[vsnet-preprint 16] (fwd) CI Aql preprint by Hachisu and Kato

[Taichi Kato <tkato>]

Dear VSNETers,

    We wrote a short paper on the recurrent nova CI Aql,
which has been accepted for publication in ApJ Letters.
Our paper is greatly indebted to the VSNET archival data.
Many thanks to the observers of CI Aql.

The paper can be accessed through astro-ph/0104461 (from May 1, 2001).

Please enjoy it !


Title: Prediction of supersoft X-ray phase, helium enrichment, and
        turn-off time in recurrent nova CI Aquilae 2000 outburst


Authors: Izumi Hachisu (Univ. of Tokyo) and Mariko Kato (Keio Univ.)

Comments: 8 pages including 5 figures, 
          to appear in the Astrophysical Journal, Letters


                    ABSTRACT

Recurrent nova CI Aquilae is still bright 300 days 
after the optical maximum, showing the slowest evolution
among recurrent novae.  We predict the turn-off time of CI Aql 
2000 outburst coming in August 2001 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 WD mass to be 1.2 +- 0.05 Msun 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 
6 x 10^{-6} Msun at the optical maximum, indicating an average mass 
accretion rate of 0.7 x 10^{-7} Msun/yr 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 turn-off time to be in August 2001 for the 2000 
outburst.  We strongly recommend soft X-ray observations to detect SSS
until August 2001 because the massive wind phase have already ended 
in December 2000 followed by an SSS phase that very likely 
lasts until August 2001.


with best wishes,

Izumi Hachisu
---------------------------------------------------------
Department of Earth Science and Astronomy
College of Arts and Sciences, University of Tokyo
Komaba 3-8-1, Meguro-ku, Tokyo 153-8902, Japan
---------------------------------------------------------
TEL: +81-3-5454-6615  FAX: +81-3-3465-3925
e-mail: hachisu@chianti.c.u-tokyo.ac.jp
WWW: http://grape.c.u-tokyo.ac.jp/~hachisu/index.shtml
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