Afterglow Light Curves from Jetted Gamma-ray Burst Ejecta in Stellar Winds

We revisit optical and radio afterglows arising from the shocks by relativistic conical ejecta running into pre-burst massive stellar winds. Under the homogeneous thin-shell approximation and the realistic treatment for lateral expansion of jets, our results show that a notable break of optical light curve within one decade in time indeed exists in most cases of our calculations by varying physical parameters within reasonable ranges. We rectify the conclusions of previous works on the jet+wind model, which claimed that there was no sharp break as the transition time lasts for two decades. Even for a relatively tenuous wind which cannot decelerate the relativistic jet to cause a sharp break within days, the wind termination shock due to the ram pressure balance by surrounding medium occurs at a small radius, i.e. several times 10 cm. The jet will pass through the wind environment within several hours and run into the outer uniform dense medium. The resulting optical light curve flattens with a shallower drop after the jet encounters the uniform medium, and finally declines deeply triggered by runaway lateral expansion.