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Science 8 April 2005:
Vol. 308. no. 5719, pp. 231 - 233
DOI: 10.1126/science.1108953
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Reports

The Real-Time Stellar Evolution of Sakurai's Object

Marcin Hajduk,1,2 Albert A. Zijlstra,1* Falk Herwig,3 Peter A. M. van Hoof,4,5 Florian Kerber,6 Stefan Kimeswenger,7 Don L. Pollacco,4 Aneurin Evans,8 José A. Lopéz,9 Myfanwy Bryce,10 Stewart P. S. Eyres,11 Mikako Matsuura1

After a hot white dwarf ceases its nuclear burning, its helium may briefly and explosively reignite. This causes the star to evolve back into a cool giant, whereupon it experiences renewed mass ejection before reheating. A reignition event of this kind was observed in 1996 in V4334 Sgr (Sakurai's object). Its temperature decrease was 100 times the predicted rate. To understand its unexpectedly fast evolution, we have developed a model in which convective mixing is strongly suppressed under the influence of flash burning. The model predicts equally rapid reheating of the star. Radio emission from freshly ionized matter now shows that this reheating has begun. Such events may be an important source of carbon and carbonaceous dust in the Galaxy.

1 School of Physics and Astronomy, University of Manchester, Post Office Box 88, Manchester M60 1QD, UK.
2 Centrum Astronomii UMK, ul. Gagarina 11, PL-87-100 Torun, Poland.
3 Theoretical Astrophysics Group T-6, Los Alamos National Laboratory, MS B227, Los Alamos, NM 87545, USA.
4 APS Division, Department of Physics and Astronomy, Queen's University Belfast, Belfast BT7 1NN, UK.
5 Royal Observatory of Belgium, Ringlaan 3, Brussels, Belgium.
6 Space Telescope European Coordinating Facility, European Southern Observatory (ESO), Karl-Schwarzschild-Strasse 2, 85748 Garching, Germany.
7 Institut für Astrophysik, Universität Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria.
8 Department of Physics, School of Chemistry and Physics, Keele University, Staffordshire ST5 5BG, UK.
9 Instituto de Astronomía, Universidad Nacional Autónoma de México, Apdo. Postal 877, 22800 Ensenada, BC, Mexico.
10 Jodrell Bank Observatory, School of Physics and Astronomy, University of Manchester, Macclesfield, Cheshire SK11 9DL, UK.
11 Centre for Astrophysics, University of Central Lancashire, Preston PRI 2HE, UK.

* To whom correspondence should be addressed. E-mail: a.zijlstra{at}manchester.ac.uk

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