Browsing by Author "Leibundgut, Bruno"

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    Late-time HST photometry of SN1994I
    (2008) Clocchiatti, Alejandro; Wheeler, J. Craig; Kirshner, Robert P.; Branch, David; Challis, Peter; Chevalier, Roger A.; Filippenko, Alexei V.; Fransson, Claes; Garnavich, Peter; Leibundgut, Bruno; Panagia, Nino; Phillips, Mark M.; Suntzeff, Nicholas B.; Hoeflich, Peter A.; Gallardo, Jose
    We present multicolor Hubble Space Telescope ( HST) WFPC2 broadband observations of the Type Ic SN 1994I obtained similar to 280 d after maximum light. We measure the brightness of the SN and, relying on the detailed spectroscopic database of SN 1994I, we transform the ground-based photometry obtained at early times to the HST photometric system, deriving light curves for the WFPC2 F439W, F555W, F675W, and F814W passbands that extend from 7 days before to 280 days after maximum. We use the multicolor photometry to build a quasi-bolometric light curve of SN 1994I, and compare it with similarly constructed light curves of other supernovae. In doing so, we propose and test a scaling in energy and time that allows for a more meaningful comparison of the exponential tails of different events. Through comparison with models, we find that the late-time light curve of SN 1994I is consistent with that of spherically symmetric ejecta in homologous expansion, for which the ability to trap the gamma-rays produced by the radioactive decay of Co-56 diminishes roughly as the inverse of time squared. We also find that by the time of the HST photometry, the light curve was significantly energized by the annihilation of positrons.