A part of the star's outer atmosphere becomes optically thick due to partial ionization of certain elements.

The plasma mass is optically thick, and there's not much information from inside blackbody sources.

From the observations, it is estimated that this star has two discrete optically thick envelopes of dust and molecules.

When this radiation reaches the optically thick part of the accretion disk at a radius of around 1-2 light days, the X-rays are converted into heat.

This method is only valid for optically thick clouds.

Polish doughnuts are low viscosity, optically thick, radiation pressure supported accretion discs cooled by advection.

An optically thick circumstellar environment can potentially produce much larger CP than the interstellar medium.

Martin suggested that LP light can become CP near a star by multiple scattering in an optically thick asymmetric circumstellar dust cloud.

At present, the system is being obscured by an optically thick cloud of dust.

This also supported the theory that the Venusian surface was extremely hot or the atmosphere optically thick.