We are told to be mindful of what we consume, lest we turn into a doughnut, a french fry, or a hamburger. We usually do not transmogrify into the various foods that we like. We may gain a few pounds which, we argue, will keep us warmer in the winter months.
Objects in the universe, however, can change completely into other objects if they ‘consume’ too much material. Any planet, for example, will stop being a planet if it eats enough hydrogen to grow to a mass that is 0.08 times the mass of the Sun.
In this case, the planet (any planet) will become a star. If Jupiter were just 80 times more massive then there would be a second star in our sky.
Likewise if Earth were 1 million times more massive it would be a star too, and if you or I would eat hamburgers and doughnuts until we weighed 0.08 times the mass of the Sun, we would also turn into stars.
An object with such a high mass will not have a choice, an option A or option B. ANY object of a certain minimum mass, or higher, will be a star. There is a reason for this. The heavier an object gets, the harder it is to sustain all that weight.
At first it is not so hard. When an object is reasonably small it will grow in size as it eats (as with humans). By the time an object is the size of Jupiter, however, if you add any more material to it then it will start to shrink. This unusual behavior shows that such an object is already beginning to collapse under its own enormous weight.
By the time the magical number of 0.08 solar masses is reached, an object is so heavy, the density is so high, and the pressure and temperature are so high in the core of the object that it is advantageous for hydrogen to fuse into helium to make energy.
So for astronomical objects how much you weigh determines one’s entire identity and lifetime. Let’s all eat sensibly this holiday season!
