TY - JOUR
T1 - Prediction of the supersoft X-ray phase, helium enrichment, and turnoff time in the 2000 outburst of the recurrent nova CI aquilae
AU - Hachisu, Izumi
AU - Kato, Mariko
N1 - Funding Information:
We are very grateful to the VSNET members who observed CI Aql and sent their valuable data to the VSNET. We also thank R. E. Mennickent for his comments on their photometry and the anonymous referee for many kind comments that helped us to improve the manuscript. This research has been supported in part by the Grant-in-Aid for Scientific Research (11640226) of the Japanese Ministry of Education, Science, Culture, and Sports.
PY - 2001/6/1
Y1 - 2001/6/1
N2 - Recurrent nova CI Aquilae is still bright 300 days after the optical maximum, showing the slowest evolution among recurrent novae. We predict the turnoff time of the CI Aq1 2000 outburst coming in 2001 August after a supersoft X-ray source (SSS) phase lasts 250 days. We also predict helium enrichment of ejecta, He/H ∼ 0.25 by number. Observational confirmations are urgently required. Based on the optically thick wind mass-loss theory of the thermonuclear runaway model, we have also estimated the white dwarf (WD) mass to be MWD = 1.2 ± 0.05 M⊙ by fitting our theoretical light curves with the 1917 and 2000 outbursts. The mass of the hydrogen-rich envelope on the WD is also estimated to be ΔM ∼ 6 × 10-6 M⊙ at the optical maximum, indicating an average mass accretion rate of Macc ∼ 0.7 × 10-7 M⊙ yr-1 during the quiescent phase between the 1917 and 2000 outbursts. Using these obtained values, we have consistently reproduced the light curve in quiescence as well as the two outburst phases. Thus, we predict the turnoff time to be in 2001 August for the 2000 outburst. We strongly recommend soft X-ray observations to detect the SSS until 2001 August because the massive wind phase already ended in 2000 December and was followed by an SSS phase that very likely will last until 2001 August.
AB - Recurrent nova CI Aquilae is still bright 300 days after the optical maximum, showing the slowest evolution among recurrent novae. We predict the turnoff time of the CI Aq1 2000 outburst coming in 2001 August after a supersoft X-ray source (SSS) phase lasts 250 days. We also predict helium enrichment of ejecta, He/H ∼ 0.25 by number. Observational confirmations are urgently required. Based on the optically thick wind mass-loss theory of the thermonuclear runaway model, we have also estimated the white dwarf (WD) mass to be MWD = 1.2 ± 0.05 M⊙ by fitting our theoretical light curves with the 1917 and 2000 outbursts. The mass of the hydrogen-rich envelope on the WD is also estimated to be ΔM ∼ 6 × 10-6 M⊙ at the optical maximum, indicating an average mass accretion rate of Macc ∼ 0.7 × 10-7 M⊙ yr-1 during the quiescent phase between the 1917 and 2000 outbursts. Using these obtained values, we have consistently reproduced the light curve in quiescence as well as the two outburst phases. Thus, we predict the turnoff time to be in 2001 August for the 2000 outburst. We strongly recommend soft X-ray observations to detect the SSS until 2001 August because the massive wind phase already ended in 2000 December and was followed by an SSS phase that very likely will last until 2001 August.
KW - Binaries: close
KW - Novae, cataclysmic variables
KW - Stars: individual (CI aquilae)
KW - Stars: winds, outflows
KW - X-rays: stars
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U2 - 10.1086/320693
DO - 10.1086/320693
M3 - Article
AN - SCOPUS:0035373550
SN - 0004-637X
VL - 553
SP - L161-L164
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2 PART 2
ER -