The cat is defined as being in estrus, in heat or in season (i.e. likely to become pregnant if mated) if it shows behavioral characteristics that are typical of a female cat in heat and if it stands for the male cat and allows mating to occur (i.e. is receptive to mating).he feline estrus cycle, otherwise known as the female reproductive cycle or heat cycle of the female cat, is a repetitive cycle of seasonally and hormonally driven fluctuations in a female cat's fertility and sexual receptivity.
Type Ib/c and II-L, and possibly most Type IIn, supernovae are only thought to be produced from stars having near-solar metallicity levels that result in high mass loss from massive stars, hence they are less common in older, more-distant galaxies.
But only a select few stars become supernovae. Many stars cool in later life to end their days as white dwarfs and, later, black dwarfs. Star Fusion. But massive stars, many times larger than our own sun, may create a supernova when their core's fusion process runs out of fuel.hese blasts produce much of the material in the universeâincluding some elements, like iron, which make up our planet and even ourselves. Heavy elements are only produced in supernovae, so all of us carry the remnants of these distant explosions within our own bodies.