Is Jupiter an ineffective star? What would occur if it actually became one? Numerous astronomy papers, especially on the Internet, continue to assert that Jupiter should be considered a “failed star,” or a celestial entity whose mass “nearly” permitted it to ignite nuclear fusion reactions, but failed to do so. What is the validity of this claim?
This concept likely originated in the late 1970s, when it was determined that Jupiter emits into space around 1.5 times the amount of heat it gets from the Sun. This may have led to the conclusion that the planet once generated heat through nuclear fusion, which would have been partially conserved by thermal inertia. However, if this were the case, how is it that Saturn, which has a mass more than three times less than Jupiter, emits as much as 1.5 times the heat it gets from the Sun?
In fact, it is impossible for a celestial body of a given mass to emit more heat than one with a greater mass. In actuality, another reason explains the phenomenon. Below Jupiter’s gaseous atmosphere is a layer of liquid hydrogen and helium, followed by a layer of metallic hydrogen, and a solid core whose composition is still unknown. Helium, being heavier than hydrogen, tends to fall in the first layer, pushing up hydrogen.
This causes the release of gravitational energy and hence heat. In the case of Saturn, which is further from the Sun and hence colder, the “stirring” caused by thermal movements is less, and helium falls more easily. Consequently, the globe emits heat at a greater intensity.
Jupiter is an extremely average planet
“Failed stars” are an entirely different matter. But are we truly certain? Is the distance between a giant gas planet and the tiniest known star truly so vast and insurmountable? Although there is a minimum boundary, below which we speak of a planet, and a maximum threshold, above which we speak of a star, these boundaries are still being defined and knowing the true nature of a celestial object is not easy.
However, the smallest known star in our galaxy is a Red Dwarf named EBLM J0555-57Ab that is part of a triple system situated approximately 630 light-years from Earth in the constellation Pictor. Due to its small mass (less than half the mass of the sun), such a star cannot develop significant pressures within, and consequently, its nuclear processes create only a limited quantity of energy.
Because of the extreme minuteness of their combustion, these stars have exceptionally lengthy lives, hundreds of billions of years have been estimated for the tiniest. Given that the universe is approximately 13 billion years old, this indicates that no red dwarf has died out to date. Since the surface area of these stars is so small, the radiation losses of the remaining energy are incredibly slow.
As a result, even after all the hydrogen has been used, a red dwarf will continue to produce dimmer and dimmer light, until becoming an ice, invisible black dwarf. According to current models of stellar evolution, EBLM is a little star with barely enough mass to initiate hydrogen fusion in its core. Its diameter is 120,000 kilometers, which is less than one-tenth that of the Sun and even less than Jupiter’s equatorial diameter of 143,000 kilometers.
Yet it emits light and glows. You instantly question why Jupiter, which is even larger, has remained a planet and not transformed into a star. The brief response is: Jupiter is larger, but it lacks the mass to sustain nuclear fusion and the conversion of hydrogen to helium. In order for this to occur, an object must be sufficiently big and hot for individual atoms to overcome repulsive forces and compact. And if this tiny Red Dwarf succeeds in igniting its nuclear furnace, it is because despite its diminutive size, it has a mass that is around 85 times that of Jupiter, just the minimal value for a gas-filled sphere to compress its core to the point where it ignites nuclear fusion”.
188 grams per cubic centimeter, which is an outstanding value for density, is the reason for its success. Do you wish to know why this figure is referred to as “incredible”? It suffices to consider that Earth’s density, which is also the highest in the solar system, is only 5,5 grams per cubic centimeter, whereas Jupiter’s density is actually quite low. Only 1,3 grams per cubic centimeter. All of this indicates that Jupiter could only become a star if its mass suddenly grew 85 times higher than its current mass.
Exists any possibility that this could occur?
In the real world, of course not, but in the science-fiction universe created by the great Arthur Clarke, as we shall discover in a moment, it actually occurred. However, there is a somewhat more realistic path for Jupiter to become a star, and that is to attempt to become a Brown Dwarf. Specifically, a substellar object whose mass is insufficient to ignite the nuclear burning of hydrogen but sufficient to trigger the nuclear burning of deuterium, a lighter isotope of hydrogen.
