Are there more than one sun




















What allows HD Ab to weather such chaos, Kratter said, is its location. The planet orbits about 80 astronomical units AU from its "main" parent star, and AU from the other two stars in the system, which are composed of a binary pair. One AU is the average distance from Earth to the sun — about 93 million miles, or million kilometers. Other known three-sun planets also lie far away from the binary stars in the system. But the planet is AU from the binary stars — about eight times the average distance between Pluto and the sun in our own solar system.

As long as the remaining stars in the system are far enough [away] not to disturb gravitationally the orbit of a planet in a significant way or disturb a protoplanetary disk earlier in the evolution , such planets will form and survive," said Maciej Konacki, a Polish astronomer who in reported a possible three-star planet called HD Ab. This world didn't show up in a follow-up study by another team in , leading some astronomers to conclude it probably doesn't exist.

These triple or multiple star systems might be one of the natural sources of free-floating planets. One key question to consider is how multisun planets get wedged into their orbits in the first place, researchers say. The answers are seldom straightforward, as the case of HD Ab shows. The planet is huge, at least four times the size of Jupiter.

It's unclear if there would be enough gas to form such a giant world out at 80 AU from the main star in the system. Also, radiation from the binary pair would have blown much of this material into space, making the accretion process even more difficult, researchers have said.

Another possibility is that the planet formed independently in the large molecular cloud that birthed the three stars, rather than from the disk of leftover material surrounding the main star. The final theory is that the planet formed very close to its parent star, along with a companion planet or two.

Over time, the planets' orbits would have tugged at each other, and eventually such interactions booted HD Ab out to its current location. And all stars are enormous and extremely bright compared to any planets circling them. That means that picking out a planet near a distant star is like spotting a firefly right next to a brilliant lighthouse miles away. Spotting an exoplanet around a faraway star is like spotting a firefly next to a lighthouse.

The light from the lighthouse is so bright that you would have a hard time spotting the flicker of a firefly. In the same way, all stars are bigger and staggeringly bright compared to the planets orbiting them. So far, the planets outside our solar system have proven to be fascinating and diverse. The force of gravity there would be much stronger than here at home. You would weigh twice as much there as you do on Earth!

Another planet, called Keplerb, turns out to orbit two stars. A sunset there would provide a view of two setting stars! The core extends from the sun's center to about a quarter of the way to its surface. Light from the core gets scattered in this zone, so that a single photon often may take a million years to pass through.

Roiling "convection cells" of gas dominate this zone. Two main kinds of solar convection cells exist — granulation cells about miles 1, kilometers wide and supergranulation cells about 20, miles 30, km in diameter.

The photosphere is the lowest layer of the sun's atmosphere, and emits the light we see. It is about miles km thick, although most of the light comes from its lowest third. Temperatures in the photosphere range from 11, F 6, C at the bottom to 7, F 4, C at the top. Next up is the chromosphere, which is hotter, up to 35, F 19, C , and is apparently made up entirely of spiky structures known as spicules typically some miles 1, km across and up to 6, miles 10, km high. After that is the transition region a few hundred to a few thousand miles thick, which is heated by the corona above it and sheds most of its light as ultraviolet rays.

At the top is the super-hot corona, which is made of structures such as loops and streams of ionized gas. The corona generally ranges from , F , C to Matter from the corona is blown off as the solar wind. The sun's magnetic field is typically only about twice as strong as Earth's magnetic field.

However, it becomes highly concentrated in small areas, reaching up to 3, times stronger than usual. These kinks and twists in the magnetic field develop because the sun spins more rapidly at the equator than at higher latitudes and because the inner parts of the sun rotate more quickly than the surface.

Related: Huge magnetic 'ropes' drive powerful sun explosions. These distortions create features ranging from sunspots to spectacular eruptions known as flares and coronal mass ejections. Flares are the most violent eruptions in the solar system, while coronal mass ejections are less violent but involve extraordinary amounts of matter — a single ejection can spout roughly 20 billion tons 18 billion metric tons of matter into space.

Just like most other stars, the sun is made up mostly of hydrogen, followed by helium. Nearly all the remaining matter consists of seven other elements — oxygen, carbon, neon, nitrogen, magnesium, iron and silicon. For every 1 million atoms of hydrogen in the sun, there are 98, of helium, of oxygen, of carbon, of neon, of nitrogen, 40 of magnesium, 35 of iron and 35 of silicon.

Related: What is the sun made of? Sunspots are relatively cool, dark features on the sun's surface that are often roughly circular. They emerge where dense bundles of magnetic field lines from the sun's interior break through the surface.



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