 The star may contain more outer shells, but they were not detected by the VISIR instrument, as the field of view of the instrument is insufficient.Estimates of the outer shell are that it contains 0.17 solar masses of dust and was produced in an outburst 17,000 years ago that expelled 6-7 solar masses of gas.The properties of these shells are considered similar to those surrounding IRC+10420 (also an evolved massive star suffering heavy mass loss) as well as, for the outer shell, those around luminous blue variables, suggesting both that IRAS 17163−3907 is in a pre-LBV stage and that the ring nebulae that often surround those types of stars may originate with mass loss during the red supergiant stage.