Type IIb supernovae are likely massive stars which have lost most, but not all, of their hydrogen envelopes through tidal force by a companion star.

All but a small fraction of the hydrogen envelope was driven away from the star, leaving behind a white dwarf remnant composed primarily of the inert core.

When the hydrogen envelope has been further reduced to around 10 M, the envelope will have been so disrupted that it is believed further significant mass loss is not possible.

These stars will still have a hydrogen envelope and will explode as a type II supernova.

If the star is not surrounded by a thick, diffuse hydrogen envelope, the jets' material can pummel all the way to the stellar surface.

Type Ib and Ic supernovae lack hydrogen absorption lines, consistent with the theoretical prediction of stars that have lost their hydrogen envelope.

The brothers subsequently experimented with an elongated elliptical shape for the hydrogen envelope in a balloon they attempted to power and steer by means of oars and umbrellas.

When core collapse occurs during a supergiant phase when the star still has a hydrogen envelope, the result is a type II supernova.

At low metallicity, all stars will reach core collapse with a hydrogen envelope but sufficiently massive stars collapse directly to a black hole without producing a visible supernova.

BHB stars are more evolved and have helium burning cores, although they still have an extensive hydrogen envelope.