supernova progenitors

myphot I lead a group searching for the stellar progenitors of nearby core-collapse supernovae in archive images from the Hubble Space Telescope, and large ground-based telescopes. Nearby supernovae are rare (about 13 discovered every year within about 30Mpc), but many of the host galaxies have been observed by Hubble. The most massive and luminous stars are visible, and we have confidently identified the progenitors of SN2003gd, SN2005cs, SN2008ax and SN2008bk, amongst others. Our latest results are presented in Smartt et al. MNRAS 2009, "The death of massive stars I. Observational constraints on the progenitors of type II-P supernovae".  The detection of the progenitor of the type IIb SN2008ax is in Crockett et al., MNRAS, 2008. My annual review article is available here :  S.J. Smartt ARAA, 2009, 47, 63  "Progenitors of core collapse SNe"    We have now expanded this project into the ESO NTT Large Programme "Supernovae variety and nucleosynthesis" with a broad range of european collaborators. We identify the supernovae with potential imaging from before explosion and use our VLT time to attempt to identify the progenitor stars. The NTT programme provides detailed monitoring, analysis and nucleosynthesis estimates (e.g. mass of Ni-56 ejected from the explosion).  The first paper from this new collaboration is on the detection of the progenitor of SN2009kr by Morgan Fraser et al. (ApJL, 2010).


pan-starrs

myphot We are members of the Pan-STARRS 1 Science Consortium and are leading Key Project 7 "Massive stars and supernovae progenitors". The aim of this project is to study the supernovae that arise from massive progenitors and understand the physical mechanisms behind the explosions.  See our pages on Transient Searches.


explosions of the most massive stars

myphot Recent discoveries suggest that the most massive stars known (between 50-150 solar masses) may die in diverse explosions. The explosions may be gamma-ray bursts, ultra-bright type II SNe, and SNe with pre-explosion outbursts.  The most luminous type Ic SN known (SN2007bi) may be a pair-instability explosion, or the core-collapse of a massive carbon-oxygen core from a star originally 50-100 solar masses. We study the SNe and the exotic explosions that may have come from the most massive stars. See Valenti et al. 2009 Nature; Pastorello et al. 2007 Nature ;  Young et al. A&A ,  2010. More recently we have shown that one of the new class of "ultra-bright" type I supernovae (SN2010gx) cannot be powered by nickel-56 decay, but must have some other mechanism that provides the enormous luminosity (absolute magnitudes up to M_B = -22). We also showed that SN2010gx turns into a type Ic at around 30 days after maximum, suggesting a Wolf-Rayet type progenitor star. See Pastorello, Smartt et al. 2010 ApJL.

the flames survey of massive stars

I was PI of successful ESO Large Programme, now completed :
"The VLT-FLAMES Survey of Massive Stars was an ESO Large Programme to understand rotational mixing and stellar mass loss in different metallicity environments, in order to better constrain massive star evolution. We gathered high-quality spectra of over 800 stars in the Galaxy and in the Magellanic Clouds. A sample of this size is unprecedented, enabled by the first high-resolution, wide-field, multi-object spectrograph on an 8-m telescope. We developed spectral analysis techniques that, in combination with non-LTE, line-blanketed model atmospheres, were used to quantitatively characterise every star. The large sample, combined with the theoretical developments, has produced exciting new insights into the evolution of the most massive stars." : C.J. Evans et al., 2008, ESO Messenger March 2008, Vol. 131, p25)
The spectral data archive, papers, results, and details  are available here. 

Chris Evans (UK ATC) is now leading this consortium, with a new ESO Large Programme approved :  The VLT-FLAMES Tarantula Survey. Paul Dunstall and Philip Dufton from Queen's are analysing the B-type stars from this spectroscopic survey.