[IAUC] CBET 1533: 20081009 : SUPERNOVA 2008fz

[IAUC mailing list]

                                                  Electronic Telegram No. 1533
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS en CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
CBAT en CFA.HARVARD.EDU (science)
URL http://www.cfa.harvard.edu/iau/cbat.html


SUPERNOVA 2008fz
     S. Benetti, A. Harutyunyan, and I. Agnoletto, Istituto Nazionale di
Astrofisica, Osservatorio Astronomico di Padova; S. Valenti and A. Pastorello,
Queen's University, Belfast; and V. Lorenzi, Telescopio Nazionale Galileo
(TNG), report that a spectrum of 2008fz (cf. CBET 1524), obtained on Oct. 9.16
UT with the 3.5-m TNG (+ DOLORES; range 350-930 nm, resolution 1.3 nm), is
dominated by a blue continuum, overimposed by Balmer lines in emission with
composite profiles.  The profiles consist of a broad component (FWHM about
3800 km/s) and a narrow (FWHM about 600 km/s) one.  In H_alpha, an even
broader component (about 8000 km/s) may be also visible.  The best fit to this
spectrum found via GELATO (Harutyunyan et al. 2008, A.Ap. 488, 383) is with
that of the type-IIn supernovae 1990S (Asiago Supernova Archive) and 2005gj
(Prieto et al. 2007, http://lanl.arxiv.org/abs/0706.4088).  The redshift, as
derived from the narrow peaks of the Balmer lines, is about 0.133.  Adopting
this redshift and an R-band magnitude (synthesized from the spectrum) of about
16.8, leads to a derived absolute magnitude of about -22.1 for 2008fz
(classified as a type-Ic supernova on CBET 1524), one of the brightest ever
observed.  The spectral appearance and the very high luminosity suggest that
the supernova ejecta have impacted onto external dense clumps of material,
similar to the model suggested for SN 2006gy by Smith and McCray (2007, Ap.J.
671, 17) and by Agnoletto et al. (2008, Ap.J., in press; see also website URL
http://lanl.arxiv.org/abs/0810.0635).


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2008 CBAT
2008 October 9                   (CBET 1533)              Daniel W. E. Green