Browsing by Author "Bendek, E."

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    Discovery of the Low-Redshift Optical Afterglow of Grb 011121 and Its Progenitor Supernova Sn 2001ke1
    (2003) Garnavich, P.M.; Stanek, K.Z.; Wyrzykowski, L.; Infante, L.; Bendek, E.; Bersier, D.; Holland, S.T.; Jha, S.; Matheson, T.; Kirshner, R.P.; Krisciunas, K.; Phillips, M.M.; Carlberg, R.G.
    We present the discovery and follow-up observations of the afterglow of the gamma-ray burst GRB 011121 and its associated supernova SN 2001ke. Images were obtained with the Optical Gravitational Lensing Experiment 1.3 m telescope in BVRI passbands, starting 10.3 hr after the burst. The temporal analysis of our early data indicates a steep decay, independent of wavelength, with F-nu proportional to t(-1.72+/-0.05). There is no evidence for a break in the light curve earlier than 2.5 days after the burst. The spectral energy distribution determined from the early broadband photometry is a power law with Fnu proportional to nu(-0.66+/-0.13) after correcting for a large reddening. Spectra obtained with the Magellan 6.5 m Baade telescope reveal narrow emission lines from the host galaxy that provide a redshift of z = 0.362 +/- 0.001 to the GRB. We also present late R - and J-band observations of the afterglow similar to7-17 days after the burst. The late-time photometry shows a large deviation from the initial decline, and our data combined with Hubble Space Telescope photometry provide strong evidence for a supernova peaking about 12 rest-frame days after the GRB. The first spectrum ever obtained of a GRB supernova at cosmological distance revealed a blue continuum. SN 2001ke was more blue near maximum than SN 1998bw and faded more quickly, which demonstrates that a range of properties are possible in supernovae that generate GRBs. The blue color is consistent with a supernova interacting with circumstellar gas, and this progenitor wind is also evident in the optical afterglow. This is the best evidence to date that classical, long GRBs are generated by core-collapse supernovae.
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    Uncertainty of residual stresses measurement by layer removal
    (PERGAMON-ELSEVIER SCIENCE LTD, 2006) Bendek, E.; Lira, I.; Francois, M.; Vial, C.
    A model to evaluate the uncertainty in the measurement of the through-thickness residual stress distribution in plates by the layer removal technique is presented. Thin layers were chemically etched from a stripe on rectangular specimens cut from a low carbon cold-rolled steel sheet. Phase shifting laser interferometry was used to measure the ensuing curvature. Polynomials were least-squares adjusted to the curvatures as a function of the etched depth. The polynomials were inserted into an integro-differential equation relating the curvature to the residual stresses, which were assumed to be a function of depth only. A comparison with X-ray diffraction measurement of the surface residual stresses showed good agreement. The uncertainty was found to increase steeply at the surfaces and to depend mainly on the assumed value for the modulus of elasticity, on the curvature fit, and on the depth of etching. (C) 2006 Elsevier Ltd. All rights reserved.