SN 1998A: explosion of a blue supergiant |
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| Authors: | A Pastorello E Baron D Branch L Zampieri M Turatto M Ramina S Benetti E Cappellaro M Salvo F Patat A Piemonte J Sollerman B Leibundgut G Altavilla |
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| Institution: | Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, D-85741 Garching bei München, Germany;INAF –Osservatorio Astronomico di Padova, Vicolo dell' Osservatorio 5, I-35122 Padova, Italy;Department of Physics and Astronomy, University of Oklahoma, 440 W. Brooke Street, Norman, OK 73019, USA;INAF –Osservatorio Astronomico di Napoli, Via Moiariello 16, I-80131 Napoli, Italy;Australian National University, Mt Stromlo Observatory, 2611 Weston ACT, Australia;European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748, Garching bei München, Germany;Stockholm Observatory, Alba Nova University Centre, Roslagstullsbacken 21, SE-106 91 Stockholm, Sweden;Department of Astronomy, University of Barcelona, Martíi Franqués 1, E-08028 Barcelona, Spain |
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| Abstract: | We present spectroscopic and photometric observations of the peculiar Type II supernova (SN) 1998A. The light curves and spectra closely resemble those of SN 1987A, suggesting that the SN 1998A progenitor exploded when it was a compact blue supergiant. However, the comparison with SN 1987A also highlights some important differences: SN 1998A is more luminous and the spectra show bluer continua and larger expansion velocities at all epochs. These observational properties indicate that the explosion of SN 1998A is more energetic than SN 1987A and more typical of Type II supernovae. Comparing the observational data with simulations, we deduce that the progenitor of SN 1998A was a massive star (～25 M⊙) with a small pre-supernova radius (?6 × 1012 cm) . The Ba ii lines, unusually strong in SN 1987A and some faint II-P events, are almost normal in the case of SN 1998A, indicating that the temperature plays a key role in determining their strength. |
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| Keywords: | supernovae: general supernovae: individual: SN 1998A supernovae: individual: SN 1987A supernovae: individual: SN 1909A supernovae: individual: SN 2000cb galaxies: individual: IC 2627 |
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