Why is Jupiter not considered a star?

The smallest known star in our Milky Way galaxy is called EBLM J0555-57Ab, a star 600 light-years away, with an average radius of about 59,000 km, which is slightly larger than the star. Tho. It's also the star known to support hydrogen fusion in its core, the process that keeps stars glowing until they run out of fuel. In our Solar System, there are two objects larger than this small star, the Sun and Jupiter - like "a giant scoop of ice cream" with an average radius of 69,911km. But why is Jupiter considered only a planet and not a star?

The answer is simple and short: Jupiter does not have enough mass to fuse hydrogen into helium. EBLM J0555-57Ab has about 85 times the mass of Jupiter, about as light as a star, if it were lighter it wouldn't be able to burn hydrogen either. So can Jupiter "burn up" to become a star, if hypothesized that our solar system has other characteristics?

Jupiter and the Sun are more similar than we know

Gas giants may not be stars, but Jupiter is a rather complex entity. Its mass is 2.5 times the mass of all the other planets combined, a gas giant but with a really low density: about 1.33 grams per cubic centimeter, the density of gas on Earth. soil is 5.51 grams per cubic centimeter, four times higher than that of Jupiter.

However, Jupiter and the Sun have interesting similarities. The Sun's density is 1.41 grams per cubic centimeter, about the same as Jupiter's, and the two objects are very similar in composition. By mass, the Sun is about 71% hydrogen and 27% helium, with the remainder made up of small amounts of other elements. And Jupiter by mass is about 73 percent hydrogen and 24 percent helium. It is for this reason that Jupiter is sometimes referred to as a "fail star" but it is still unlikely that for Solar System instruments, Jupiter will become a star.

 Jupiter is a rather complex entity.

The reality is that stars and planets are born through completely different mechanisms. While stars are born when a dense node of matter in a molecular cloud amid the collapse of stars under its own gravity. As these stars rotate, it will pull more material from the cloud around it into a stellar accretion disk. As its mass and gravity increases, the star's core is squeezed even tighter, causing its temperature to increase. It eventually becomes so compressed and hot that it ignites the entire core and causes a fusion reaction.

According to the scientific understanding of star formation, once a star has completed accretion, the entire accretion disk is the remains that support the formation of planets. Astronomers think that, for "gas giants" like Jupiter, this process (known as cobblestone accretion) begins with small clumps of rock and dust in the disk. As they orbit a substar, these pieces of matter begin to collide, sticking together by electrostatic force. Eventually these growing clumps reach a large enough size - about 10 times the mass of the Earth, they will attract more and more gas from orbit around it thanks to great gravity.

Also from the time of its formation, Jupiter will gradually grow to its present mass, about 318 times the mass of Earth and equal to 1/1000 of the mass of the Sun. Once it has sucked up all the available material around it - which is quite small compared to the volume needed for hydrogen fusion, it stops growing. That's why Jupiter was never even close enough to be a star. Jupiter is similar in composition to the Sun not because it is a "failed star" but because it was born from the same molecular gas cloud that gave birth to the Sun.

Jupiter lies just above the giant mass limit.

Real failure stars

The vast universe has another class of objects known as "failed stars". These are brown dwarfs, and they fill the void between gas giants and other stars. These stars are about 13 times more massive than Jupiter, which is massive enough to support core fusion - not with ordinary hydrogen, but with deuterium. This element is also known as "heavy" hydrogen - an isotope of hydrogen with one proton and one neutron in the nucleus instead of just a single proton. Its fusion temperature and pressure are lower than the fusion temperature and pressure of hydrogen.

Reactions in the cores of these "failed stars" occur at lower masses, temperatures and pressures; deuterium fusion is an intermediate step on the path to hydrogen fusion for stars. , as they continue to accumulate mass. However, some objects never reach that mass, they are called brown dwarfs.

During the time after the existence of these stars was confirmed around 1995, we still did not know whether brown dwarfs were dormant stars or "ambitious" planets. However, some studies have demonstrated that they form and exist like stars, from the decay of molecular clouds rather than core accretion. And some brown dwarfs have even lower mass conditions for burning deuterium, indistinguishable from planets.

Jupiter lies just above the giant mass limit, which is lower than the mass of a star. It is the smallest mass that an object can form from these molecular clouds. So, if Jupiter was also formed in this way, it would also be considered a "failed star". However, data from NASA's Juno probe suggest that, at least for some time, Jupiter had a solid core - which is also consistent with the hypothesis from accretionary formation. core capacitor.

One modeling suggests that the upper limit of a planet's mass, formed through core accretion, is about 10 times the mass of Jupiter, equivalent only to the mass of Jupiter before the fusion reaction. deuterium compounds.

So, in all fairness, Jupiter should not be called a failure star, but a real star is not correct. Knowledge of how it formed will help us better understand how the universe works. In addition, Jupiter is a banded, stormy, swirling fireplace wonder in its own right, and without Jupiter, we humans might not be here.