What is the difference between a Type II-P supernova and a Type II-L supernova?

Type II supernovae are massive stars that have come to the end of their lives, which results in a spectacular explosion. They are categorized into two types- Type II-P and Type II-L supernova.

The main difference between the two is the light curve. A Type II-P supernova has a plateau in its light curve, which means that the brightness of the exploding star remains constant for a certain period of time before dropping off rapidly. The plateau is caused by the hydrogen gas in the outer layers of the star slowing down the shock wave that produces the supernova. On the other hand, a Type II-L supernova has a linear light curve, where the brightness drops off gradually over time.

Another important difference is the hydrogen envelope mass. Type II-P supernovae have a thicker hydrogen envelope, which causes the plateau in the light curve, while Type II-L supernovae have a thinner hydrogen envelope which leads to a very rapid decline in the light curve.

In conclusion, while both these supernova types belong to the same category, the difference in their light curve and the thickness of the hydrogen envelope makes one easily distinguishable from the other.