The enigma of the oldest 'nova': The central star and nebula of CK Vul
Por:
Hajduk M., Zijlstra A.A., Van Hoof P.A.M., Lopez J.A., Drew J.E., Evans A., Eyres S.P.S., Gesicki K., Greimel R., Kerber F., Kimeswenger S., Richer M.G.
Publicada:
1 ene 2007
Resumen:
CK Vul is classified as, amongst others, the slowest known nova, a hibernating nova or a very late thermal pulse object. Following its eruption in ad 1670, the star remained visible for 2 yr. A 15-arcsec nebula was discovered in the 1980s, but the star itself has not been detected since the eruption. We here present radio images which reveal a 0.1-arcsec radio source with a flux of 1.5 mJy at 5 GHz. Deep H? images show a bipolar nebula with a longest extension of 70 arcsec, with the previously known compact nebula at its waist. The emission-line ratios show that the gas is shock-ionized, at velocities >100 km s-1. Dust emission yields an envelope mass of ?5 × 10-2 M?. Echelle spectra indicate outflow velocities up to 360 km s-1. From a comparison of images obtained in 1991 and 2004 we find evidence for expansion of the nebula, consistent with an origin in the 1670 explosion; the measured expansion is centred on the radio source. No optical or infrared counterpart is found at the position of the radio source. The radio emission is interpreted as thermal free-free emission from gas with Te ? 104 K. The radio source may be due to a remnant circumbinary disc, similar to those seen in some binary post-AGB stars. We discuss possible classifications of this unique outburst, including that of a sub-Chandrasekhar mass supernova, a nova eruption on a cool, low-mass white dwarf or a thermal pulse induced by accretion from a circumbinary disc. © 2007 RAS.
Filiaciones:
Hajduk M.:
Centrum Astronomii UMK, ul. Gagarina 11, PL-87-100 Torun, Poland
Zijlstra A.A.:
University of Manchester, School of Physics and Astronomy, PO Box 88, Manchester M60 1QD, United Kingdom
Van Hoof P.A.M.:
Royal Observatory of Belgium, Ringlaan 3, Brussels, Belgium
Lopez J.A.:
Instituto de Astronomía, Universidad Nacional Autónoma de México, Apdo. Postal 877, 22800 Ensenada, BC, Mexico
Drew J.E.:
Imperial College of Science, Technology and Medicine, Blackett Laboratory, Prince Consort Road, London SW7 2BW, United Kingdom
Evans A.:
Department of Physics, School of Chemistry and Physics, Keele University, Staffordshire ST5 5BG, United Kingdom
Eyres S.P.S.:
Centre for Astrophysics, University of Central Lancashire, Preston PRI 2HE, United Kingdom
Gesicki K.:
Centrum Astronomii UMK, ul. Gagarina 11, PL-87-100 Torun, Poland
Greimel R.:
Isaac Newton Group of Telescopes, Apartado de corras 321, Tenerife, Spain
Kerber F.:
European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching, Germany
Kimeswenger S.:
Institut für Astro- und Teilchenphysik, Universität Insbruck, Technikerstr. 25, 6020 Innsbruck, Austria
Richer M.G.:
Instituto de Astronomía, Universidad Nacional Autónoma de México, Apdo. Postal 877, 22800 Ensenada, BC, Mexico
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