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No progenitor detected in HST data for SN 2011hp

ATel #3771; M. Fraser, J. R. Maund, S. J. Smartt (Queens University Belfast), F. Bufano, S. Benetti (INAF Osservatorio Astronomico di Padova), N. Elias-Rosa (Institut de Ciencies de l'Espai)
on 17 Nov 2011; 20:54 UT
Credential Certification: Morgan Fraser (mfraser02@qub.ac.uk)

Subjects: Optical, Supernovae

We observed the Type Ic SN 2011hp (Monard, CBET 2899) with EFOSC2 on the New Technology Telescope at La Silla on 2011 Nov 17. Short exposures were taken to avoid saturating bright sources in the field; the combined image had a total exposure time of 660s in V band, with 1.8" seeing. The site of SN 2011hp was observed prior to explosion in the F606W filter with WFPC2 on board the Hubble Space Telescope, on 1996 Mar 16. A pipeline-drizzled mosaic of all four WFPC2 chip images was downloaded from the Hubble Legacy Archive, and used to attempt to identify a progenitor for the SN.

We identified 24 sources common to both images, and used their measured pixel coordinates to derive a geometric transformation between the two images with IRAF GEOMAP. The rms error in the transformation was 78 mas (corresponding to 0.8 WF pixels). Using this, the position of the SN was measured in the post-explosion image, and transformed to the pre-explosion image. We find the position of the SN to be (1349.15,1276.63) in hst_06359_16_wfpc2_f606w_wf_drz.fits. No progenitor candidate was identified as coincident with the SN in the pre-explosion image. A image of the site of the progenitor can be found at http://star.pst.qub.ac.uk/~sne/sn2011hp.png

We also performed PSF-fitting photometry with HSTPhot (Dolphin, 2000), but detected no source coincident with the SN at significance of 3 sigma or higher. A 5 sigma limiting magnitude of F606W > 26 (in the HST flight system) was determined from the non-detection of the progenitor. At a distance of 24.45 Mpc (from the recessional velocity of NGC 4219, via the HyperLEDA database), and for a foreground extinction of A_F606W = 0.61 (from NED), we set an absolute limiting magnitude for the progenitor of SN 2011hp of F606W < -6.6.

Type Ic SNe progenitors are thought to have lost their H and He rich envelopes either through wind-driven mass loss or through stripping in a binary system. In the former case, their progenitors would be Wolf-Rayet stars. For a typical Wolf-Rayet star bolometric correction of ~-4.5, the luminosity of the progenitor of SN 2011hp could be as high as log(L/Lsun) = 6.3 dex. For stripping in a binary system, a large range of lower mass progenitors would not be detected in the archival data.

The NTT observations were obtained as part of the ESO Large Programme "Supernova Variety and Nucleosynthesis Yields".