitchell Observatory
Bradley E. Schaefer, Louisiana State University


In the summer of 2004, a search for past outbursts of three known recurrent novae (RNe; V1017 Sgr, V3890 Sgr, and CI Aql) was conducted using digitized plates at the Maria Mitchell Observatory on Nantucket, Massachusetts. The plates cover the years 1913-1995. The search for past eruptions is the only way to obtain the real inter-eruption timescales for RNe, which is important for understanding whether RNe will ultimately collapse as Type la supernovae. No previously undiscovered eruptions were found. Nevertheless, the rich coverage of the plates significantly reduces the likelihood of these RNe having had an outburst in the years of our coverage. This is most critical in the case of CI Aql (a key system in upcoming tests on whether the white dwarf is gaining or losing mass), for which we show that no eruptions occurred from 1977 to 1995, despite a prediction of a nova event around 1980. Furthermore, V3890 Sgr was observed to have short-term variability during quiescence, with the B magnitude randomly varying between 15.4 and fainter than 16.7 (the plate limit), and thus our data might be useful for later period searches. In addition to the RN outburst search, we have also searched for second outbursts of four classical novae (CNe) that are RNe candidates. The idea is that these systems are suspected on various grounds of being RNe with only one discovered outburst, and this idea is being tested with our search for second eruptions. Our four CNe targets were V1016 Sgr, BS Sgr, V4444 Sgr, and V1172 Sgr. No second outbursts were found. © 2006. The Astronomical Society of the Pacific. All rights reserved.