[IAUC] CBET 1227: 20080127 : SUPERNOVAE 2008M AND 2008O

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                                                  Electronic Telegram No. 1227
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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SUPERNOVAE 2008M AND 2008O
     G. Folatelli and F. Olivares, University of Chile; and N. Morrell, Las
Campanas Observatory, on the behalf of the Millennium Center for Supernova
Studies and Carnegie Supernova Project collaboration, report on spectrograms
(range 350-840 nm) of 2008M (cf. CBET 1214) and 2008O (cf. CBET 1220),
obtained on Jan. 27.2 UT with the European Southern Observatory 3.6-m
telescope (+ EFOSC2) at La Silla.
     SN 2008M is a type-II supernova, a few days after explosion.  Its
spectrum presents a blue continuum with P-Cyg features due to the Balmer
series lines.  In particular, the H-alpha line is dominated by the emission
component.  Cross-correlation with a library of supernova spectra using the
"Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J. 666,
1024) provides matches to SN 2005cs and SN 1999em at four days after
explosion.  Adopting the NED recession velocity of 2267 km/s for the host
galaxy (from Koribalski et al. 2004, A.J. 128, 16), the maximum absorption
of the H-beta line indicates an expansion velocity of about 8500 km/s.
     SN 2008O is a type-Ia supernova at about one week after maximum light.
The SNID code provides matches to SN 1994M and SN 1996X at seven and eight
days after maximum light, respectively.  Adopting the NED recession velocity
of 11649 km/s for the host galaxy (from Wegner et al. 2003, A.J. 126, 2268),
the maximum absorption of the Si II 635.5-nm line corresponds to an expansion
velocity of about 14500 km/s.  Such a velocity is remarkably high,
considering the age suggested by the spectral matches.  This is suggestive
(a) that SN 2008O may be a high-velocity type-Ia supernova like SN 1984A or
SN 2002bo, and (b) that the supernova may be closer to maximum light.


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                         (C) Copyright 2008 CBAT
2008 January 27                  (CBET 1227)              Daniel W. E. Green