Astronomers think that a brown dwarf normally has a mass between 13 to 80 times that of Jupiter, however the exact limits are still somewhat debatable. Brown dwarfs may resemble planets, but they form as stars, collapsing straight from a nebula of molecular hydrogen rather than through the accretion of material in the disk surrounding a star. The minimal mass threshold for a brown dwarf is consequently 13 Jovian masses, at which point deuterium burning commences.
In contrast, lithium fusion also occurs beyond sixty-five Jovian masses. Deuterium and lithium are found in minute quantities within a brown dwarf, therefore energy generation is severely limited in time and these celestial bodies are doomed to a long, progressive cooling. We are aware of brown dwarfs with surface temperatures of approximately 2,000 °C and others, evidently older, with surface temperatures of only 200 °C.
If Jupiter wants to become a brown dwarf, it would need to increase its mass by “just” thirteen times. And, albeit to a very minor degree, it would begin to generate light and heat, gradually warming the local planetary environment.
Could it be achieved?
The response is NO! Indeed, where might we locate twelve other planets as large as Jupiter? However, as was just noted, Arthur Clarke has left us something to write about. Do you recall these phrases? “ALL OF THESE WORLDS, EXCEPT EUROPE, ARE YOURS. ATTEMPT NO LANDING THERE. Use them jointly. Use them without fear.”
Jupiter evolves into a star in the novel 2010: Odyssey Two (on which the film 2010: The Year We Make Contact was subsequently based), but with the assistance of billions of alien monoliths that enhance the planet’s density above the critical level. In this manner, the hitherto gaseous planet begins to emit energy, and it is because to this technological marvel that Jupiter’s four satellites become suddenly suitable for human occupation.
Obviously, this is science fiction, not least because increasing Jupiter’s mass could have negative effects on the solar system. Envisioning that we have somehow managed to boost Jupiter’s mass by 85 times and initiating a nuclear chain reaction. In the meanwhile, it is important to note that, contrary to popular belief, doing so would not result in a disproportionate rise in size.
In reality, the diameter would rise by just 20 percent as a result of the compression of materials toward the center. Thus, we would obtain a red dwarf 170,000 km in diameter and 300 times less bright than the Sun. And since Jupiter is four times further from us than the Sun, we would receive only one-fifth as much energy on Earth as we do from the Sun. Essentially, there would be no difference in temperature.
Instead, there would be obvious ramifications for the star’s brilliance, which would look 80 times brighter than the full Moon in the night sky. Thus, night would be eradicated for significant portions of the year. And this would have significant effects on the nighttime behaviors of higher animals, as they would no longer be able to hunt or conceal effectively.
Phytoplankton would suddenly be capable of unrestricted growth, altering the equilibrium of the marine ecology. Stars would only be visible a handful of times each year, and astronomical observation from land would cease, as would the migration of certain birds at night. All of this, however, would pale in comparison to the cataclysmic gravitational changes that would come from Jupiter’s abrupt metamorphosis into a star.
Immediate danger would not come from changes in the orbits of the planets, which would not be felt for several centuries, but from the chaos that the immense mass of the red dwarf would bring to the delicate equilibrium of the Asteroid Belt. In actuality, the Asteroid Belt is currently guided and maintained together by Jupiter’s gravitational pull. If Jupiter’s mass were nearly multiplied by a hundred, the billions of objects that make up the Belt, which currently orbit the Sun like tranquil herds of bison, would be converted into a chaotic swarm of mad creatures.
Many would be attracted to the outer solar system and collide with the remaining gas giants, Saturn, Uranus, and Neptune, killing and spreading their moons. Others would be directed toward the inner solar system, bombarding the rocky planets, including Earth, and reducing them to formless, practically liquid masses. All the larger objects in the solar system would be destroyed by the blows of this cosmic billiards game gone berserk, and the remaining planets would either be expelled or diverted into orbits capable of orbiting the common barycenter of the two stars over time.
All of this would occur if Jupiter’s transformation from planet to star occurred instantly. If the solar system had already created a double star system, the situation would be different. In such theory, the formation of planets and the emergence of life would have followed distinct trajectories. Therefore, Jupiter is not a “failed star.” It was never destined to become a star, even if it was a little brown dwarf; it never even had a chance.
