Gas giants are also called failed stars because they contain the same basic elements as a star. Jupiter and Saturn are the gas giants of the Solar System.
"Jupiter is called a failed star because it is made of the same elements (hydrogen and helium) as is the Sun, but it is not massive enough to have the internal pressure and temperature necessary to cause hydrogen to fuse to helium, the energy source that powers the sun and most other stars.
Failed stars are also referred to as brown dwarfs. Jupiter is not a failed star. Its mass is too small for it. Same for Saturn and Neptune.
These objects, known as brown dwarfs, have many of the elements of their more famous siblings but lack the mass needed to jumpstart nuclear fusion in their core. Because brown dwarfs never burn fusion at their core, scientists sometimes refer to them as "failed stars."
Saturn is less than half as massive as Jupiter is, so their combined mass would be less than 1.5J. This is no where near the mass needed to become a star.
Saturn's rings are disappearing, and we don't know how much longer they will be around. Astronomers have known since the 1980s that Saturn's icy innermost rings are steadily eroding onto its upper atmosphere.
So, Jupiter cannot and will not spontaneously become a star, but if a minimum of 13 extra Jupiter-mass objects happen to collide with it, there is a chance it will.
An ancient brown dwarf is the most massive and purest such "failed star" ever discovered, a new study suggests. Researchers studied an object called SDSS J0104+1535, which lies about 750 light-years from Earth in the Milky Way's "halo," a population of extremely old stars above the galaxy's familiar spiral disk.
O-type stars form only a tiny fraction of main-sequence stars and the vast majority of these are towards the lower end of the mass range. The most massive and hottest types O3 and O2 are extremely rare, were only defined in 1971 and 2002 respectively, and only a handful are known in total.
Jupiter by mass is about 73 percent hydrogen and 24 percent helium. It's for this reason that Jupiter is sometimes called a failed star. But it's still unlikely that, left to the Solar System's own devices, Jupiter would even become close to being a star.
Its surface will reach the orbit of Venus or even beyond. In the best case scenario Earth's atmosphere will be stripped away and its surface will be turned to a molten, hostile lava. In the worst case, the entire planet will be consumed and vaporized by our once-reliable star.
So will Pluto and Neptune ever collide? No! You can see this in the image below, which shows a view as seen from the side as the planets orbit around the Sun. Most planets only make small excursions in the vertical and radial directions, but Pluto is an exception.
The rarest type of star is the type O star. It is the largest of the main sequence stars. In the entire milky way galaxy there are estimated to only be 20,000 of these stars or one in 20,00,000. The surface temperature is between 30,000 and 50,000 kelvin.
In the 21st century, the Great Red Spot has been observed to be shrinking in size. At the start of 2004, its length was about half that of a century earlier, when it reached a size of 40,000 km (25,000 mi), about three times the diameter of Earth. At the present rate of reduction, it will become circular by 2040.
While Jupiter often protects Earth and the other inner planets by deflecting comets and asteroids, sometimes it sends objects on a collision course straight toward the inner planets.
In 2006 the International Astronomical Union (IAU) demoted the much-loved Pluto from its position as the ninth planet from the Sun to one of five “dwarf planets.” The IAU had likely not anticipated the widespread outrage that followed the change in the solar system's lineup.
SM0313 is remarkable for the complete absence of detectable iron lines, writes lead author Stefan Keller (Australian National University). The star shows only four elements beyond hydrogen and helium: lithium, carbon, magnesium, and calcium, all of which are relatively light, and barely present in the star.
Red stars are the coolest. Yellow stars are hotter than red stars. White stars are hotter than red and yellow. Blue stars are the hottest stars of all.
Almost every galaxy can be classified as a spiral, elliptical, or irregular galaxy. Only 1-in-10,000 galaxies fall into the rarest category of all: ring galaxies.
But even on average, if we were to consider all 200-400 billion stars in our galaxy, a mean distance of perhaps 40,000 light years away, there are perhaps only a few hundred thousand that are already dead — one in a million — and they're heavily skewed towards being on the far side of the galaxy from where we are.
N6946-BH1 is a disappearing giant star formerly seen in the galaxy NGC 6946, on the northern border of the constellation of Cygnus. The star, either a red supergiant or a yellow hypergiant, was 25 times the mass of the sun, and was 20 million light years distant from Earth.
Very precise measurements show that the hot, bright star Achernar is the flattest known.
Thermonuclear ignition
If a gas giant has a layer with a large concentration of deuterium (>0.3%), ultra-high-speed (2×107 m/s) collision of a sufficiently large asteroid (diameter > 100 m) could ignite a thermonuclear reaction.
Take a laser that for about 20 billionths of a second can generate 500 trillion watts—the equivalent of five million million 100-watt light bulbs. Use all that laser power to create x rays that blow off the surface of the capsule. Wait 10 billionths of a second. Result: one miniature star.
It depends on what gas giant you're looking at and how you distinguish a “planet” from a “failed star.” A gas giant found in orbit around a star might be considered a planet like Jupiter around the Sun. An isolated gas giant is probably a failed star.