Abstract:
We present X-ray, broad-band optical and low-frequency radio observations of the bright type
IIP supernova SN 2004et. The Chandra X-ray Observatory observed the supernova at three
epochs, and the optical coverage spans a period of ∼470 d since explosion. The X-ray emission
softens with time, and we characterize the X-ray luminosity evolution as Lₓ ∝ t−ᴼ·⁴. We use
the observed X-ray luminosity to estimate a mass-loss rate for the progenitor star of ∼2 ×
10−⁶ M☉yr−¹ . The optical light curve shows a pronounced plateau lasting for about 110 d.
Temporal evolution of photospheric radius and colour temperature during the plateau phase
is determined by making blackbody fits. We estimate the ejected mass of ⁵⁶Ni to be 0.06 ±
0.03 M☉. Using the expressions of Litvinova & Nadёzhin we estimate an explosion energy of
(0.98 ± 0.25) × 10⁵¹ erg. We also present a single epoch radio observation of SN 2004et. We
compare this with the predictions of the model proposed by Chevalier, Fransson & Nymark.
These multiwavelength studies suggest a main-sequence progenitor mass of ∼20 M☉ for
SN 2004et.
